| Message ID | 1489449360-14411-2-git-send-email-sstabellini@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, 13 Mar 2017 16:55:53 -0700 Stefano Stabellini <sstabellini@kernel.org> wrote: > Do not use the ring.h header installed on the system. Instead, import > the header into the QEMU codebase. This avoids problems when QEMU is > built against a Xen version too old to provide all the ring macros. > What kind of problems ? > Signed-off-by: Stefano Stabellini <stefano@aporeto.com> > CC: anthony.perard@citrix.com > CC: jgross@suse.com > --- > NB: The new macros have not been committed to Xen yet. Do not apply this > patch until they do. Why ? Does this break compat with older Xen ? > --- > --- > hw/block/xen_blkif.h | 2 +- > hw/usb/xen-usb.c | 2 +- > include/hw/xen/io/ring.h | 455 +++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 457 insertions(+), 2 deletions(-) > create mode 100644 include/hw/xen/io/ring.h > > diff --git a/hw/block/xen_blkif.h b/hw/block/xen_blkif.h > index 3300b6f..3e6e1ea 100644 > --- a/hw/block/xen_blkif.h > +++ b/hw/block/xen_blkif.h > @@ -1,7 +1,7 @@ > #ifndef XEN_BLKIF_H > #define XEN_BLKIF_H > > -#include <xen/io/ring.h> > +#include "hw/xen/io/ring.h" > #include <xen/io/blkif.h> > #include <xen/io/protocols.h> > > diff --git a/hw/usb/xen-usb.c b/hw/usb/xen-usb.c > index 8e676e6..370b3d9 100644 > --- a/hw/usb/xen-usb.c > +++ b/hw/usb/xen-usb.c > @@ -33,7 +33,7 @@ > #include "qapi/qmp/qint.h" > #include "qapi/qmp/qstring.h" > > -#include <xen/io/ring.h> > +#include "hw/xen/io/ring.h" > #include <xen/io/usbif.h> > > /* > diff --git a/include/hw/xen/io/ring.h b/include/hw/xen/io/ring.h > new file mode 100644 > index 0000000..cf01fc3 > --- /dev/null > +++ b/include/hw/xen/io/ring.h > @@ -0,0 +1,455 @@ > +/****************************************************************************** > + * ring.h > + * > + * Shared producer-consumer ring macros. > + * > + * Permission is hereby granted, free of charge, to any person obtaining a copy > + * of this software and associated documentation files (the "Software"), to > + * deal in the Software without restriction, including without limitation the > + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or > + * sell copies of the Software, and to permit persons to whom the Software is > + * furnished to do so, subject to the following conditions: > + * > + * The above copyright notice and this permission notice shall be included in > + * all copies or substantial portions of the Software. > + * > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE > + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER > + * DEALINGS IN THE SOFTWARE. > + * > + * Tim Deegan and Andrew Warfield November 2004. > + */ > + > +#ifndef __XEN_PUBLIC_IO_RING_H__ > +#define __XEN_PUBLIC_IO_RING_H__ > + > +#if __XEN_INTERFACE_VERSION__ < 0x00030208 > +#define xen_mb() mb() > +#define xen_rmb() rmb() > +#define xen_wmb() wmb() > +#endif > + > +typedef unsigned int RING_IDX; > + > +/* Round a 32-bit unsigned constant down to the nearest power of two. */ > +#define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1)) > +#define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x)) > +#define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x)) > +#define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x)) > +#define __RD32(_x) (((_x) & 0xffff0000) ? __RD16((_x)>>16)<<16 : __RD16(_x)) > + > +/* > + * Calculate size of a shared ring, given the total available space for the > + * ring and indexes (_sz), and the name tag of the request/response structure. > + * A ring contains as many entries as will fit, rounded down to the nearest > + * power of two (so we can mask with (size-1) to loop around). > + */ > +#define __CONST_RING_SIZE(_s, _sz) \ > + (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \ > + sizeof(((struct _s##_sring *)0)->ring[0]))) > +/* > + * The same for passing in an actual pointer instead of a name tag. > + */ > +#define __RING_SIZE(_s, _sz) \ > + (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0]))) > + > +/* > + * Macros to make the correct C datatypes for a new kind of ring. > + * > + * To make a new ring datatype, you need to have two message structures, > + * let's say request_t, and response_t already defined. > + * > + * In a header where you want the ring datatype declared, you then do: > + * > + * DEFINE_RING_TYPES(mytag, request_t, response_t); > + * > + * These expand out to give you a set of types, as you can see below. > + * The most important of these are: > + * > + * mytag_sring_t - The shared ring. > + * mytag_front_ring_t - The 'front' half of the ring. > + * mytag_back_ring_t - The 'back' half of the ring. > + * > + * To initialize a ring in your code you need to know the location and size > + * of the shared memory area (PAGE_SIZE, for instance). To initialise > + * the front half: > + * > + * mytag_front_ring_t front_ring; > + * SHARED_RING_INIT((mytag_sring_t *)shared_page); > + * FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); > + * > + * Initializing the back follows similarly (note that only the front > + * initializes the shared ring): > + * > + * mytag_back_ring_t back_ring; > + * BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); > + */ > + > +#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \ > + \ > +/* Shared ring entry */ \ > +union __name##_sring_entry { \ > + __req_t req; \ > + __rsp_t rsp; \ > +}; \ > + \ > +/* Shared ring page */ \ > +struct __name##_sring { \ > + RING_IDX req_prod, req_event; \ > + RING_IDX rsp_prod, rsp_event; \ > + union { \ > + struct { \ > + uint8_t smartpoll_active; \ > + } netif; \ > + struct { \ > + uint8_t msg; \ > + } tapif_user; \ > + uint8_t pvt_pad[4]; \ > + } pvt; \ > + uint8_t __pad[44]; \ > + union __name##_sring_entry ring[1]; /* variable-length */ \ > +}; \ > + \ > +/* "Front" end's private variables */ \ > +struct __name##_front_ring { \ > + RING_IDX req_prod_pvt; \ > + RING_IDX rsp_cons; \ > + unsigned int nr_ents; \ > + struct __name##_sring *sring; \ > +}; \ > + \ > +/* "Back" end's private variables */ \ > +struct __name##_back_ring { \ > + RING_IDX rsp_prod_pvt; \ > + RING_IDX req_cons; \ > + unsigned int nr_ents; \ > + struct __name##_sring *sring; \ > +}; \ > + \ > +/* Syntactic sugar */ \ > +typedef struct __name##_sring __name##_sring_t; \ > +typedef struct __name##_front_ring __name##_front_ring_t; \ > +typedef struct __name##_back_ring __name##_back_ring_t > + > +/* > + * Macros for manipulating rings. > + * > + * FRONT_RING_whatever works on the "front end" of a ring: here > + * requests are pushed on to the ring and responses taken off it. > + * > + * BACK_RING_whatever works on the "back end" of a ring: here > + * requests are taken off the ring and responses put on. > + * > + * N.B. these macros do NO INTERLOCKS OR FLOW CONTROL. > + * This is OK in 1-for-1 request-response situations where the > + * requestor (front end) never has more than RING_SIZE()-1 > + * outstanding requests. > + */ > + > +/* Initialising empty rings */ > +#define SHARED_RING_INIT(_s) do { \ > + (_s)->req_prod = (_s)->rsp_prod = 0; \ > + (_s)->req_event = (_s)->rsp_event = 1; \ > + (void)memset((_s)->pvt.pvt_pad, 0, sizeof((_s)->pvt.pvt_pad)); \ > + (void)memset((_s)->__pad, 0, sizeof((_s)->__pad)); \ > +} while(0) > + > +#define FRONT_RING_INIT(_r, _s, __size) do { \ > + (_r)->req_prod_pvt = 0; \ > + (_r)->rsp_cons = 0; \ > + (_r)->nr_ents = __RING_SIZE(_s, __size); \ > + (_r)->sring = (_s); \ > +} while (0) > + > +#define BACK_RING_INIT(_r, _s, __size) do { \ > + (_r)->rsp_prod_pvt = 0; \ > + (_r)->req_cons = 0; \ > + (_r)->nr_ents = __RING_SIZE(_s, __size); \ > + (_r)->sring = (_s); \ > +} while (0) > + > +/* How big is this ring? */ > +#define RING_SIZE(_r) \ > + ((_r)->nr_ents) > + > +/* Number of free requests (for use on front side only). */ > +#define RING_FREE_REQUESTS(_r) \ > + (RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons)) > + > +/* Test if there is an empty slot available on the front ring. > + * (This is only meaningful from the front. ) > + */ > +#define RING_FULL(_r) \ > + (RING_FREE_REQUESTS(_r) == 0) > + > +/* Test if there are outstanding messages to be processed on a ring. */ > +#define RING_HAS_UNCONSUMED_RESPONSES(_r) \ > + ((_r)->sring->rsp_prod - (_r)->rsp_cons) > + > +#ifdef __GNUC__ > +#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \ > + unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \ > + unsigned int rsp = RING_SIZE(_r) - \ > + ((_r)->req_cons - (_r)->rsp_prod_pvt); \ > + req < rsp ? req : rsp; \ > +}) > +#else > +/* Same as above, but without the nice GCC ({ ... }) syntax. */ > +#define RING_HAS_UNCONSUMED_REQUESTS(_r) \ > + ((((_r)->sring->req_prod - (_r)->req_cons) < \ > + (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ? \ > + ((_r)->sring->req_prod - (_r)->req_cons) : \ > + (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) > +#endif > + > +/* Direct access to individual ring elements, by index. */ > +#define RING_GET_REQUEST(_r, _idx) \ > + (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) > + > +/* > + * Get a local copy of a request. > + * > + * Use this in preference to RING_GET_REQUEST() so all processing is > + * done on a local copy that cannot be modified by the other end. > + * > + * Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this > + * to be ineffective where _req is a struct which consists of only bitfields. > + */ > +#define RING_COPY_REQUEST(_r, _idx, _req) do { \ > + /* Use volatile to force the copy into _req. */ \ > + *(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx); \ > +} while (0) > + > +#define RING_GET_RESPONSE(_r, _idx) \ > + (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp)) > + > +/* Loop termination condition: Would the specified index overflow the ring? */ > +#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \ > + (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r)) > + > +/* Ill-behaved frontend determination: Can there be this many requests? */ > +#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \ > + (((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r)) > + > +#define RING_PUSH_REQUESTS(_r) do { \ > + xen_wmb(); /* back sees requests /before/ updated producer index */ \ > + (_r)->sring->req_prod = (_r)->req_prod_pvt; \ > +} while (0) > + > +#define RING_PUSH_RESPONSES(_r) do { \ > + xen_wmb(); /* front sees resps /before/ updated producer index */ \ > + (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ > +} while (0) > + > +/* > + * Notification hold-off (req_event and rsp_event): > + * > + * When queueing requests or responses on a shared ring, it may not always be > + * necessary to notify the remote end. For example, if requests are in flight > + * in a backend, the front may be able to queue further requests without > + * notifying the back (if the back checks for new requests when it queues > + * responses). > + * > + * When enqueuing requests or responses: > + * > + * Use RING_PUSH_{REQUESTS,RESPONSES}_AND_CHECK_NOTIFY(). The second argument > + * is a boolean return value. True indicates that the receiver requires an > + * asynchronous notification. > + * > + * After dequeuing requests or responses (before sleeping the connection): > + * > + * Use RING_FINAL_CHECK_FOR_REQUESTS() or RING_FINAL_CHECK_FOR_RESPONSES(). > + * The second argument is a boolean return value. True indicates that there > + * are pending messages on the ring (i.e., the connection should not be put > + * to sleep). > + * > + * These macros will set the req_event/rsp_event field to trigger a > + * notification on the very next message that is enqueued. If you want to > + * create batches of work (i.e., only receive a notification after several > + * messages have been enqueued) then you will need to create a customised > + * version of the FINAL_CHECK macro in your own code, which sets the event > + * field appropriately. > + */ > + > +#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ > + RING_IDX __old = (_r)->sring->req_prod; \ > + RING_IDX __new = (_r)->req_prod_pvt; \ > + xen_wmb(); /* back sees requests /before/ updated producer index */ \ > + (_r)->sring->req_prod = __new; \ > + xen_mb(); /* back sees new requests /before/ we check req_event */ \ > + (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ > + (RING_IDX)(__new - __old)); \ > +} while (0) > + > +#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ > + RING_IDX __old = (_r)->sring->rsp_prod; \ > + RING_IDX __new = (_r)->rsp_prod_pvt; \ > + xen_wmb(); /* front sees resps /before/ updated producer index */ \ > + (_r)->sring->rsp_prod = __new; \ > + xen_mb(); /* front sees new resps /before/ we check rsp_event */ \ > + (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ > + (RING_IDX)(__new - __old)); \ > +} while (0) > + > +#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \ > + (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ > + if (_work_to_do) break; \ > + (_r)->sring->req_event = (_r)->req_cons + 1; \ > + xen_mb(); \ > + (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ > +} while (0) > + > +#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \ > + (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ > + if (_work_to_do) break; \ > + (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ > + xen_mb(); \ > + (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ > +} while (0) > + > + > +/* > + * DEFINE_XEN_FLEX_RING_AND_INTF defines two monodirectional rings and > + * functions to check if there is data on the ring, and to read and > + * write to them. > + * > + * DEFINE_XEN_FLEX_RING is similar to DEFINE_XEN_FLEX_RING_AND_INTF, but > + * does not define the indexes page. As different protocols can have > + * extensions to the basic format, this macro allow them to define their > + * own struct. > + * > + * XEN_FLEX_RING_SIZE > + * Convenience macro to calculate the size of one of the two rings > + * from the overall order. > + * > + * $NAME_mask > + * Function to apply the size mask to an index, to reduce the index > + * within the range [0-size]. > + * > + * $NAME_read_packet > + * Function to read data from the ring. The amount of data to read is > + * specified by the "size" argument. > + * > + * $NAME_write_packet > + * Function to write data to the ring. The amount of data to write is > + * specified by the "size" argument. > + * > + * $NAME_get_ring_ptr > + * Convenience function that returns a pointer to read/write to the > + * ring at the right location. > + * > + * $NAME_data_intf > + * Indexes page, shared between frontend and backend. It also > + * contains the array of grant refs. > + * > + * $NAME_queued > + * Function to calculate how many bytes are currently on the ring, > + * ready to be read. It can also be used to calculate how much free > + * space is currently on the ring (ring_size - $NAME_queued()). > + */ > +#define XEN_FLEX_RING_SIZE(order) \ > + (1UL << (order + PAGE_SHIFT - 1)) > + > +#define DEFINE_XEN_FLEX_RING_AND_INTF(name) \ > +struct name##_data_intf { \ > + RING_IDX in_cons, in_prod; \ > + \ > + uint8_t pad1[56]; \ > + \ > + RING_IDX out_cons, out_prod; \ > + \ > + uint8_t pad2[56]; \ > + \ > + RING_IDX ring_order; \ > + grant_ref_t ref[]; \ > +}; \ > +DEFINE_XEN_FLEX_RING(name); > + > +#define DEFINE_XEN_FLEX_RING(name) \ > +static inline RING_IDX name##_mask(RING_IDX idx, RING_IDX ring_size) \ > +{ \ > + return (idx & (ring_size - 1)); \ > +} \ > + \ > +static inline RING_IDX name##_mask_order(RING_IDX idx, RING_IDX ring_order) \ > +{ \ > + return (idx & (XEN_FLEX_RING_SIZE(ring_order) - 1)); \ > +} \ > + \ > +static inline unsigned char* name##_get_ring_ptr(unsigned char *buf, \ > + RING_IDX idx, \ > + RING_IDX ring_order) \ > +{ \ > + return buf + name##_mask_order(idx, ring_order); \ > +} \ > + \ > +static inline void name##_read_packet(const unsigned char *buf, \ > + RING_IDX masked_prod, RING_IDX *masked_cons, \ > + RING_IDX ring_size, void *opaque, size_t size) { \ > + if (*masked_cons < masked_prod || \ > + size <= ring_size - *masked_cons) { \ > + memcpy(opaque, buf + *masked_cons, size); \ > + } else { \ > + memcpy(opaque, buf + *masked_cons, ring_size - *masked_cons); \ > + memcpy((unsigned char *)opaque + ring_size - *masked_cons, buf, \ > + size - (ring_size - *masked_cons)); \ > + } \ > + *masked_cons = name##_mask(*masked_cons + size, ring_size); \ > +} \ > + \ > +static inline void name##_write_packet(unsigned char *buf, \ > + RING_IDX *masked_prod, RING_IDX masked_cons, \ > + RING_IDX ring_size, const void *opaque, size_t size) { \ > + if (*masked_prod < masked_cons || \ > + size <= ring_size - *masked_prod) { \ > + memcpy(buf + *masked_prod, opaque, size); \ > + } else { \ > + memcpy(buf + *masked_prod, opaque, ring_size - *masked_prod); \ > + memcpy(buf, (unsigned char *)opaque + (ring_size - *masked_prod), \ > + size - (ring_size - *masked_prod)); \ > + } \ > + *masked_prod = name##_mask(*masked_prod + size, ring_size); \ > +} \ > + \ > +struct name##_data { \ > + unsigned char *in; /* half of the allocation */ \ > + unsigned char *out; /* half of the allocation */ \ > +}; \ > + \ > + \ > +static inline RING_IDX name##_queued(RING_IDX prod, \ > + RING_IDX cons, RING_IDX ring_size) \ > +{ \ > + RING_IDX size; \ > + \ > + if (prod == cons) \ > + return 0; \ > + \ > + prod = name##_mask(prod, ring_size); \ > + cons = name##_mask(cons, ring_size); \ > + \ > + if (prod == cons) \ > + return ring_size; \ > + \ > + if (prod > cons) \ > + size = prod - cons; \ > + else \ > + size = ring_size - (cons - prod); \ > + return size; \ > +}; > + > +#endif /* __XEN_PUBLIC_IO_RING_H__ */ > + > +/* > + * Local variables: > + * mode: C > + * c-file-style: "BSD" > + * c-basic-offset: 4 > + * tab-width: 4 > + * indent-tabs-mode: nil > + * End: > + */
On Wed, 15 Mar 2017, Greg Kurz wrote: > On Mon, 13 Mar 2017 16:55:53 -0700 > Stefano Stabellini <sstabellini@kernel.org> wrote: > > > Do not use the ring.h header installed on the system. Instead, import > > the header into the QEMU codebase. This avoids problems when QEMU is > > built against a Xen version too old to provide all the ring macros. > > > > What kind of problems ? The FLEX macros are only available in Xen 4.9+ (still unreleased). However, aside from these macros, the Xen 9pfs frontends and backends could work fine on any Xen releases. In fact, the Xen public/io headers are only provided as reference. > > Signed-off-by: Stefano Stabellini <stefano@aporeto.com> > > CC: anthony.perard@citrix.com > > CC: jgross@suse.com > > --- > > NB: The new macros have not been committed to Xen yet. Do not apply this > > patch until they do. > > Why ? Does this break compat with older Xen ? No, it does not break compatibility. But I think it is a good idea to commit the header to QEMU only after the corresponding Xen header has been accepted. I don't want the two to diverge. > > --- > > --- > > hw/block/xen_blkif.h | 2 +- > > hw/usb/xen-usb.c | 2 +- > > include/hw/xen/io/ring.h | 455 +++++++++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 457 insertions(+), 2 deletions(-) > > create mode 100644 include/hw/xen/io/ring.h > > > > diff --git a/hw/block/xen_blkif.h b/hw/block/xen_blkif.h > > index 3300b6f..3e6e1ea 100644 > > --- a/hw/block/xen_blkif.h > > +++ b/hw/block/xen_blkif.h > > @@ -1,7 +1,7 @@ > > #ifndef XEN_BLKIF_H > > #define XEN_BLKIF_H > > > > -#include <xen/io/ring.h> > > +#include "hw/xen/io/ring.h" > > #include <xen/io/blkif.h> > > #include <xen/io/protocols.h> > > > > diff --git a/hw/usb/xen-usb.c b/hw/usb/xen-usb.c > > index 8e676e6..370b3d9 100644 > > --- a/hw/usb/xen-usb.c > > +++ b/hw/usb/xen-usb.c > > @@ -33,7 +33,7 @@ > > #include "qapi/qmp/qint.h" > > #include "qapi/qmp/qstring.h" > > > > -#include <xen/io/ring.h> > > +#include "hw/xen/io/ring.h" > > #include <xen/io/usbif.h> > > > > /* > > diff --git a/include/hw/xen/io/ring.h b/include/hw/xen/io/ring.h > > new file mode 100644 > > index 0000000..cf01fc3 > > --- /dev/null > > +++ b/include/hw/xen/io/ring.h > > @@ -0,0 +1,455 @@ > > +/****************************************************************************** > > + * ring.h > > + * > > + * Shared producer-consumer ring macros. > > + * > > + * Permission is hereby granted, free of charge, to any person obtaining a copy > > + * of this software and associated documentation files (the "Software"), to > > + * deal in the Software without restriction, including without limitation the > > + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or > > + * sell copies of the Software, and to permit persons to whom the Software is > > + * furnished to do so, subject to the following conditions: > > + * > > + * The above copyright notice and this permission notice shall be included in > > + * all copies or substantial portions of the Software. > > + * > > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR > > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, > > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE > > + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER > > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING > > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER > > + * DEALINGS IN THE SOFTWARE. > > + * > > + * Tim Deegan and Andrew Warfield November 2004. > > + */ > > + > > +#ifndef __XEN_PUBLIC_IO_RING_H__ > > +#define __XEN_PUBLIC_IO_RING_H__ > > + > > +#if __XEN_INTERFACE_VERSION__ < 0x00030208 > > +#define xen_mb() mb() > > +#define xen_rmb() rmb() > > +#define xen_wmb() wmb() > > +#endif > > + > > +typedef unsigned int RING_IDX; > > + > > +/* Round a 32-bit unsigned constant down to the nearest power of two. */ > > +#define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1)) > > +#define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x)) > > +#define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x)) > > +#define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x)) > > +#define __RD32(_x) (((_x) & 0xffff0000) ? __RD16((_x)>>16)<<16 : __RD16(_x)) > > + > > +/* > > + * Calculate size of a shared ring, given the total available space for the > > + * ring and indexes (_sz), and the name tag of the request/response structure. > > + * A ring contains as many entries as will fit, rounded down to the nearest > > + * power of two (so we can mask with (size-1) to loop around). > > + */ > > +#define __CONST_RING_SIZE(_s, _sz) \ > > + (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \ > > + sizeof(((struct _s##_sring *)0)->ring[0]))) > > +/* > > + * The same for passing in an actual pointer instead of a name tag. > > + */ > > +#define __RING_SIZE(_s, _sz) \ > > + (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0]))) > > + > > +/* > > + * Macros to make the correct C datatypes for a new kind of ring. > > + * > > + * To make a new ring datatype, you need to have two message structures, > > + * let's say request_t, and response_t already defined. > > + * > > + * In a header where you want the ring datatype declared, you then do: > > + * > > + * DEFINE_RING_TYPES(mytag, request_t, response_t); > > + * > > + * These expand out to give you a set of types, as you can see below. > > + * The most important of these are: > > + * > > + * mytag_sring_t - The shared ring. > > + * mytag_front_ring_t - The 'front' half of the ring. > > + * mytag_back_ring_t - The 'back' half of the ring. > > + * > > + * To initialize a ring in your code you need to know the location and size > > + * of the shared memory area (PAGE_SIZE, for instance). To initialise > > + * the front half: > > + * > > + * mytag_front_ring_t front_ring; > > + * SHARED_RING_INIT((mytag_sring_t *)shared_page); > > + * FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); > > + * > > + * Initializing the back follows similarly (note that only the front > > + * initializes the shared ring): > > + * > > + * mytag_back_ring_t back_ring; > > + * BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); > > + */ > > + > > +#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \ > > + \ > > +/* Shared ring entry */ \ > > +union __name##_sring_entry { \ > > + __req_t req; \ > > + __rsp_t rsp; \ > > +}; \ > > + \ > > +/* Shared ring page */ \ > > +struct __name##_sring { \ > > + RING_IDX req_prod, req_event; \ > > + RING_IDX rsp_prod, rsp_event; \ > > + union { \ > > + struct { \ > > + uint8_t smartpoll_active; \ > > + } netif; \ > > + struct { \ > > + uint8_t msg; \ > > + } tapif_user; \ > > + uint8_t pvt_pad[4]; \ > > + } pvt; \ > > + uint8_t __pad[44]; \ > > + union __name##_sring_entry ring[1]; /* variable-length */ \ > > +}; \ > > + \ > > +/* "Front" end's private variables */ \ > > +struct __name##_front_ring { \ > > + RING_IDX req_prod_pvt; \ > > + RING_IDX rsp_cons; \ > > + unsigned int nr_ents; \ > > + struct __name##_sring *sring; \ > > +}; \ > > + \ > > +/* "Back" end's private variables */ \ > > +struct __name##_back_ring { \ > > + RING_IDX rsp_prod_pvt; \ > > + RING_IDX req_cons; \ > > + unsigned int nr_ents; \ > > + struct __name##_sring *sring; \ > > +}; \ > > + \ > > +/* Syntactic sugar */ \ > > +typedef struct __name##_sring __name##_sring_t; \ > > +typedef struct __name##_front_ring __name##_front_ring_t; \ > > +typedef struct __name##_back_ring __name##_back_ring_t > > + > > +/* > > + * Macros for manipulating rings. > > + * > > + * FRONT_RING_whatever works on the "front end" of a ring: here > > + * requests are pushed on to the ring and responses taken off it. > > + * > > + * BACK_RING_whatever works on the "back end" of a ring: here > > + * requests are taken off the ring and responses put on. > > + * > > + * N.B. these macros do NO INTERLOCKS OR FLOW CONTROL. > > + * This is OK in 1-for-1 request-response situations where the > > + * requestor (front end) never has more than RING_SIZE()-1 > > + * outstanding requests. > > + */ > > + > > +/* Initialising empty rings */ > > +#define SHARED_RING_INIT(_s) do { \ > > + (_s)->req_prod = (_s)->rsp_prod = 0; \ > > + (_s)->req_event = (_s)->rsp_event = 1; \ > > + (void)memset((_s)->pvt.pvt_pad, 0, sizeof((_s)->pvt.pvt_pad)); \ > > + (void)memset((_s)->__pad, 0, sizeof((_s)->__pad)); \ > > +} while(0) > > + > > +#define FRONT_RING_INIT(_r, _s, __size) do { \ > > + (_r)->req_prod_pvt = 0; \ > > + (_r)->rsp_cons = 0; \ > > + (_r)->nr_ents = __RING_SIZE(_s, __size); \ > > + (_r)->sring = (_s); \ > > +} while (0) > > + > > +#define BACK_RING_INIT(_r, _s, __size) do { \ > > + (_r)->rsp_prod_pvt = 0; \ > > + (_r)->req_cons = 0; \ > > + (_r)->nr_ents = __RING_SIZE(_s, __size); \ > > + (_r)->sring = (_s); \ > > +} while (0) > > + > > +/* How big is this ring? */ > > +#define RING_SIZE(_r) \ > > + ((_r)->nr_ents) > > + > > +/* Number of free requests (for use on front side only). */ > > +#define RING_FREE_REQUESTS(_r) \ > > + (RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons)) > > + > > +/* Test if there is an empty slot available on the front ring. > > + * (This is only meaningful from the front. ) > > + */ > > +#define RING_FULL(_r) \ > > + (RING_FREE_REQUESTS(_r) == 0) > > + > > +/* Test if there are outstanding messages to be processed on a ring. */ > > +#define RING_HAS_UNCONSUMED_RESPONSES(_r) \ > > + ((_r)->sring->rsp_prod - (_r)->rsp_cons) > > + > > +#ifdef __GNUC__ > > +#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \ > > + unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \ > > + unsigned int rsp = RING_SIZE(_r) - \ > > + ((_r)->req_cons - (_r)->rsp_prod_pvt); \ > > + req < rsp ? req : rsp; \ > > +}) > > +#else > > +/* Same as above, but without the nice GCC ({ ... }) syntax. */ > > +#define RING_HAS_UNCONSUMED_REQUESTS(_r) \ > > + ((((_r)->sring->req_prod - (_r)->req_cons) < \ > > + (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ? \ > > + ((_r)->sring->req_prod - (_r)->req_cons) : \ > > + (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) > > +#endif > > + > > +/* Direct access to individual ring elements, by index. */ > > +#define RING_GET_REQUEST(_r, _idx) \ > > + (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) > > + > > +/* > > + * Get a local copy of a request. > > + * > > + * Use this in preference to RING_GET_REQUEST() so all processing is > > + * done on a local copy that cannot be modified by the other end. > > + * > > + * Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this > > + * to be ineffective where _req is a struct which consists of only bitfields. > > + */ > > +#define RING_COPY_REQUEST(_r, _idx, _req) do { \ > > + /* Use volatile to force the copy into _req. */ \ > > + *(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx); \ > > +} while (0) > > + > > +#define RING_GET_RESPONSE(_r, _idx) \ > > + (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp)) > > + > > +/* Loop termination condition: Would the specified index overflow the ring? */ > > +#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \ > > + (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r)) > > + > > +/* Ill-behaved frontend determination: Can there be this many requests? */ > > +#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \ > > + (((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r)) > > + > > +#define RING_PUSH_REQUESTS(_r) do { \ > > + xen_wmb(); /* back sees requests /before/ updated producer index */ \ > > + (_r)->sring->req_prod = (_r)->req_prod_pvt; \ > > +} while (0) > > + > > +#define RING_PUSH_RESPONSES(_r) do { \ > > + xen_wmb(); /* front sees resps /before/ updated producer index */ \ > > + (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ > > +} while (0) > > + > > +/* > > + * Notification hold-off (req_event and rsp_event): > > + * > > + * When queueing requests or responses on a shared ring, it may not always be > > + * necessary to notify the remote end. For example, if requests are in flight > > + * in a backend, the front may be able to queue further requests without > > + * notifying the back (if the back checks for new requests when it queues > > + * responses). > > + * > > + * When enqueuing requests or responses: > > + * > > + * Use RING_PUSH_{REQUESTS,RESPONSES}_AND_CHECK_NOTIFY(). The second argument > > + * is a boolean return value. True indicates that the receiver requires an > > + * asynchronous notification. > > + * > > + * After dequeuing requests or responses (before sleeping the connection): > > + * > > + * Use RING_FINAL_CHECK_FOR_REQUESTS() or RING_FINAL_CHECK_FOR_RESPONSES(). > > + * The second argument is a boolean return value. True indicates that there > > + * are pending messages on the ring (i.e., the connection should not be put > > + * to sleep). > > + * > > + * These macros will set the req_event/rsp_event field to trigger a > > + * notification on the very next message that is enqueued. If you want to > > + * create batches of work (i.e., only receive a notification after several > > + * messages have been enqueued) then you will need to create a customised > > + * version of the FINAL_CHECK macro in your own code, which sets the event > > + * field appropriately. > > + */ > > + > > +#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ > > + RING_IDX __old = (_r)->sring->req_prod; \ > > + RING_IDX __new = (_r)->req_prod_pvt; \ > > + xen_wmb(); /* back sees requests /before/ updated producer index */ \ > > + (_r)->sring->req_prod = __new; \ > > + xen_mb(); /* back sees new requests /before/ we check req_event */ \ > > + (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ > > + (RING_IDX)(__new - __old)); \ > > +} while (0) > > + > > +#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ > > + RING_IDX __old = (_r)->sring->rsp_prod; \ > > + RING_IDX __new = (_r)->rsp_prod_pvt; \ > > + xen_wmb(); /* front sees resps /before/ updated producer index */ \ > > + (_r)->sring->rsp_prod = __new; \ > > + xen_mb(); /* front sees new resps /before/ we check rsp_event */ \ > > + (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ > > + (RING_IDX)(__new - __old)); \ > > +} while (0) > > + > > +#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \ > > + (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ > > + if (_work_to_do) break; \ > > + (_r)->sring->req_event = (_r)->req_cons + 1; \ > > + xen_mb(); \ > > + (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ > > +} while (0) > > + > > +#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \ > > + (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ > > + if (_work_to_do) break; \ > > + (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ > > + xen_mb(); \ > > + (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ > > +} while (0) > > + > > + > > +/* > > + * DEFINE_XEN_FLEX_RING_AND_INTF defines two monodirectional rings and > > + * functions to check if there is data on the ring, and to read and > > + * write to them. > > + * > > + * DEFINE_XEN_FLEX_RING is similar to DEFINE_XEN_FLEX_RING_AND_INTF, but > > + * does not define the indexes page. As different protocols can have > > + * extensions to the basic format, this macro allow them to define their > > + * own struct. > > + * > > + * XEN_FLEX_RING_SIZE > > + * Convenience macro to calculate the size of one of the two rings > > + * from the overall order. > > + * > > + * $NAME_mask > > + * Function to apply the size mask to an index, to reduce the index > > + * within the range [0-size]. > > + * > > + * $NAME_read_packet > > + * Function to read data from the ring. The amount of data to read is > > + * specified by the "size" argument. > > + * > > + * $NAME_write_packet > > + * Function to write data to the ring. The amount of data to write is > > + * specified by the "size" argument. > > + * > > + * $NAME_get_ring_ptr > > + * Convenience function that returns a pointer to read/write to the > > + * ring at the right location. > > + * > > + * $NAME_data_intf > > + * Indexes page, shared between frontend and backend. It also > > + * contains the array of grant refs. > > + * > > + * $NAME_queued > > + * Function to calculate how many bytes are currently on the ring, > > + * ready to be read. It can also be used to calculate how much free > > + * space is currently on the ring (ring_size - $NAME_queued()). > > + */ > > +#define XEN_FLEX_RING_SIZE(order) \ > > + (1UL << (order + PAGE_SHIFT - 1)) > > + > > +#define DEFINE_XEN_FLEX_RING_AND_INTF(name) \ > > +struct name##_data_intf { \ > > + RING_IDX in_cons, in_prod; \ > > + \ > > + uint8_t pad1[56]; \ > > + \ > > + RING_IDX out_cons, out_prod; \ > > + \ > > + uint8_t pad2[56]; \ > > + \ > > + RING_IDX ring_order; \ > > + grant_ref_t ref[]; \ > > +}; \ > > +DEFINE_XEN_FLEX_RING(name); > > + > > +#define DEFINE_XEN_FLEX_RING(name) \ > > +static inline RING_IDX name##_mask(RING_IDX idx, RING_IDX ring_size) \ > > +{ \ > > + return (idx & (ring_size - 1)); \ > > +} \ > > + \ > > +static inline RING_IDX name##_mask_order(RING_IDX idx, RING_IDX ring_order) \ > > +{ \ > > + return (idx & (XEN_FLEX_RING_SIZE(ring_order) - 1)); \ > > +} \ > > + \ > > +static inline unsigned char* name##_get_ring_ptr(unsigned char *buf, \ > > + RING_IDX idx, \ > > + RING_IDX ring_order) \ > > +{ \ > > + return buf + name##_mask_order(idx, ring_order); \ > > +} \ > > + \ > > +static inline void name##_read_packet(const unsigned char *buf, \ > > + RING_IDX masked_prod, RING_IDX *masked_cons, \ > > + RING_IDX ring_size, void *opaque, size_t size) { \ > > + if (*masked_cons < masked_prod || \ > > + size <= ring_size - *masked_cons) { \ > > + memcpy(opaque, buf + *masked_cons, size); \ > > + } else { \ > > + memcpy(opaque, buf + *masked_cons, ring_size - *masked_cons); \ > > + memcpy((unsigned char *)opaque + ring_size - *masked_cons, buf, \ > > + size - (ring_size - *masked_cons)); \ > > + } \ > > + *masked_cons = name##_mask(*masked_cons + size, ring_size); \ > > +} \ > > + \ > > +static inline void name##_write_packet(unsigned char *buf, \ > > + RING_IDX *masked_prod, RING_IDX masked_cons, \ > > + RING_IDX ring_size, const void *opaque, size_t size) { \ > > + if (*masked_prod < masked_cons || \ > > + size <= ring_size - *masked_prod) { \ > > + memcpy(buf + *masked_prod, opaque, size); \ > > + } else { \ > > + memcpy(buf + *masked_prod, opaque, ring_size - *masked_prod); \ > > + memcpy(buf, (unsigned char *)opaque + (ring_size - *masked_prod), \ > > + size - (ring_size - *masked_prod)); \ > > + } \ > > + *masked_prod = name##_mask(*masked_prod + size, ring_size); \ > > +} \ > > + \ > > +struct name##_data { \ > > + unsigned char *in; /* half of the allocation */ \ > > + unsigned char *out; /* half of the allocation */ \ > > +}; \ > > + \ > > + \ > > +static inline RING_IDX name##_queued(RING_IDX prod, \ > > + RING_IDX cons, RING_IDX ring_size) \ > > +{ \ > > + RING_IDX size; \ > > + \ > > + if (prod == cons) \ > > + return 0; \ > > + \ > > + prod = name##_mask(prod, ring_size); \ > > + cons = name##_mask(cons, ring_size); \ > > + \ > > + if (prod == cons) \ > > + return ring_size; \ > > + \ > > + if (prod > cons) \ > > + size = prod - cons; \ > > + else \ > > + size = ring_size - (cons - prod); \ > > + return size; \ > > +}; > > + > > +#endif /* __XEN_PUBLIC_IO_RING_H__ */ > > + > > +/* > > + * Local variables: > > + * mode: C > > + * c-file-style: "BSD" > > + * c-basic-offset: 4 > > + * tab-width: 4 > > + * indent-tabs-mode: nil > > + * End: > > + */ > >
On Wed, 15 Mar 2017 11:36:12 -0700 (PDT) Stefano Stabellini <sstabellini@kernel.org> wrote: > On Wed, 15 Mar 2017, Greg Kurz wrote: > > On Mon, 13 Mar 2017 16:55:53 -0700 > > Stefano Stabellini <sstabellini@kernel.org> wrote: > > > > > Do not use the ring.h header installed on the system. Instead, import > > > the header into the QEMU codebase. This avoids problems when QEMU is > > > built against a Xen version too old to provide all the ring macros. > > > > > > > What kind of problems ? > > The FLEX macros are only available in Xen 4.9+ (still unreleased). > However, aside from these macros, the Xen 9pfs frontends and backends > could work fine on any Xen releases. In fact, the Xen public/io headers > are only provided as reference. > Ok. > > > > Signed-off-by: Stefano Stabellini <stefano@aporeto.com> > > > CC: anthony.perard@citrix.com > > > CC: jgross@suse.com > > > --- > > > NB: The new macros have not been committed to Xen yet. Do not apply this > > > patch until they do. > > > > Why ? Does this break compat with older Xen ? > > No, it does not break compatibility. But I think it is a good idea to > commit the header to QEMU only after the corresponding Xen header has > been accepted. I don't want the two to diverge. > Fair enough but this will put the entire patchset on hold then. When Xen 4.9 is supposed to be released ? > > > > --- > > > --- > > > hw/block/xen_blkif.h | 2 +- > > > hw/usb/xen-usb.c | 2 +- > > > include/hw/xen/io/ring.h | 455 +++++++++++++++++++++++++++++++++++++++++++++++ > > > 3 files changed, 457 insertions(+), 2 deletions(-) > > > create mode 100644 include/hw/xen/io/ring.h > > > > > > diff --git a/hw/block/xen_blkif.h b/hw/block/xen_blkif.h > > > index 3300b6f..3e6e1ea 100644 > > > --- a/hw/block/xen_blkif.h > > > +++ b/hw/block/xen_blkif.h > > > @@ -1,7 +1,7 @@ > > > #ifndef XEN_BLKIF_H > > > #define XEN_BLKIF_H > > > > > > -#include <xen/io/ring.h> > > > +#include "hw/xen/io/ring.h" > > > #include <xen/io/blkif.h> > > > #include <xen/io/protocols.h> > > > > > > diff --git a/hw/usb/xen-usb.c b/hw/usb/xen-usb.c > > > index 8e676e6..370b3d9 100644 > > > --- a/hw/usb/xen-usb.c > > > +++ b/hw/usb/xen-usb.c > > > @@ -33,7 +33,7 @@ > > > #include "qapi/qmp/qint.h" > > > #include "qapi/qmp/qstring.h" > > > > > > -#include <xen/io/ring.h> > > > +#include "hw/xen/io/ring.h" > > > #include <xen/io/usbif.h> > > > > > > /* > > > diff --git a/include/hw/xen/io/ring.h b/include/hw/xen/io/ring.h > > > new file mode 100644 > > > index 0000000..cf01fc3 > > > --- /dev/null > > > +++ b/include/hw/xen/io/ring.h > > > @@ -0,0 +1,455 @@ > > > +/****************************************************************************** > > > + * ring.h > > > + * > > > + * Shared producer-consumer ring macros. > > > + * > > > + * Permission is hereby granted, free of charge, to any person obtaining a copy > > > + * of this software and associated documentation files (the "Software"), to > > > + * deal in the Software without restriction, including without limitation the > > > + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or > > > + * sell copies of the Software, and to permit persons to whom the Software is > > > + * furnished to do so, subject to the following conditions: > > > + * > > > + * The above copyright notice and this permission notice shall be included in > > > + * all copies or substantial portions of the Software. > > > + * > > > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR > > > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, > > > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE > > > + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER > > > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING > > > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER > > > + * DEALINGS IN THE SOFTWARE. > > > + * > > > + * Tim Deegan and Andrew Warfield November 2004. > > > + */ > > > + > > > +#ifndef __XEN_PUBLIC_IO_RING_H__ > > > +#define __XEN_PUBLIC_IO_RING_H__ > > > + > > > +#if __XEN_INTERFACE_VERSION__ < 0x00030208 > > > +#define xen_mb() mb() > > > +#define xen_rmb() rmb() > > > +#define xen_wmb() wmb() > > > +#endif > > > + > > > +typedef unsigned int RING_IDX; > > > + > > > +/* Round a 32-bit unsigned constant down to the nearest power of two. */ > > > +#define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1)) > > > +#define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x)) > > > +#define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x)) > > > +#define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x)) > > > +#define __RD32(_x) (((_x) & 0xffff0000) ? __RD16((_x)>>16)<<16 : __RD16(_x)) > > > + > > > +/* > > > + * Calculate size of a shared ring, given the total available space for the > > > + * ring and indexes (_sz), and the name tag of the request/response structure. > > > + * A ring contains as many entries as will fit, rounded down to the nearest > > > + * power of two (so we can mask with (size-1) to loop around). > > > + */ > > > +#define __CONST_RING_SIZE(_s, _sz) \ > > > + (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \ > > > + sizeof(((struct _s##_sring *)0)->ring[0]))) > > > +/* > > > + * The same for passing in an actual pointer instead of a name tag. > > > + */ > > > +#define __RING_SIZE(_s, _sz) \ > > > + (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0]))) > > > + > > > +/* > > > + * Macros to make the correct C datatypes for a new kind of ring. > > > + * > > > + * To make a new ring datatype, you need to have two message structures, > > > + * let's say request_t, and response_t already defined. > > > + * > > > + * In a header where you want the ring datatype declared, you then do: > > > + * > > > + * DEFINE_RING_TYPES(mytag, request_t, response_t); > > > + * > > > + * These expand out to give you a set of types, as you can see below. > > > + * The most important of these are: > > > + * > > > + * mytag_sring_t - The shared ring. > > > + * mytag_front_ring_t - The 'front' half of the ring. > > > + * mytag_back_ring_t - The 'back' half of the ring. > > > + * > > > + * To initialize a ring in your code you need to know the location and size > > > + * of the shared memory area (PAGE_SIZE, for instance). To initialise > > > + * the front half: > > > + * > > > + * mytag_front_ring_t front_ring; > > > + * SHARED_RING_INIT((mytag_sring_t *)shared_page); > > > + * FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); > > > + * > > > + * Initializing the back follows similarly (note that only the front > > > + * initializes the shared ring): > > > + * > > > + * mytag_back_ring_t back_ring; > > > + * BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); > > > + */ > > > + > > > +#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \ > > > + \ > > > +/* Shared ring entry */ \ > > > +union __name##_sring_entry { \ > > > + __req_t req; \ > > > + __rsp_t rsp; \ > > > +}; \ > > > + \ > > > +/* Shared ring page */ \ > > > +struct __name##_sring { \ > > > + RING_IDX req_prod, req_event; \ > > > + RING_IDX rsp_prod, rsp_event; \ > > > + union { \ > > > + struct { \ > > > + uint8_t smartpoll_active; \ > > > + } netif; \ > > > + struct { \ > > > + uint8_t msg; \ > > > + } tapif_user; \ > > > + uint8_t pvt_pad[4]; \ > > > + } pvt; \ > > > + uint8_t __pad[44]; \ > > > + union __name##_sring_entry ring[1]; /* variable-length */ \ > > > +}; \ > > > + \ > > > +/* "Front" end's private variables */ \ > > > +struct __name##_front_ring { \ > > > + RING_IDX req_prod_pvt; \ > > > + RING_IDX rsp_cons; \ > > > + unsigned int nr_ents; \ > > > + struct __name##_sring *sring; \ > > > +}; \ > > > + \ > > > +/* "Back" end's private variables */ \ > > > +struct __name##_back_ring { \ > > > + RING_IDX rsp_prod_pvt; \ > > > + RING_IDX req_cons; \ > > > + unsigned int nr_ents; \ > > > + struct __name##_sring *sring; \ > > > +}; \ > > > + \ > > > +/* Syntactic sugar */ \ > > > +typedef struct __name##_sring __name##_sring_t; \ > > > +typedef struct __name##_front_ring __name##_front_ring_t; \ > > > +typedef struct __name##_back_ring __name##_back_ring_t > > > + > > > +/* > > > + * Macros for manipulating rings. > > > + * > > > + * FRONT_RING_whatever works on the "front end" of a ring: here > > > + * requests are pushed on to the ring and responses taken off it. > > > + * > > > + * BACK_RING_whatever works on the "back end" of a ring: here > > > + * requests are taken off the ring and responses put on. > > > + * > > > + * N.B. these macros do NO INTERLOCKS OR FLOW CONTROL. > > > + * This is OK in 1-for-1 request-response situations where the > > > + * requestor (front end) never has more than RING_SIZE()-1 > > > + * outstanding requests. > > > + */ > > > + > > > +/* Initialising empty rings */ > > > +#define SHARED_RING_INIT(_s) do { \ > > > + (_s)->req_prod = (_s)->rsp_prod = 0; \ > > > + (_s)->req_event = (_s)->rsp_event = 1; \ > > > + (void)memset((_s)->pvt.pvt_pad, 0, sizeof((_s)->pvt.pvt_pad)); \ > > > + (void)memset((_s)->__pad, 0, sizeof((_s)->__pad)); \ > > > +} while(0) > > > + > > > +#define FRONT_RING_INIT(_r, _s, __size) do { \ > > > + (_r)->req_prod_pvt = 0; \ > > > + (_r)->rsp_cons = 0; \ > > > + (_r)->nr_ents = __RING_SIZE(_s, __size); \ > > > + (_r)->sring = (_s); \ > > > +} while (0) > > > + > > > +#define BACK_RING_INIT(_r, _s, __size) do { \ > > > + (_r)->rsp_prod_pvt = 0; \ > > > + (_r)->req_cons = 0; \ > > > + (_r)->nr_ents = __RING_SIZE(_s, __size); \ > > > + (_r)->sring = (_s); \ > > > +} while (0) > > > + > > > +/* How big is this ring? */ > > > +#define RING_SIZE(_r) \ > > > + ((_r)->nr_ents) > > > + > > > +/* Number of free requests (for use on front side only). */ > > > +#define RING_FREE_REQUESTS(_r) \ > > > + (RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons)) > > > + > > > +/* Test if there is an empty slot available on the front ring. > > > + * (This is only meaningful from the front. ) > > > + */ > > > +#define RING_FULL(_r) \ > > > + (RING_FREE_REQUESTS(_r) == 0) > > > + > > > +/* Test if there are outstanding messages to be processed on a ring. */ > > > +#define RING_HAS_UNCONSUMED_RESPONSES(_r) \ > > > + ((_r)->sring->rsp_prod - (_r)->rsp_cons) > > > + > > > +#ifdef __GNUC__ > > > +#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \ > > > + unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \ > > > + unsigned int rsp = RING_SIZE(_r) - \ > > > + ((_r)->req_cons - (_r)->rsp_prod_pvt); \ > > > + req < rsp ? req : rsp; \ > > > +}) > > > +#else > > > +/* Same as above, but without the nice GCC ({ ... }) syntax. */ > > > +#define RING_HAS_UNCONSUMED_REQUESTS(_r) \ > > > + ((((_r)->sring->req_prod - (_r)->req_cons) < \ > > > + (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ? \ > > > + ((_r)->sring->req_prod - (_r)->req_cons) : \ > > > + (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) > > > +#endif > > > + > > > +/* Direct access to individual ring elements, by index. */ > > > +#define RING_GET_REQUEST(_r, _idx) \ > > > + (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) > > > + > > > +/* > > > + * Get a local copy of a request. > > > + * > > > + * Use this in preference to RING_GET_REQUEST() so all processing is > > > + * done on a local copy that cannot be modified by the other end. > > > + * > > > + * Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this > > > + * to be ineffective where _req is a struct which consists of only bitfields. > > > + */ > > > +#define RING_COPY_REQUEST(_r, _idx, _req) do { \ > > > + /* Use volatile to force the copy into _req. */ \ > > > + *(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx); \ > > > +} while (0) > > > + > > > +#define RING_GET_RESPONSE(_r, _idx) \ > > > + (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp)) > > > + > > > +/* Loop termination condition: Would the specified index overflow the ring? */ > > > +#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \ > > > + (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r)) > > > + > > > +/* Ill-behaved frontend determination: Can there be this many requests? */ > > > +#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \ > > > + (((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r)) > > > + > > > +#define RING_PUSH_REQUESTS(_r) do { \ > > > + xen_wmb(); /* back sees requests /before/ updated producer index */ \ > > > + (_r)->sring->req_prod = (_r)->req_prod_pvt; \ > > > +} while (0) > > > + > > > +#define RING_PUSH_RESPONSES(_r) do { \ > > > + xen_wmb(); /* front sees resps /before/ updated producer index */ \ > > > + (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ > > > +} while (0) > > > + > > > +/* > > > + * Notification hold-off (req_event and rsp_event): > > > + * > > > + * When queueing requests or responses on a shared ring, it may not always be > > > + * necessary to notify the remote end. For example, if requests are in flight > > > + * in a backend, the front may be able to queue further requests without > > > + * notifying the back (if the back checks for new requests when it queues > > > + * responses). > > > + * > > > + * When enqueuing requests or responses: > > > + * > > > + * Use RING_PUSH_{REQUESTS,RESPONSES}_AND_CHECK_NOTIFY(). The second argument > > > + * is a boolean return value. True indicates that the receiver requires an > > > + * asynchronous notification. > > > + * > > > + * After dequeuing requests or responses (before sleeping the connection): > > > + * > > > + * Use RING_FINAL_CHECK_FOR_REQUESTS() or RING_FINAL_CHECK_FOR_RESPONSES(). > > > + * The second argument is a boolean return value. True indicates that there > > > + * are pending messages on the ring (i.e., the connection should not be put > > > + * to sleep). > > > + * > > > + * These macros will set the req_event/rsp_event field to trigger a > > > + * notification on the very next message that is enqueued. If you want to > > > + * create batches of work (i.e., only receive a notification after several > > > + * messages have been enqueued) then you will need to create a customised > > > + * version of the FINAL_CHECK macro in your own code, which sets the event > > > + * field appropriately. > > > + */ > > > + > > > +#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ > > > + RING_IDX __old = (_r)->sring->req_prod; \ > > > + RING_IDX __new = (_r)->req_prod_pvt; \ > > > + xen_wmb(); /* back sees requests /before/ updated producer index */ \ > > > + (_r)->sring->req_prod = __new; \ > > > + xen_mb(); /* back sees new requests /before/ we check req_event */ \ > > > + (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ > > > + (RING_IDX)(__new - __old)); \ > > > +} while (0) > > > + > > > +#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ > > > + RING_IDX __old = (_r)->sring->rsp_prod; \ > > > + RING_IDX __new = (_r)->rsp_prod_pvt; \ > > > + xen_wmb(); /* front sees resps /before/ updated producer index */ \ > > > + (_r)->sring->rsp_prod = __new; \ > > > + xen_mb(); /* front sees new resps /before/ we check rsp_event */ \ > > > + (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ > > > + (RING_IDX)(__new - __old)); \ > > > +} while (0) > > > + > > > +#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \ > > > + (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ > > > + if (_work_to_do) break; \ > > > + (_r)->sring->req_event = (_r)->req_cons + 1; \ > > > + xen_mb(); \ > > > + (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ > > > +} while (0) > > > + > > > +#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \ > > > + (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ > > > + if (_work_to_do) break; \ > > > + (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ > > > + xen_mb(); \ > > > + (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ > > > +} while (0) > > > + > > > + > > > +/* > > > + * DEFINE_XEN_FLEX_RING_AND_INTF defines two monodirectional rings and > > > + * functions to check if there is data on the ring, and to read and > > > + * write to them. > > > + * > > > + * DEFINE_XEN_FLEX_RING is similar to DEFINE_XEN_FLEX_RING_AND_INTF, but > > > + * does not define the indexes page. As different protocols can have > > > + * extensions to the basic format, this macro allow them to define their > > > + * own struct. > > > + * > > > + * XEN_FLEX_RING_SIZE > > > + * Convenience macro to calculate the size of one of the two rings > > > + * from the overall order. > > > + * > > > + * $NAME_mask > > > + * Function to apply the size mask to an index, to reduce the index > > > + * within the range [0-size]. > > > + * > > > + * $NAME_read_packet > > > + * Function to read data from the ring. The amount of data to read is > > > + * specified by the "size" argument. > > > + * > > > + * $NAME_write_packet > > > + * Function to write data to the ring. The amount of data to write is > > > + * specified by the "size" argument. > > > + * > > > + * $NAME_get_ring_ptr > > > + * Convenience function that returns a pointer to read/write to the > > > + * ring at the right location. > > > + * > > > + * $NAME_data_intf > > > + * Indexes page, shared between frontend and backend. It also > > > + * contains the array of grant refs. > > > + * > > > + * $NAME_queued > > > + * Function to calculate how many bytes are currently on the ring, > > > + * ready to be read. It can also be used to calculate how much free > > > + * space is currently on the ring (ring_size - $NAME_queued()). > > > + */ > > > +#define XEN_FLEX_RING_SIZE(order) \ > > > + (1UL << (order + PAGE_SHIFT - 1)) > > > + > > > +#define DEFINE_XEN_FLEX_RING_AND_INTF(name) \ > > > +struct name##_data_intf { \ > > > + RING_IDX in_cons, in_prod; \ > > > + \ > > > + uint8_t pad1[56]; \ > > > + \ > > > + RING_IDX out_cons, out_prod; \ > > > + \ > > > + uint8_t pad2[56]; \ > > > + \ > > > + RING_IDX ring_order; \ > > > + grant_ref_t ref[]; \ > > > +}; \ > > > +DEFINE_XEN_FLEX_RING(name); > > > + > > > +#define DEFINE_XEN_FLEX_RING(name) \ > > > +static inline RING_IDX name##_mask(RING_IDX idx, RING_IDX ring_size) \ > > > +{ \ > > > + return (idx & (ring_size - 1)); \ > > > +} \ > > > + \ > > > +static inline RING_IDX name##_mask_order(RING_IDX idx, RING_IDX ring_order) \ > > > +{ \ > > > + return (idx & (XEN_FLEX_RING_SIZE(ring_order) - 1)); \ > > > +} \ > > > + \ > > > +static inline unsigned char* name##_get_ring_ptr(unsigned char *buf, \ > > > + RING_IDX idx, \ > > > + RING_IDX ring_order) \ > > > +{ \ > > > + return buf + name##_mask_order(idx, ring_order); \ > > > +} \ > > > + \ > > > +static inline void name##_read_packet(const unsigned char *buf, \ > > > + RING_IDX masked_prod, RING_IDX *masked_cons, \ > > > + RING_IDX ring_size, void *opaque, size_t size) { \ > > > + if (*masked_cons < masked_prod || \ > > > + size <= ring_size - *masked_cons) { \ > > > + memcpy(opaque, buf + *masked_cons, size); \ > > > + } else { \ > > > + memcpy(opaque, buf + *masked_cons, ring_size - *masked_cons); \ > > > + memcpy((unsigned char *)opaque + ring_size - *masked_cons, buf, \ > > > + size - (ring_size - *masked_cons)); \ > > > + } \ > > > + *masked_cons = name##_mask(*masked_cons + size, ring_size); \ > > > +} \ > > > + \ > > > +static inline void name##_write_packet(unsigned char *buf, \ > > > + RING_IDX *masked_prod, RING_IDX masked_cons, \ > > > + RING_IDX ring_size, const void *opaque, size_t size) { \ > > > + if (*masked_prod < masked_cons || \ > > > + size <= ring_size - *masked_prod) { \ > > > + memcpy(buf + *masked_prod, opaque, size); \ > > > + } else { \ > > > + memcpy(buf + *masked_prod, opaque, ring_size - *masked_prod); \ > > > + memcpy(buf, (unsigned char *)opaque + (ring_size - *masked_prod), \ > > > + size - (ring_size - *masked_prod)); \ > > > + } \ > > > + *masked_prod = name##_mask(*masked_prod + size, ring_size); \ > > > +} \ > > > + \ > > > +struct name##_data { \ > > > + unsigned char *in; /* half of the allocation */ \ > > > + unsigned char *out; /* half of the allocation */ \ > > > +}; \ > > > + \ > > > + \ > > > +static inline RING_IDX name##_queued(RING_IDX prod, \ > > > + RING_IDX cons, RING_IDX ring_size) \ > > > +{ \ > > > + RING_IDX size; \ > > > + \ > > > + if (prod == cons) \ > > > + return 0; \ > > > + \ > > > + prod = name##_mask(prod, ring_size); \ > > > + cons = name##_mask(cons, ring_size); \ > > > + \ > > > + if (prod == cons) \ > > > + return ring_size; \ > > > + \ > > > + if (prod > cons) \ > > > + size = prod - cons; \ > > > + else \ > > > + size = ring_size - (cons - prod); \ > > > + return size; \ > > > +}; > > > + > > > +#endif /* __XEN_PUBLIC_IO_RING_H__ */ > > > + > > > +/* > > > + * Local variables: > > > + * mode: C > > > + * c-file-style: "BSD" > > > + * c-basic-offset: 4 > > > + * tab-width: 4 > > > + * indent-tabs-mode: nil > > > + * End: > > > + */ > > > >
On Wed, 15 Mar 2017, Greg Kurz wrote: > On Wed, 15 Mar 2017 11:36:12 -0700 (PDT) > Stefano Stabellini <sstabellini@kernel.org> wrote: > > > On Wed, 15 Mar 2017, Greg Kurz wrote: > > > On Mon, 13 Mar 2017 16:55:53 -0700 > > > Stefano Stabellini <sstabellini@kernel.org> wrote: > > > > > > > Do not use the ring.h header installed on the system. Instead, import > > > > the header into the QEMU codebase. This avoids problems when QEMU is > > > > built against a Xen version too old to provide all the ring macros. > > > > > > > > > > What kind of problems ? > > > > The FLEX macros are only available in Xen 4.9+ (still unreleased). > > However, aside from these macros, the Xen 9pfs frontends and backends > > could work fine on any Xen releases. In fact, the Xen public/io headers > > are only provided as reference. > > > > Ok. > > > > > > > Signed-off-by: Stefano Stabellini <stefano@aporeto.com> > > > > CC: anthony.perard@citrix.com > > > > CC: jgross@suse.com > > > > --- > > > > NB: The new macros have not been committed to Xen yet. Do not apply this > > > > patch until they do. > > > > > > Why ? Does this break compat with older Xen ? > > > > No, it does not break compatibility. But I think it is a good idea to > > commit the header to QEMU only after the corresponding Xen header has > > been accepted. I don't want the two to diverge. > > > > Fair enough but this will put the entire patchset on hold then. When Xen 4.9 > is supposed to be released ? In a few months, but I don't think we need to wait until the release, just for the reviewed-by on the new macros, that should come soon. > > > > --- > > > > --- > > > > hw/block/xen_blkif.h | 2 +- > > > > hw/usb/xen-usb.c | 2 +- > > > > include/hw/xen/io/ring.h | 455 +++++++++++++++++++++++++++++++++++++++++++++++ > > > > 3 files changed, 457 insertions(+), 2 deletions(-) > > > > create mode 100644 include/hw/xen/io/ring.h > > > > > > > > diff --git a/hw/block/xen_blkif.h b/hw/block/xen_blkif.h > > > > index 3300b6f..3e6e1ea 100644 > > > > --- a/hw/block/xen_blkif.h > > > > +++ b/hw/block/xen_blkif.h > > > > @@ -1,7 +1,7 @@ > > > > #ifndef XEN_BLKIF_H > > > > #define XEN_BLKIF_H > > > > > > > > -#include <xen/io/ring.h> > > > > +#include "hw/xen/io/ring.h" > > > > #include <xen/io/blkif.h> > > > > #include <xen/io/protocols.h> > > > > > > > > diff --git a/hw/usb/xen-usb.c b/hw/usb/xen-usb.c > > > > index 8e676e6..370b3d9 100644 > > > > --- a/hw/usb/xen-usb.c > > > > +++ b/hw/usb/xen-usb.c > > > > @@ -33,7 +33,7 @@ > > > > #include "qapi/qmp/qint.h" > > > > #include "qapi/qmp/qstring.h" > > > > > > > > -#include <xen/io/ring.h> > > > > +#include "hw/xen/io/ring.h" > > > > #include <xen/io/usbif.h> > > > > > > > > /* > > > > diff --git a/include/hw/xen/io/ring.h b/include/hw/xen/io/ring.h > > > > new file mode 100644 > > > > index 0000000..cf01fc3 > > > > --- /dev/null > > > > +++ b/include/hw/xen/io/ring.h > > > > @@ -0,0 +1,455 @@ > > > > +/****************************************************************************** > > > > + * ring.h > > > > + * > > > > + * Shared producer-consumer ring macros. > > > > + * > > > > + * Permission is hereby granted, free of charge, to any person obtaining a copy > > > > + * of this software and associated documentation files (the "Software"), to > > > > + * deal in the Software without restriction, including without limitation the > > > > + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or > > > > + * sell copies of the Software, and to permit persons to whom the Software is > > > > + * furnished to do so, subject to the following conditions: > > > > + * > > > > + * The above copyright notice and this permission notice shall be included in > > > > + * all copies or substantial portions of the Software. > > > > + * > > > > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR > > > > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, > > > > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE > > > > + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER > > > > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING > > > > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER > > > > + * DEALINGS IN THE SOFTWARE. > > > > + * > > > > + * Tim Deegan and Andrew Warfield November 2004. > > > > + */ > > > > + > > > > +#ifndef __XEN_PUBLIC_IO_RING_H__ > > > > +#define __XEN_PUBLIC_IO_RING_H__ > > > > + > > > > +#if __XEN_INTERFACE_VERSION__ < 0x00030208 > > > > +#define xen_mb() mb() > > > > +#define xen_rmb() rmb() > > > > +#define xen_wmb() wmb() > > > > +#endif > > > > + > > > > +typedef unsigned int RING_IDX; > > > > + > > > > +/* Round a 32-bit unsigned constant down to the nearest power of two. */ > > > > +#define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1)) > > > > +#define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x)) > > > > +#define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x)) > > > > +#define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x)) > > > > +#define __RD32(_x) (((_x) & 0xffff0000) ? __RD16((_x)>>16)<<16 : __RD16(_x)) > > > > + > > > > +/* > > > > + * Calculate size of a shared ring, given the total available space for the > > > > + * ring and indexes (_sz), and the name tag of the request/response structure. > > > > + * A ring contains as many entries as will fit, rounded down to the nearest > > > > + * power of two (so we can mask with (size-1) to loop around). > > > > + */ > > > > +#define __CONST_RING_SIZE(_s, _sz) \ > > > > + (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \ > > > > + sizeof(((struct _s##_sring *)0)->ring[0]))) > > > > +/* > > > > + * The same for passing in an actual pointer instead of a name tag. > > > > + */ > > > > +#define __RING_SIZE(_s, _sz) \ > > > > + (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0]))) > > > > + > > > > +/* > > > > + * Macros to make the correct C datatypes for a new kind of ring. > > > > + * > > > > + * To make a new ring datatype, you need to have two message structures, > > > > + * let's say request_t, and response_t already defined. > > > > + * > > > > + * In a header where you want the ring datatype declared, you then do: > > > > + * > > > > + * DEFINE_RING_TYPES(mytag, request_t, response_t); > > > > + * > > > > + * These expand out to give you a set of types, as you can see below. > > > > + * The most important of these are: > > > > + * > > > > + * mytag_sring_t - The shared ring. > > > > + * mytag_front_ring_t - The 'front' half of the ring. > > > > + * mytag_back_ring_t - The 'back' half of the ring. > > > > + * > > > > + * To initialize a ring in your code you need to know the location and size > > > > + * of the shared memory area (PAGE_SIZE, for instance). To initialise > > > > + * the front half: > > > > + * > > > > + * mytag_front_ring_t front_ring; > > > > + * SHARED_RING_INIT((mytag_sring_t *)shared_page); > > > > + * FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); > > > > + * > > > > + * Initializing the back follows similarly (note that only the front > > > > + * initializes the shared ring): > > > > + * > > > > + * mytag_back_ring_t back_ring; > > > > + * BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); > > > > + */ > > > > + > > > > +#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \ > > > > + \ > > > > +/* Shared ring entry */ \ > > > > +union __name##_sring_entry { \ > > > > + __req_t req; \ > > > > + __rsp_t rsp; \ > > > > +}; \ > > > > + \ > > > > +/* Shared ring page */ \ > > > > +struct __name##_sring { \ > > > > + RING_IDX req_prod, req_event; \ > > > > + RING_IDX rsp_prod, rsp_event; \ > > > > + union { \ > > > > + struct { \ > > > > + uint8_t smartpoll_active; \ > > > > + } netif; \ > > > > + struct { \ > > > > + uint8_t msg; \ > > > > + } tapif_user; \ > > > > + uint8_t pvt_pad[4]; \ > > > > + } pvt; \ > > > > + uint8_t __pad[44]; \ > > > > + union __name##_sring_entry ring[1]; /* variable-length */ \ > > > > +}; \ > > > > + \ > > > > +/* "Front" end's private variables */ \ > > > > +struct __name##_front_ring { \ > > > > + RING_IDX req_prod_pvt; \ > > > > + RING_IDX rsp_cons; \ > > > > + unsigned int nr_ents; \ > > > > + struct __name##_sring *sring; \ > > > > +}; \ > > > > + \ > > > > +/* "Back" end's private variables */ \ > > > > +struct __name##_back_ring { \ > > > > + RING_IDX rsp_prod_pvt; \ > > > > + RING_IDX req_cons; \ > > > > + unsigned int nr_ents; \ > > > > + struct __name##_sring *sring; \ > > > > +}; \ > > > > + \ > > > > +/* Syntactic sugar */ \ > > > > +typedef struct __name##_sring __name##_sring_t; \ > > > > +typedef struct __name##_front_ring __name##_front_ring_t; \ > > > > +typedef struct __name##_back_ring __name##_back_ring_t > > > > + > > > > +/* > > > > + * Macros for manipulating rings. > > > > + * > > > > + * FRONT_RING_whatever works on the "front end" of a ring: here > > > > + * requests are pushed on to the ring and responses taken off it. > > > > + * > > > > + * BACK_RING_whatever works on the "back end" of a ring: here > > > > + * requests are taken off the ring and responses put on. > > > > + * > > > > + * N.B. these macros do NO INTERLOCKS OR FLOW CONTROL. > > > > + * This is OK in 1-for-1 request-response situations where the > > > > + * requestor (front end) never has more than RING_SIZE()-1 > > > > + * outstanding requests. > > > > + */ > > > > + > > > > +/* Initialising empty rings */ > > > > +#define SHARED_RING_INIT(_s) do { \ > > > > + (_s)->req_prod = (_s)->rsp_prod = 0; \ > > > > + (_s)->req_event = (_s)->rsp_event = 1; \ > > > > + (void)memset((_s)->pvt.pvt_pad, 0, sizeof((_s)->pvt.pvt_pad)); \ > > > > + (void)memset((_s)->__pad, 0, sizeof((_s)->__pad)); \ > > > > +} while(0) > > > > + > > > > +#define FRONT_RING_INIT(_r, _s, __size) do { \ > > > > + (_r)->req_prod_pvt = 0; \ > > > > + (_r)->rsp_cons = 0; \ > > > > + (_r)->nr_ents = __RING_SIZE(_s, __size); \ > > > > + (_r)->sring = (_s); \ > > > > +} while (0) > > > > + > > > > +#define BACK_RING_INIT(_r, _s, __size) do { \ > > > > + (_r)->rsp_prod_pvt = 0; \ > > > > + (_r)->req_cons = 0; \ > > > > + (_r)->nr_ents = __RING_SIZE(_s, __size); \ > > > > + (_r)->sring = (_s); \ > > > > +} while (0) > > > > + > > > > +/* How big is this ring? */ > > > > +#define RING_SIZE(_r) \ > > > > + ((_r)->nr_ents) > > > > + > > > > +/* Number of free requests (for use on front side only). */ > > > > +#define RING_FREE_REQUESTS(_r) \ > > > > + (RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons)) > > > > + > > > > +/* Test if there is an empty slot available on the front ring. > > > > + * (This is only meaningful from the front. ) > > > > + */ > > > > +#define RING_FULL(_r) \ > > > > + (RING_FREE_REQUESTS(_r) == 0) > > > > + > > > > +/* Test if there are outstanding messages to be processed on a ring. */ > > > > +#define RING_HAS_UNCONSUMED_RESPONSES(_r) \ > > > > + ((_r)->sring->rsp_prod - (_r)->rsp_cons) > > > > + > > > > +#ifdef __GNUC__ > > > > +#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \ > > > > + unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \ > > > > + unsigned int rsp = RING_SIZE(_r) - \ > > > > + ((_r)->req_cons - (_r)->rsp_prod_pvt); \ > > > > + req < rsp ? req : rsp; \ > > > > +}) > > > > +#else > > > > +/* Same as above, but without the nice GCC ({ ... }) syntax. */ > > > > +#define RING_HAS_UNCONSUMED_REQUESTS(_r) \ > > > > + ((((_r)->sring->req_prod - (_r)->req_cons) < \ > > > > + (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ? \ > > > > + ((_r)->sring->req_prod - (_r)->req_cons) : \ > > > > + (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) > > > > +#endif > > > > + > > > > +/* Direct access to individual ring elements, by index. */ > > > > +#define RING_GET_REQUEST(_r, _idx) \ > > > > + (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) > > > > + > > > > +/* > > > > + * Get a local copy of a request. > > > > + * > > > > + * Use this in preference to RING_GET_REQUEST() so all processing is > > > > + * done on a local copy that cannot be modified by the other end. > > > > + * > > > > + * Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this > > > > + * to be ineffective where _req is a struct which consists of only bitfields. > > > > + */ > > > > +#define RING_COPY_REQUEST(_r, _idx, _req) do { \ > > > > + /* Use volatile to force the copy into _req. */ \ > > > > + *(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx); \ > > > > +} while (0) > > > > + > > > > +#define RING_GET_RESPONSE(_r, _idx) \ > > > > + (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp)) > > > > + > > > > +/* Loop termination condition: Would the specified index overflow the ring? */ > > > > +#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \ > > > > + (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r)) > > > > + > > > > +/* Ill-behaved frontend determination: Can there be this many requests? */ > > > > +#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \ > > > > + (((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r)) > > > > + > > > > +#define RING_PUSH_REQUESTS(_r) do { \ > > > > + xen_wmb(); /* back sees requests /before/ updated producer index */ \ > > > > + (_r)->sring->req_prod = (_r)->req_prod_pvt; \ > > > > +} while (0) > > > > + > > > > +#define RING_PUSH_RESPONSES(_r) do { \ > > > > + xen_wmb(); /* front sees resps /before/ updated producer index */ \ > > > > + (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ > > > > +} while (0) > > > > + > > > > +/* > > > > + * Notification hold-off (req_event and rsp_event): > > > > + * > > > > + * When queueing requests or responses on a shared ring, it may not always be > > > > + * necessary to notify the remote end. For example, if requests are in flight > > > > + * in a backend, the front may be able to queue further requests without > > > > + * notifying the back (if the back checks for new requests when it queues > > > > + * responses). > > > > + * > > > > + * When enqueuing requests or responses: > > > > + * > > > > + * Use RING_PUSH_{REQUESTS,RESPONSES}_AND_CHECK_NOTIFY(). The second argument > > > > + * is a boolean return value. True indicates that the receiver requires an > > > > + * asynchronous notification. > > > > + * > > > > + * After dequeuing requests or responses (before sleeping the connection): > > > > + * > > > > + * Use RING_FINAL_CHECK_FOR_REQUESTS() or RING_FINAL_CHECK_FOR_RESPONSES(). > > > > + * The second argument is a boolean return value. True indicates that there > > > > + * are pending messages on the ring (i.e., the connection should not be put > > > > + * to sleep). > > > > + * > > > > + * These macros will set the req_event/rsp_event field to trigger a > > > > + * notification on the very next message that is enqueued. If you want to > > > > + * create batches of work (i.e., only receive a notification after several > > > > + * messages have been enqueued) then you will need to create a customised > > > > + * version of the FINAL_CHECK macro in your own code, which sets the event > > > > + * field appropriately. > > > > + */ > > > > + > > > > +#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ > > > > + RING_IDX __old = (_r)->sring->req_prod; \ > > > > + RING_IDX __new = (_r)->req_prod_pvt; \ > > > > + xen_wmb(); /* back sees requests /before/ updated producer index */ \ > > > > + (_r)->sring->req_prod = __new; \ > > > > + xen_mb(); /* back sees new requests /before/ we check req_event */ \ > > > > + (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ > > > > + (RING_IDX)(__new - __old)); \ > > > > +} while (0) > > > > + > > > > +#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ > > > > + RING_IDX __old = (_r)->sring->rsp_prod; \ > > > > + RING_IDX __new = (_r)->rsp_prod_pvt; \ > > > > + xen_wmb(); /* front sees resps /before/ updated producer index */ \ > > > > + (_r)->sring->rsp_prod = __new; \ > > > > + xen_mb(); /* front sees new resps /before/ we check rsp_event */ \ > > > > + (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ > > > > + (RING_IDX)(__new - __old)); \ > > > > +} while (0) > > > > + > > > > +#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \ > > > > + (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ > > > > + if (_work_to_do) break; \ > > > > + (_r)->sring->req_event = (_r)->req_cons + 1; \ > > > > + xen_mb(); \ > > > > + (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ > > > > +} while (0) > > > > + > > > > +#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \ > > > > + (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ > > > > + if (_work_to_do) break; \ > > > > + (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ > > > > + xen_mb(); \ > > > > + (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ > > > > +} while (0) > > > > + > > > > + > > > > +/* > > > > + * DEFINE_XEN_FLEX_RING_AND_INTF defines two monodirectional rings and > > > > + * functions to check if there is data on the ring, and to read and > > > > + * write to them. > > > > + * > > > > + * DEFINE_XEN_FLEX_RING is similar to DEFINE_XEN_FLEX_RING_AND_INTF, but > > > > + * does not define the indexes page. As different protocols can have > > > > + * extensions to the basic format, this macro allow them to define their > > > > + * own struct. > > > > + * > > > > + * XEN_FLEX_RING_SIZE > > > > + * Convenience macro to calculate the size of one of the two rings > > > > + * from the overall order. > > > > + * > > > > + * $NAME_mask > > > > + * Function to apply the size mask to an index, to reduce the index > > > > + * within the range [0-size]. > > > > + * > > > > + * $NAME_read_packet > > > > + * Function to read data from the ring. The amount of data to read is > > > > + * specified by the "size" argument. > > > > + * > > > > + * $NAME_write_packet > > > > + * Function to write data to the ring. The amount of data to write is > > > > + * specified by the "size" argument. > > > > + * > > > > + * $NAME_get_ring_ptr > > > > + * Convenience function that returns a pointer to read/write to the > > > > + * ring at the right location. > > > > + * > > > > + * $NAME_data_intf > > > > + * Indexes page, shared between frontend and backend. It also > > > > + * contains the array of grant refs. > > > > + * > > > > + * $NAME_queued > > > > + * Function to calculate how many bytes are currently on the ring, > > > > + * ready to be read. It can also be used to calculate how much free > > > > + * space is currently on the ring (ring_size - $NAME_queued()). > > > > + */ > > > > +#define XEN_FLEX_RING_SIZE(order) \ > > > > + (1UL << (order + PAGE_SHIFT - 1)) > > > > + > > > > +#define DEFINE_XEN_FLEX_RING_AND_INTF(name) \ > > > > +struct name##_data_intf { \ > > > > + RING_IDX in_cons, in_prod; \ > > > > + \ > > > > + uint8_t pad1[56]; \ > > > > + \ > > > > + RING_IDX out_cons, out_prod; \ > > > > + \ > > > > + uint8_t pad2[56]; \ > > > > + \ > > > > + RING_IDX ring_order; \ > > > > + grant_ref_t ref[]; \ > > > > +}; \ > > > > +DEFINE_XEN_FLEX_RING(name); > > > > + > > > > +#define DEFINE_XEN_FLEX_RING(name) \ > > > > +static inline RING_IDX name##_mask(RING_IDX idx, RING_IDX ring_size) \ > > > > +{ \ > > > > + return (idx & (ring_size - 1)); \ > > > > +} \ > > > > + \ > > > > +static inline RING_IDX name##_mask_order(RING_IDX idx, RING_IDX ring_order) \ > > > > +{ \ > > > > + return (idx & (XEN_FLEX_RING_SIZE(ring_order) - 1)); \ > > > > +} \ > > > > + \ > > > > +static inline unsigned char* name##_get_ring_ptr(unsigned char *buf, \ > > > > + RING_IDX idx, \ > > > > + RING_IDX ring_order) \ > > > > +{ \ > > > > + return buf + name##_mask_order(idx, ring_order); \ > > > > +} \ > > > > + \ > > > > +static inline void name##_read_packet(const unsigned char *buf, \ > > > > + RING_IDX masked_prod, RING_IDX *masked_cons, \ > > > > + RING_IDX ring_size, void *opaque, size_t size) { \ > > > > + if (*masked_cons < masked_prod || \ > > > > + size <= ring_size - *masked_cons) { \ > > > > + memcpy(opaque, buf + *masked_cons, size); \ > > > > + } else { \ > > > > + memcpy(opaque, buf + *masked_cons, ring_size - *masked_cons); \ > > > > + memcpy((unsigned char *)opaque + ring_size - *masked_cons, buf, \ > > > > + size - (ring_size - *masked_cons)); \ > > > > + } \ > > > > + *masked_cons = name##_mask(*masked_cons + size, ring_size); \ > > > > +} \ > > > > + \ > > > > +static inline void name##_write_packet(unsigned char *buf, \ > > > > + RING_IDX *masked_prod, RING_IDX masked_cons, \ > > > > + RING_IDX ring_size, const void *opaque, size_t size) { \ > > > > + if (*masked_prod < masked_cons || \ > > > > + size <= ring_size - *masked_prod) { \ > > > > + memcpy(buf + *masked_prod, opaque, size); \ > > > > + } else { \ > > > > + memcpy(buf + *masked_prod, opaque, ring_size - *masked_prod); \ > > > > + memcpy(buf, (unsigned char *)opaque + (ring_size - *masked_prod), \ > > > > + size - (ring_size - *masked_prod)); \ > > > > + } \ > > > > + *masked_prod = name##_mask(*masked_prod + size, ring_size); \ > > > > +} \ > > > > + \ > > > > +struct name##_data { \ > > > > + unsigned char *in; /* half of the allocation */ \ > > > > + unsigned char *out; /* half of the allocation */ \ > > > > +}; \ > > > > + \ > > > > + \ > > > > +static inline RING_IDX name##_queued(RING_IDX prod, \ > > > > + RING_IDX cons, RING_IDX ring_size) \ > > > > +{ \ > > > > + RING_IDX size; \ > > > > + \ > > > > + if (prod == cons) \ > > > > + return 0; \ > > > > + \ > > > > + prod = name##_mask(prod, ring_size); \ > > > > + cons = name##_mask(cons, ring_size); \ > > > > + \ > > > > + if (prod == cons) \ > > > > + return ring_size; \ > > > > + \ > > > > + if (prod > cons) \ > > > > + size = prod - cons; \ > > > > + else \ > > > > + size = ring_size - (cons - prod); \ > > > > + return size; \ > > > > +}; > > > > + > > > > +#endif /* __XEN_PUBLIC_IO_RING_H__ */ > > > > + > > > > +/* > > > > + * Local variables: > > > > + * mode: C > > > > + * c-file-style: "BSD" > > > > + * c-basic-offset: 4 > > > > + * tab-width: 4 > > > > + * indent-tabs-mode: nil > > > > + * End: > > > > + */ > > > > > > > >
diff --git a/hw/block/xen_blkif.h b/hw/block/xen_blkif.h index 3300b6f..3e6e1ea 100644 --- a/hw/block/xen_blkif.h +++ b/hw/block/xen_blkif.h @@ -1,7 +1,7 @@ #ifndef XEN_BLKIF_H #define XEN_BLKIF_H -#include <xen/io/ring.h> +#include "hw/xen/io/ring.h" #include <xen/io/blkif.h> #include <xen/io/protocols.h> diff --git a/hw/usb/xen-usb.c b/hw/usb/xen-usb.c index 8e676e6..370b3d9 100644 --- a/hw/usb/xen-usb.c +++ b/hw/usb/xen-usb.c @@ -33,7 +33,7 @@ #include "qapi/qmp/qint.h" #include "qapi/qmp/qstring.h" -#include <xen/io/ring.h> +#include "hw/xen/io/ring.h" #include <xen/io/usbif.h> /* diff --git a/include/hw/xen/io/ring.h b/include/hw/xen/io/ring.h new file mode 100644 index 0000000..cf01fc3 --- /dev/null +++ b/include/hw/xen/io/ring.h @@ -0,0 +1,455 @@ +/****************************************************************************** + * ring.h + * + * Shared producer-consumer ring macros. + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to + * deal in the Software without restriction, including without limitation the + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or + * sell copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER + * DEALINGS IN THE SOFTWARE. + * + * Tim Deegan and Andrew Warfield November 2004. + */ + +#ifndef __XEN_PUBLIC_IO_RING_H__ +#define __XEN_PUBLIC_IO_RING_H__ + +#if __XEN_INTERFACE_VERSION__ < 0x00030208 +#define xen_mb() mb() +#define xen_rmb() rmb() +#define xen_wmb() wmb() +#endif + +typedef unsigned int RING_IDX; + +/* Round a 32-bit unsigned constant down to the nearest power of two. */ +#define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1)) +#define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x)) +#define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x)) +#define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x)) +#define __RD32(_x) (((_x) & 0xffff0000) ? __RD16((_x)>>16)<<16 : __RD16(_x)) + +/* + * Calculate size of a shared ring, given the total available space for the + * ring and indexes (_sz), and the name tag of the request/response structure. + * A ring contains as many entries as will fit, rounded down to the nearest + * power of two (so we can mask with (size-1) to loop around). + */ +#define __CONST_RING_SIZE(_s, _sz) \ + (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \ + sizeof(((struct _s##_sring *)0)->ring[0]))) +/* + * The same for passing in an actual pointer instead of a name tag. + */ +#define __RING_SIZE(_s, _sz) \ + (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0]))) + +/* + * Macros to make the correct C datatypes for a new kind of ring. + * + * To make a new ring datatype, you need to have two message structures, + * let's say request_t, and response_t already defined. + * + * In a header where you want the ring datatype declared, you then do: + * + * DEFINE_RING_TYPES(mytag, request_t, response_t); + * + * These expand out to give you a set of types, as you can see below. + * The most important of these are: + * + * mytag_sring_t - The shared ring. + * mytag_front_ring_t - The 'front' half of the ring. + * mytag_back_ring_t - The 'back' half of the ring. + * + * To initialize a ring in your code you need to know the location and size + * of the shared memory area (PAGE_SIZE, for instance). To initialise + * the front half: + * + * mytag_front_ring_t front_ring; + * SHARED_RING_INIT((mytag_sring_t *)shared_page); + * FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); + * + * Initializing the back follows similarly (note that only the front + * initializes the shared ring): + * + * mytag_back_ring_t back_ring; + * BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE); + */ + +#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \ + \ +/* Shared ring entry */ \ +union __name##_sring_entry { \ + __req_t req; \ + __rsp_t rsp; \ +}; \ + \ +/* Shared ring page */ \ +struct __name##_sring { \ + RING_IDX req_prod, req_event; \ + RING_IDX rsp_prod, rsp_event; \ + union { \ + struct { \ + uint8_t smartpoll_active; \ + } netif; \ + struct { \ + uint8_t msg; \ + } tapif_user; \ + uint8_t pvt_pad[4]; \ + } pvt; \ + uint8_t __pad[44]; \ + union __name##_sring_entry ring[1]; /* variable-length */ \ +}; \ + \ +/* "Front" end's private variables */ \ +struct __name##_front_ring { \ + RING_IDX req_prod_pvt; \ + RING_IDX rsp_cons; \ + unsigned int nr_ents; \ + struct __name##_sring *sring; \ +}; \ + \ +/* "Back" end's private variables */ \ +struct __name##_back_ring { \ + RING_IDX rsp_prod_pvt; \ + RING_IDX req_cons; \ + unsigned int nr_ents; \ + struct __name##_sring *sring; \ +}; \ + \ +/* Syntactic sugar */ \ +typedef struct __name##_sring __name##_sring_t; \ +typedef struct __name##_front_ring __name##_front_ring_t; \ +typedef struct __name##_back_ring __name##_back_ring_t + +/* + * Macros for manipulating rings. + * + * FRONT_RING_whatever works on the "front end" of a ring: here + * requests are pushed on to the ring and responses taken off it. + * + * BACK_RING_whatever works on the "back end" of a ring: here + * requests are taken off the ring and responses put on. + * + * N.B. these macros do NO INTERLOCKS OR FLOW CONTROL. + * This is OK in 1-for-1 request-response situations where the + * requestor (front end) never has more than RING_SIZE()-1 + * outstanding requests. + */ + +/* Initialising empty rings */ +#define SHARED_RING_INIT(_s) do { \ + (_s)->req_prod = (_s)->rsp_prod = 0; \ + (_s)->req_event = (_s)->rsp_event = 1; \ + (void)memset((_s)->pvt.pvt_pad, 0, sizeof((_s)->pvt.pvt_pad)); \ + (void)memset((_s)->__pad, 0, sizeof((_s)->__pad)); \ +} while(0) + +#define FRONT_RING_INIT(_r, _s, __size) do { \ + (_r)->req_prod_pvt = 0; \ + (_r)->rsp_cons = 0; \ + (_r)->nr_ents = __RING_SIZE(_s, __size); \ + (_r)->sring = (_s); \ +} while (0) + +#define BACK_RING_INIT(_r, _s, __size) do { \ + (_r)->rsp_prod_pvt = 0; \ + (_r)->req_cons = 0; \ + (_r)->nr_ents = __RING_SIZE(_s, __size); \ + (_r)->sring = (_s); \ +} while (0) + +/* How big is this ring? */ +#define RING_SIZE(_r) \ + ((_r)->nr_ents) + +/* Number of free requests (for use on front side only). */ +#define RING_FREE_REQUESTS(_r) \ + (RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons)) + +/* Test if there is an empty slot available on the front ring. + * (This is only meaningful from the front. ) + */ +#define RING_FULL(_r) \ + (RING_FREE_REQUESTS(_r) == 0) + +/* Test if there are outstanding messages to be processed on a ring. */ +#define RING_HAS_UNCONSUMED_RESPONSES(_r) \ + ((_r)->sring->rsp_prod - (_r)->rsp_cons) + +#ifdef __GNUC__ +#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \ + unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \ + unsigned int rsp = RING_SIZE(_r) - \ + ((_r)->req_cons - (_r)->rsp_prod_pvt); \ + req < rsp ? req : rsp; \ +}) +#else +/* Same as above, but without the nice GCC ({ ... }) syntax. */ +#define RING_HAS_UNCONSUMED_REQUESTS(_r) \ + ((((_r)->sring->req_prod - (_r)->req_cons) < \ + (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) ? \ + ((_r)->sring->req_prod - (_r)->req_cons) : \ + (RING_SIZE(_r) - ((_r)->req_cons - (_r)->rsp_prod_pvt))) +#endif + +/* Direct access to individual ring elements, by index. */ +#define RING_GET_REQUEST(_r, _idx) \ + (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) + +/* + * Get a local copy of a request. + * + * Use this in preference to RING_GET_REQUEST() so all processing is + * done on a local copy that cannot be modified by the other end. + * + * Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this + * to be ineffective where _req is a struct which consists of only bitfields. + */ +#define RING_COPY_REQUEST(_r, _idx, _req) do { \ + /* Use volatile to force the copy into _req. */ \ + *(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx); \ +} while (0) + +#define RING_GET_RESPONSE(_r, _idx) \ + (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp)) + +/* Loop termination condition: Would the specified index overflow the ring? */ +#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \ + (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r)) + +/* Ill-behaved frontend determination: Can there be this many requests? */ +#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \ + (((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r)) + +#define RING_PUSH_REQUESTS(_r) do { \ + xen_wmb(); /* back sees requests /before/ updated producer index */ \ + (_r)->sring->req_prod = (_r)->req_prod_pvt; \ +} while (0) + +#define RING_PUSH_RESPONSES(_r) do { \ + xen_wmb(); /* front sees resps /before/ updated producer index */ \ + (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ +} while (0) + +/* + * Notification hold-off (req_event and rsp_event): + * + * When queueing requests or responses on a shared ring, it may not always be + * necessary to notify the remote end. For example, if requests are in flight + * in a backend, the front may be able to queue further requests without + * notifying the back (if the back checks for new requests when it queues + * responses). + * + * When enqueuing requests or responses: + * + * Use RING_PUSH_{REQUESTS,RESPONSES}_AND_CHECK_NOTIFY(). The second argument + * is a boolean return value. True indicates that the receiver requires an + * asynchronous notification. + * + * After dequeuing requests or responses (before sleeping the connection): + * + * Use RING_FINAL_CHECK_FOR_REQUESTS() or RING_FINAL_CHECK_FOR_RESPONSES(). + * The second argument is a boolean return value. True indicates that there + * are pending messages on the ring (i.e., the connection should not be put + * to sleep). + * + * These macros will set the req_event/rsp_event field to trigger a + * notification on the very next message that is enqueued. If you want to + * create batches of work (i.e., only receive a notification after several + * messages have been enqueued) then you will need to create a customised + * version of the FINAL_CHECK macro in your own code, which sets the event + * field appropriately. + */ + +#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ + RING_IDX __old = (_r)->sring->req_prod; \ + RING_IDX __new = (_r)->req_prod_pvt; \ + xen_wmb(); /* back sees requests /before/ updated producer index */ \ + (_r)->sring->req_prod = __new; \ + xen_mb(); /* back sees new requests /before/ we check req_event */ \ + (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ + (RING_IDX)(__new - __old)); \ +} while (0) + +#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ + RING_IDX __old = (_r)->sring->rsp_prod; \ + RING_IDX __new = (_r)->rsp_prod_pvt; \ + xen_wmb(); /* front sees resps /before/ updated producer index */ \ + (_r)->sring->rsp_prod = __new; \ + xen_mb(); /* front sees new resps /before/ we check rsp_event */ \ + (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ + (RING_IDX)(__new - __old)); \ +} while (0) + +#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \ + (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ + if (_work_to_do) break; \ + (_r)->sring->req_event = (_r)->req_cons + 1; \ + xen_mb(); \ + (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ +} while (0) + +#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \ + (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ + if (_work_to_do) break; \ + (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ + xen_mb(); \ + (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ +} while (0) + + +/* + * DEFINE_XEN_FLEX_RING_AND_INTF defines two monodirectional rings and + * functions to check if there is data on the ring, and to read and + * write to them. + * + * DEFINE_XEN_FLEX_RING is similar to DEFINE_XEN_FLEX_RING_AND_INTF, but + * does not define the indexes page. As different protocols can have + * extensions to the basic format, this macro allow them to define their + * own struct. + * + * XEN_FLEX_RING_SIZE + * Convenience macro to calculate the size of one of the two rings + * from the overall order. + * + * $NAME_mask + * Function to apply the size mask to an index, to reduce the index + * within the range [0-size]. + * + * $NAME_read_packet + * Function to read data from the ring. The amount of data to read is + * specified by the "size" argument. + * + * $NAME_write_packet + * Function to write data to the ring. The amount of data to write is + * specified by the "size" argument. + * + * $NAME_get_ring_ptr + * Convenience function that returns a pointer to read/write to the + * ring at the right location. + * + * $NAME_data_intf + * Indexes page, shared between frontend and backend. It also + * contains the array of grant refs. + * + * $NAME_queued + * Function to calculate how many bytes are currently on the ring, + * ready to be read. It can also be used to calculate how much free + * space is currently on the ring (ring_size - $NAME_queued()). + */ +#define XEN_FLEX_RING_SIZE(order) \ + (1UL << (order + PAGE_SHIFT - 1)) + +#define DEFINE_XEN_FLEX_RING_AND_INTF(name) \ +struct name##_data_intf { \ + RING_IDX in_cons, in_prod; \ + \ + uint8_t pad1[56]; \ + \ + RING_IDX out_cons, out_prod; \ + \ + uint8_t pad2[56]; \ + \ + RING_IDX ring_order; \ + grant_ref_t ref[]; \ +}; \ +DEFINE_XEN_FLEX_RING(name); + +#define DEFINE_XEN_FLEX_RING(name) \ +static inline RING_IDX name##_mask(RING_IDX idx, RING_IDX ring_size) \ +{ \ + return (idx & (ring_size - 1)); \ +} \ + \ +static inline RING_IDX name##_mask_order(RING_IDX idx, RING_IDX ring_order) \ +{ \ + return (idx & (XEN_FLEX_RING_SIZE(ring_order) - 1)); \ +} \ + \ +static inline unsigned char* name##_get_ring_ptr(unsigned char *buf, \ + RING_IDX idx, \ + RING_IDX ring_order) \ +{ \ + return buf + name##_mask_order(idx, ring_order); \ +} \ + \ +static inline void name##_read_packet(const unsigned char *buf, \ + RING_IDX masked_prod, RING_IDX *masked_cons, \ + RING_IDX ring_size, void *opaque, size_t size) { \ + if (*masked_cons < masked_prod || \ + size <= ring_size - *masked_cons) { \ + memcpy(opaque, buf + *masked_cons, size); \ + } else { \ + memcpy(opaque, buf + *masked_cons, ring_size - *masked_cons); \ + memcpy((unsigned char *)opaque + ring_size - *masked_cons, buf, \ + size - (ring_size - *masked_cons)); \ + } \ + *masked_cons = name##_mask(*masked_cons + size, ring_size); \ +} \ + \ +static inline void name##_write_packet(unsigned char *buf, \ + RING_IDX *masked_prod, RING_IDX masked_cons, \ + RING_IDX ring_size, const void *opaque, size_t size) { \ + if (*masked_prod < masked_cons || \ + size <= ring_size - *masked_prod) { \ + memcpy(buf + *masked_prod, opaque, size); \ + } else { \ + memcpy(buf + *masked_prod, opaque, ring_size - *masked_prod); \ + memcpy(buf, (unsigned char *)opaque + (ring_size - *masked_prod), \ + size - (ring_size - *masked_prod)); \ + } \ + *masked_prod = name##_mask(*masked_prod + size, ring_size); \ +} \ + \ +struct name##_data { \ + unsigned char *in; /* half of the allocation */ \ + unsigned char *out; /* half of the allocation */ \ +}; \ + \ + \ +static inline RING_IDX name##_queued(RING_IDX prod, \ + RING_IDX cons, RING_IDX ring_size) \ +{ \ + RING_IDX size; \ + \ + if (prod == cons) \ + return 0; \ + \ + prod = name##_mask(prod, ring_size); \ + cons = name##_mask(cons, ring_size); \ + \ + if (prod == cons) \ + return ring_size; \ + \ + if (prod > cons) \ + size = prod - cons; \ + else \ + size = ring_size - (cons - prod); \ + return size; \ +}; + +#endif /* __XEN_PUBLIC_IO_RING_H__ */ + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */
Do not use the ring.h header installed on the system. Instead, import the header into the QEMU codebase. This avoids problems when QEMU is built against a Xen version too old to provide all the ring macros. Signed-off-by: Stefano Stabellini <stefano@aporeto.com> CC: anthony.perard@citrix.com CC: jgross@suse.com --- NB: The new macros have not been committed to Xen yet. Do not apply this patch until they do. --- --- hw/block/xen_blkif.h | 2 +- hw/usb/xen-usb.c | 2 +- include/hw/xen/io/ring.h | 455 +++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 457 insertions(+), 2 deletions(-) create mode 100644 include/hw/xen/io/ring.h