diff mbox series

[v5,4/5] common/domain: add a domain context record for shared_info...

Message ID 20200521161939.4508-5-paul@xen.org (mailing list archive)
State Superseded
Headers show
Series domain context infrastructure | expand

Commit Message

Paul Durrant May 21, 2020, 4:19 p.m. UTC 
From: Paul Durrant <pdurrant@amazon.com>

... and update xen-domctx to dump some information describing the record.

NOTE: The domain may or may not be using the embedded vcpu_info array so
      ultimately separate context records will be added for vcpu_info when
      this becomes necessary.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Wei Liu <wl@xen.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <george.dunlap@citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Julien Grall <julien@xen.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>

v5:
 - Addressed comments from Julien

v4:
 - Addressed comments from Jan

v3:
 - Actually dump some of the content of shared_info

v2:
 - Drop the header change to define a 'Xen' page size and instead use a
   variable length struct now that the framework makes this is feasible
 - Guard use of 'has_32bit_shinfo' in common code with CONFIG_COMPAT
---
 tools/misc/xen-domctx.c   | 78 +++++++++++++++++++++++++++++++++++++++
 xen/common/domain.c       | 65 ++++++++++++++++++++++++++++++++
 xen/include/public/save.h | 13 ++++++-
 3 files changed, 155 insertions(+), 1 deletion(-)

Comments

Jan Beulich May 22, 2020, 2:34 p.m. UTC | #1 
On 21.05.2020 18:19, Paul Durrant wrote:
> @@ -1649,6 +1650,70 @@ int continue_hypercall_on_cpu(
>      return 0;
>  }
>  
> +static int save_shared_info(const struct domain *d, struct domain_context *c,
> +                            bool dry_run)
> +{
> +    struct domain_shared_info_context ctxt = {
> +#ifdef CONFIG_COMPAT
> +        .flags = has_32bit_shinfo(d) ? DOMAIN_SAVE_32BIT_SHINFO : 0,
> +#endif
> +        .buffer_size = sizeof(shared_info_t),

But this size varies between native and compat.

> +static int load_shared_info(struct domain *d, struct domain_context *c)
> +{
> +    struct domain_shared_info_context ctxt;
> +    size_t hdr_size = offsetof(typeof(ctxt), buffer);
> +    unsigned int i;
> +    int rc;
> +
> +    rc = DOMAIN_LOAD_BEGIN(SHARED_INFO, c, &i);
> +    if ( rc )
> +        return rc;
> +
> +    if ( i ) /* expect only a single instance */
> +        return -ENXIO;
> +
> +    rc = domain_load_data(c, &ctxt, hdr_size);
> +    if ( rc )
> +        return rc;
> +
> +    if ( ctxt.buffer_size != sizeof(shared_info_t) )
> +        return -EINVAL;

While on the save side things could be left as they are (yet
I'd prefer a change), this should be flexible enough to allow
at least the smaller compat size as well in the compat case.
I wonder whether any smaller sizes might be acceptable, once
again with the rest getting zero-padded.

> +    if ( ctxt.flags & DOMAIN_SAVE_32BIT_SHINFO )
> +#ifdef CONFIG_COMPAT
> +        has_32bit_shinfo(d) = true;
> +#else
> +        return -EINVAL;
> +#endif

Am I mis-remembering or was a check lost of the remaining
flags being zero? If I am, one needs adding in any case, imo.

Jan
Durrant, Paul May 22, 2020, 2:45 p.m. UTC | #2 
> -----Original Message-----
> From: Jan Beulich <jbeulich@suse.com>
> Sent: 22 May 2020 15:34
> To: Paul Durrant <paul@xen.org>
> Cc: xen-devel@lists.xenproject.org; Durrant, Paul <pdurrant@amazon.co.uk>; Ian Jackson
> <ian.jackson@eu.citrix.com>; Wei Liu <wl@xen.org>; Andrew Cooper <andrew.cooper3@citrix.com>; George
> Dunlap <george.dunlap@citrix.com>; Julien Grall <julien@xen.org>; Stefano Stabellini
> <sstabellini@kernel.org>
> Subject: RE: [EXTERNAL] [PATCH v5 4/5] common/domain: add a domain context record for shared_info...
> 
> CAUTION: This email originated from outside of the organization. Do not click links or open
> attachments unless you can confirm the sender and know the content is safe.
> 
> 
> 
> On 21.05.2020 18:19, Paul Durrant wrote:
> > @@ -1649,6 +1650,70 @@ int continue_hypercall_on_cpu(
> >      return 0;
> >  }
> >
> > +static int save_shared_info(const struct domain *d, struct domain_context *c,
> > +                            bool dry_run)
> > +{
> > +    struct domain_shared_info_context ctxt = {
> > +#ifdef CONFIG_COMPAT
> > +        .flags = has_32bit_shinfo(d) ? DOMAIN_SAVE_32BIT_SHINFO : 0,
> > +#endif
> > +        .buffer_size = sizeof(shared_info_t),
> 
> But this size varies between native and compat.
> 
> > +static int load_shared_info(struct domain *d, struct domain_context *c)
> > +{
> > +    struct domain_shared_info_context ctxt;
> > +    size_t hdr_size = offsetof(typeof(ctxt), buffer);
> > +    unsigned int i;
> > +    int rc;
> > +
> > +    rc = DOMAIN_LOAD_BEGIN(SHARED_INFO, c, &i);
> > +    if ( rc )
> > +        return rc;
> > +
> > +    if ( i ) /* expect only a single instance */
> > +        return -ENXIO;
> > +
> > +    rc = domain_load_data(c, &ctxt, hdr_size);
> > +    if ( rc )
> > +        return rc;
> > +
> > +    if ( ctxt.buffer_size != sizeof(shared_info_t) )
> > +        return -EINVAL;
> 
> While on the save side things could be left as they are (yet
> I'd prefer a change), this should be flexible enough to allow
> at least the smaller compat size as well in the compat case.

Ok, I guess we can optimize the buffer size down if only the compat version is needed. Seems like slightly pointless complexity though.

> I wonder whether any smaller sizes might be acceptable, once
> again with the rest getting zero-padded.
> 

If the need arises to zero extend an older shared_info variant then that can be done in future.

> > +    if ( ctxt.flags & DOMAIN_SAVE_32BIT_SHINFO )
> > +#ifdef CONFIG_COMPAT
> > +        has_32bit_shinfo(d) = true;
> > +#else
> > +        return -EINVAL;
> > +#endif
> 
> Am I mis-remembering or was a check lost of the remaining
> flags being zero? If I am, one needs adding in any case, imo.
> 

It wasn't flags before, but you're quite right; they should be zero-checked.

  Paul

> Jan
diff mbox series

Patch

diff --git a/tools/misc/xen-domctx.c b/tools/misc/xen-domctx.c
index 243325dfce..6ead7ea89d 100644
--- a/tools/misc/xen-domctx.c
+++ b/tools/misc/xen-domctx.c
@@ -31,6 +31,7 @@ 
 #include <errno.h>
 
 #include <xenctrl.h>
+#include <xen-tools/libs.h>
 #include <xen/xen.h>
 #include <xen/domctl.h>
 #include <xen/save.h>
@@ -61,6 +62,82 @@  static void dump_header(void)
 
 }
 
+static void print_binary(const char *prefix, const void *val, size_t size,
+                         const char *suffix)
+{
+    printf("%s", prefix);
+
+    while ( size-- )
+    {
+        uint8_t octet = *(const uint8_t *)val++;
+        unsigned int i;
+
+        for ( i = 0; i < 8; i++ )
+        {
+            printf("%u", octet & 1);
+            octet >>= 1;
+        }
+    }
+
+    printf("%s", suffix);
+}
+
+static void dump_shared_info(void)
+{
+    DOMAIN_SAVE_TYPE(SHARED_INFO) *s;
+    bool has_32bit_shinfo;
+    shared_info_any_t *info;
+    unsigned int i, n;
+
+    GET_PTR(s);
+    has_32bit_shinfo = s->flags & DOMAIN_SAVE_32BIT_SHINFO;
+
+    printf("    SHARED_INFO: has_32bit_shinfo: %s buffer_size: %u\n",
+           has_32bit_shinfo ? "true" : "false", s->buffer_size);
+
+    info = (shared_info_any_t *)s->buffer;
+
+#define GET_FIELD_PTR(_f)            \
+    (has_32bit_shinfo ?              \
+     (const void *)&(info->x32._f) : \
+     (const void *)&(info->x64._f))
+#define GET_FIELD_SIZE(_f) \
+    (has_32bit_shinfo ? sizeof(info->x32._f) : sizeof(info->x64._f))
+#define GET_FIELD(_f) \
+    (has_32bit_shinfo ? info->x32._f : info->x64._f)
+
+    n = has_32bit_shinfo ?
+        ARRAY_SIZE(info->x32.evtchn_pending) :
+        ARRAY_SIZE(info->x64.evtchn_pending);
+
+    for ( i = 0; i < n; i++ )
+    {
+        const char *prefix = !i ?
+            "                 evtchn_pending: " :
+            "                                 ";
+
+        print_binary(prefix, GET_FIELD_PTR(evtchn_pending[0]),
+                 GET_FIELD_SIZE(evtchn_pending[0]), "\n");
+    }
+
+    for ( i = 0; i < n; i++ )
+    {
+        const char *prefix = !i ?
+            "                    evtchn_mask: " :
+            "                                 ";
+
+        print_binary(prefix, GET_FIELD_PTR(evtchn_mask[0]),
+                 GET_FIELD_SIZE(evtchn_mask[0]), "\n");
+    }
+
+    printf("                 wc: version: %u sec: %u nsec: %u\n",
+           GET_FIELD(wc_version), GET_FIELD(wc_sec), GET_FIELD(wc_nsec));
+
+#undef GET_FIELD
+#undef GET_FIELD_SIZE
+#undef GET_FIELD_PTR
+}
+
 static void dump_end(void)
 {
     DOMAIN_SAVE_TYPE(END) *e;
@@ -173,6 +250,7 @@  int main(int argc, char **argv)
             switch (desc->typecode)
             {
             case DOMAIN_SAVE_CODE(HEADER): dump_header(); break;
+            case DOMAIN_SAVE_CODE(SHARED_INFO): dump_shared_info(); break;
             case DOMAIN_SAVE_CODE(END): dump_end(); break;
             default:
                 printf("Unknown type %u: skipping\n", desc->typecode);
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 7cc9526139..9d156da84d 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -33,6 +33,7 @@ 
 #include <xen/xenoprof.h>
 #include <xen/irq.h>
 #include <xen/argo.h>
+#include <xen/save.h>
 #include <asm/debugger.h>
 #include <asm/p2m.h>
 #include <asm/processor.h>
@@ -1649,6 +1650,70 @@  int continue_hypercall_on_cpu(
     return 0;
 }
 
+static int save_shared_info(const struct domain *d, struct domain_context *c,
+                            bool dry_run)
+{
+    struct domain_shared_info_context ctxt = {
+#ifdef CONFIG_COMPAT
+        .flags = has_32bit_shinfo(d) ? DOMAIN_SAVE_32BIT_SHINFO : 0,
+#endif
+        .buffer_size = sizeof(shared_info_t),
+    };
+    size_t hdr_size = offsetof(typeof(ctxt), buffer);
+    int rc;
+
+    rc = DOMAIN_SAVE_BEGIN(SHARED_INFO, c, 0);
+    if ( rc )
+        return rc;
+
+    rc = domain_save_data(c, &ctxt, hdr_size);
+    if ( rc )
+        return rc;
+
+    rc = domain_save_data(c, d->shared_info, ctxt.buffer_size);
+    if ( rc )
+        return rc;
+
+    return domain_save_end(c);
+}
+
+static int load_shared_info(struct domain *d, struct domain_context *c)
+{
+    struct domain_shared_info_context ctxt;
+    size_t hdr_size = offsetof(typeof(ctxt), buffer);
+    unsigned int i;
+    int rc;
+
+    rc = DOMAIN_LOAD_BEGIN(SHARED_INFO, c, &i);
+    if ( rc )
+        return rc;
+
+    if ( i ) /* expect only a single instance */
+        return -ENXIO;
+
+    rc = domain_load_data(c, &ctxt, hdr_size);
+    if ( rc )
+        return rc;
+
+    if ( ctxt.buffer_size != sizeof(shared_info_t) )
+        return -EINVAL;
+
+    if ( ctxt.flags & DOMAIN_SAVE_32BIT_SHINFO )
+#ifdef CONFIG_COMPAT
+        has_32bit_shinfo(d) = true;
+#else
+        return -EINVAL;
+#endif
+
+    rc = domain_load_data(c, d->shared_info, sizeof(shared_info_t));
+    if ( rc )
+        return rc;
+
+    return domain_load_end(c);
+}
+
+DOMAIN_REGISTER_SAVE_LOAD(SHARED_INFO, save_shared_info, load_shared_info);
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/public/save.h b/xen/include/public/save.h
index 551dbbddb8..0e855a4b97 100644
--- a/xen/include/public/save.h
+++ b/xen/include/public/save.h
@@ -82,7 +82,18 @@  struct domain_save_header {
 };
 DECLARE_DOMAIN_SAVE_TYPE(HEADER, 1, struct domain_save_header);
 
-#define DOMAIN_SAVE_CODE_MAX 1
+struct domain_shared_info_context {
+    uint32_t flags;
+
+#define DOMAIN_SAVE_32BIT_SHINFO 0x00000001
+
+    uint32_t buffer_size;
+    uint8_t buffer[XEN_FLEX_ARRAY_DIM]; /* Implementation specific size */
+};
+
+DECLARE_DOMAIN_SAVE_TYPE(SHARED_INFO, 2, struct domain_shared_info_context);
+
+#define DOMAIN_SAVE_CODE_MAX 2
 
 #endif /* defined(__XEN__) || defined(__XEN_TOOLS__) */