diff mbox series

[v4,10/23] libxl: remove get_all_assigned_devices() from libxl_pci.c

Message ID 20201124080159.11912-11-paul@xen.org (mailing list archive)
State Superseded
Headers show
Series xl / libxl: named PCI pass-through devices | expand

Commit Message

Paul Durrant Nov. 24, 2020, 8:01 a.m. UTC 
From: Paul Durrant <pdurrant@amazon.com>

Use of this function is a very inefficient way to check whether a device
has already been assigned.

This patch adds code that saves the domain id in xenstore at the point of
assignment, and removes it again when the device id de-assigned (or the
domain is destroyed). It is then straightforward to check whether a device
has been assigned by checking whether a device has a saved domain id.

NOTE: To facilitate the xenstore check it is necessary to move the
      pci_info_xs_read() earlier in libxl_pci.c. To keep related functions
      together, the rest of the pci_info_xs_XXX() functions are moved too.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Ian Jackson <iwj@xenproject.org>
Cc: Wei Liu <wl@xen.org>
---
 tools/libs/light/libxl_pci.c | 149 ++++++++++++++++---------------------------
 1 file changed, 55 insertions(+), 94 deletions(-)

Comments

Oleksandr Andrushchenko Dec. 1, 2020, 2:18 p.m. UTC | #1 
Hi, Paul!

On 11/24/20 10:01 AM, Paul Durrant wrote:
> From: Paul Durrant <pdurrant@amazon.com>
>
> Use of this function is a very inefficient way to check whether a device
> has already been assigned.
>
> This patch adds code that saves the domain id in xenstore at the point of
> assignment, and removes it again when the device id de-assigned (or the
> domain is destroyed). It is then straightforward to check whether a device
> has been assigned by checking whether a device has a saved domain id.
>
> NOTE: To facilitate the xenstore check it is necessary to move the
>        pci_info_xs_read() earlier in libxl_pci.c. To keep related functions
>        together, the rest of the pci_info_xs_XXX() functions are moved too.
>
> Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Thank you,

Oleksandr

> ---
> Cc: Ian Jackson <iwj@xenproject.org>
> Cc: Wei Liu <wl@xen.org>
> ---
>   tools/libs/light/libxl_pci.c | 149 ++++++++++++++++---------------------------
>   1 file changed, 55 insertions(+), 94 deletions(-)
>
> diff --git a/tools/libs/light/libxl_pci.c b/tools/libs/light/libxl_pci.c
> index ec101f255f..d3c7a547c3 100644
> --- a/tools/libs/light/libxl_pci.c
> +++ b/tools/libs/light/libxl_pci.c
> @@ -336,50 +336,6 @@ retry_transaction2:
>       return 0;
>   }
>   
> -static int get_all_assigned_devices(libxl__gc *gc, libxl_device_pci **list, int *num)
> -{
> -    char **domlist;
> -    unsigned int nd = 0, i;
> -
> -    *list = NULL;
> -    *num = 0;
> -
> -    domlist = libxl__xs_directory(gc, XBT_NULL, "/local/domain", &nd);
> -    for(i = 0; i < nd; i++) {
> -        char *path, *num_devs;
> -
> -        path = GCSPRINTF("/local/domain/0/backend/%s/%s/0/num_devs",
> -                         libxl__device_kind_to_string(LIBXL__DEVICE_KIND_PCI),
> -                         domlist[i]);
> -        num_devs = libxl__xs_read(gc, XBT_NULL, path);
> -        if ( num_devs ) {
> -            int ndev = atoi(num_devs), j;
> -            char *devpath, *bdf;
> -
> -            for(j = 0; j < ndev; j++) {
> -                devpath = GCSPRINTF("/local/domain/0/backend/%s/%s/0/dev-%u",
> -                                    libxl__device_kind_to_string(LIBXL__DEVICE_KIND_PCI),
> -                                    domlist[i], j);
> -                bdf = libxl__xs_read(gc, XBT_NULL, devpath);
> -                if ( bdf ) {
> -                    unsigned dom, bus, dev, func;
> -                    if ( sscanf(bdf, PCI_BDF, &dom, &bus, &dev, &func) != 4 )
> -                        continue;
> -
> -                    *list = realloc(*list, sizeof(libxl_device_pci) * ((*num) + 1));
> -                    if (*list == NULL)
> -                        return ERROR_NOMEM;
> -                    pci_struct_fill(*list + *num, dom, bus, dev, func, 0);
> -                    (*num)++;
> -                }
> -            }
> -        }
> -    }
> -    libxl__ptr_add(gc, *list);
> -
> -    return 0;
> -}
> -
>   static int is_pci_in_array(libxl_device_pci *assigned, int num_assigned,
>                              int dom, int bus, int dev, int func)
>   {
> @@ -427,19 +383,58 @@ static int sysfs_write_bdf(libxl__gc *gc, const char * sysfs_path,
>       return 0;
>   }
>   
> +#define PCI_INFO_PATH "/libxl/pci"
> +
> +static char *pci_info_xs_path(libxl__gc *gc, libxl_device_pci *pci,
> +                              const char *node)
> +{
> +    return node ?
> +        GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH"/%s",
> +                  pci->domain, pci->bus, pci->dev, pci->func,
> +                  node) :
> +        GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH,
> +                  pci->domain, pci->bus, pci->dev, pci->func);
> +}
> +
> +
> +static int pci_info_xs_write(libxl__gc *gc, libxl_device_pci *pci,
> +                              const char *node, const char *val)
> +{
> +    char *path = pci_info_xs_path(gc, pci, node);
> +    int rc = libxl__xs_printf(gc, XBT_NULL, path, "%s", val);
> +
> +    if (rc) LOGE(WARN, "Write of %s to node %s failed.", val, path);
> +
> +    return rc;
> +}
> +
> +static char *pci_info_xs_read(libxl__gc *gc, libxl_device_pci *pci,
> +                              const char *node)
> +{
> +    char *path = pci_info_xs_path(gc, pci, node);
> +
> +    return libxl__xs_read(gc, XBT_NULL, path);
> +}
> +
> +static void pci_info_xs_remove(libxl__gc *gc, libxl_device_pci *pci,
> +                               const char *node)
> +{
> +    char *path = pci_info_xs_path(gc, pci, node);
> +    libxl_ctx *ctx = libxl__gc_owner(gc);
> +
> +    /* Remove the xenstore entry */
> +    xs_rm(ctx->xsh, XBT_NULL, path);
> +}
> +
>   libxl_device_pci *libxl_device_pci_assignable_list(libxl_ctx *ctx, int *num)
>   {
>       GC_INIT(ctx);
> -    libxl_device_pci *pcis = NULL, *new, *assigned;
> +    libxl_device_pci *pcis = NULL, *new;
>       struct dirent *de;
>       DIR *dir;
> -    int r, num_assigned;
>   
>       *num = 0;
>   
> -    r = get_all_assigned_devices(gc, &assigned, &num_assigned);
> -    if (r) goto out;
> -
>       dir = opendir(SYSFS_PCIBACK_DRIVER);
>       if (NULL == dir) {
>           if (errno == ENOENT) {
> @@ -455,9 +450,6 @@ libxl_device_pci *libxl_device_pci_assignable_list(libxl_ctx *ctx, int *num)
>           if (sscanf(de->d_name, PCI_BDF, &dom, &bus, &dev, &func) != 4)
>               continue;
>   
> -        if (is_pci_in_array(assigned, num_assigned, dom, bus, dev, func))
> -            continue;
> -
>           new = realloc(pcis, ((*num) + 1) * sizeof(*new));
>           if (NULL == new)
>               continue;
> @@ -467,6 +459,10 @@ libxl_device_pci *libxl_device_pci_assignable_list(libxl_ctx *ctx, int *num)
>   
>           memset(new, 0, sizeof(*new));
>           pci_struct_fill(new, dom, bus, dev, func, 0);
> +
> +        if (pci_info_xs_read(gc, new, "domid")) /* already assigned */
> +            continue;
> +
>           (*num)++;
>       }
>   
> @@ -737,48 +733,6 @@ static int pciback_dev_unassign(libxl__gc *gc, libxl_device_pci *pci)
>       return 0;
>   }
>   
> -#define PCI_INFO_PATH "/libxl/pci"
> -
> -static char *pci_info_xs_path(libxl__gc *gc, libxl_device_pci *pci,
> -                              const char *node)
> -{
> -    return node ?
> -        GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH"/%s",
> -                  pci->domain, pci->bus, pci->dev, pci->func,
> -                  node) :
> -        GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH,
> -                  pci->domain, pci->bus, pci->dev, pci->func);
> -}
> -
> -
> -static void pci_info_xs_write(libxl__gc *gc, libxl_device_pci *pci,
> -                              const char *node, const char *val)
> -{
> -    char *path = pci_info_xs_path(gc, pci, node);
> -
> -    if ( libxl__xs_printf(gc, XBT_NULL, path, "%s", val) < 0 ) {
> -        LOGE(WARN, "Write of %s to node %s failed.", val, path);
> -    }
> -}
> -
> -static char *pci_info_xs_read(libxl__gc *gc, libxl_device_pci *pci,
> -                              const char *node)
> -{
> -    char *path = pci_info_xs_path(gc, pci, node);
> -
> -    return libxl__xs_read(gc, XBT_NULL, path);
> -}
> -
> -static void pci_info_xs_remove(libxl__gc *gc, libxl_device_pci *pci,
> -                               const char *node)
> -{
> -    char *path = pci_info_xs_path(gc, pci, node);
> -    libxl_ctx *ctx = libxl__gc_owner(gc);
> -
> -    /* Remove the xenstore entry */
> -    xs_rm(ctx->xsh, XBT_NULL, path);
> -}
> -
>   static int libxl__device_pci_assignable_add(libxl__gc *gc,
>                                               libxl_device_pci *pci,
>                                               int rebind)
> @@ -1594,6 +1548,9 @@ void libxl__device_pci_add(libxl__egc *egc, uint32_t domid,
>           goto out;
>       }
>   
> +    rc = pci_info_xs_write(gc, pci, "domid", GCSPRINTF("%u", domid));
> +    if (rc) goto out;
> +
>       libxl__device_pci_reset(gc, pci->domain, pci->bus, pci->dev, pci->func);
>   
>       stubdomid = libxl_get_stubdom_id(ctx, domid);
> @@ -1721,6 +1678,7 @@ static void device_pci_add_done(libxl__egc *egc,
>                "PCI device %x:%x:%x.%x (rc %d)",
>                pci->domain, pci->bus, pci->dev, pci->func,
>                rc);
> +        pci_info_xs_remove(gc, pci, "domid");
>       }
>       aodev->rc = rc;
>       aodev->callback(egc, aodev);
> @@ -2282,6 +2240,9 @@ out:
>       libxl__xswait_stop(gc, &prs->xswait);
>       libxl__ev_time_deregister(gc, &prs->timeout);
>       libxl__ev_time_deregister(gc, &prs->retry_timer);
> +
> +    if (!rc) pci_info_xs_remove(gc, pci, "domid");
> +
>       aodev->rc = rc;
>       aodev->callback(egc, aodev);
>   }
diff mbox series

Patch

diff --git a/tools/libs/light/libxl_pci.c b/tools/libs/light/libxl_pci.c
index ec101f255f..d3c7a547c3 100644
--- a/tools/libs/light/libxl_pci.c
+++ b/tools/libs/light/libxl_pci.c
@@ -336,50 +336,6 @@  retry_transaction2:
     return 0;
 }
 
-static int get_all_assigned_devices(libxl__gc *gc, libxl_device_pci **list, int *num)
-{
-    char **domlist;
-    unsigned int nd = 0, i;
-
-    *list = NULL;
-    *num = 0;
-
-    domlist = libxl__xs_directory(gc, XBT_NULL, "/local/domain", &nd);
-    for(i = 0; i < nd; i++) {
-        char *path, *num_devs;
-
-        path = GCSPRINTF("/local/domain/0/backend/%s/%s/0/num_devs",
-                         libxl__device_kind_to_string(LIBXL__DEVICE_KIND_PCI),
-                         domlist[i]);
-        num_devs = libxl__xs_read(gc, XBT_NULL, path);
-        if ( num_devs ) {
-            int ndev = atoi(num_devs), j;
-            char *devpath, *bdf;
-
-            for(j = 0; j < ndev; j++) {
-                devpath = GCSPRINTF("/local/domain/0/backend/%s/%s/0/dev-%u",
-                                    libxl__device_kind_to_string(LIBXL__DEVICE_KIND_PCI),
-                                    domlist[i], j);
-                bdf = libxl__xs_read(gc, XBT_NULL, devpath);
-                if ( bdf ) {
-                    unsigned dom, bus, dev, func;
-                    if ( sscanf(bdf, PCI_BDF, &dom, &bus, &dev, &func) != 4 )
-                        continue;
-
-                    *list = realloc(*list, sizeof(libxl_device_pci) * ((*num) + 1));
-                    if (*list == NULL)
-                        return ERROR_NOMEM;
-                    pci_struct_fill(*list + *num, dom, bus, dev, func, 0);
-                    (*num)++;
-                }
-            }
-        }
-    }
-    libxl__ptr_add(gc, *list);
-
-    return 0;
-}
-
 static int is_pci_in_array(libxl_device_pci *assigned, int num_assigned,
                            int dom, int bus, int dev, int func)
 {
@@ -427,19 +383,58 @@  static int sysfs_write_bdf(libxl__gc *gc, const char * sysfs_path,
     return 0;
 }
 
+#define PCI_INFO_PATH "/libxl/pci"
+
+static char *pci_info_xs_path(libxl__gc *gc, libxl_device_pci *pci,
+                              const char *node)
+{
+    return node ?
+        GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH"/%s",
+                  pci->domain, pci->bus, pci->dev, pci->func,
+                  node) :
+        GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH,
+                  pci->domain, pci->bus, pci->dev, pci->func);
+}
+
+
+static int pci_info_xs_write(libxl__gc *gc, libxl_device_pci *pci,
+                              const char *node, const char *val)
+{
+    char *path = pci_info_xs_path(gc, pci, node);
+    int rc = libxl__xs_printf(gc, XBT_NULL, path, "%s", val);
+
+    if (rc) LOGE(WARN, "Write of %s to node %s failed.", val, path);
+
+    return rc;
+}
+
+static char *pci_info_xs_read(libxl__gc *gc, libxl_device_pci *pci,
+                              const char *node)
+{
+    char *path = pci_info_xs_path(gc, pci, node);
+
+    return libxl__xs_read(gc, XBT_NULL, path);
+}
+
+static void pci_info_xs_remove(libxl__gc *gc, libxl_device_pci *pci,
+                               const char *node)
+{
+    char *path = pci_info_xs_path(gc, pci, node);
+    libxl_ctx *ctx = libxl__gc_owner(gc);
+
+    /* Remove the xenstore entry */
+    xs_rm(ctx->xsh, XBT_NULL, path);
+}
+
 libxl_device_pci *libxl_device_pci_assignable_list(libxl_ctx *ctx, int *num)
 {
     GC_INIT(ctx);
-    libxl_device_pci *pcis = NULL, *new, *assigned;
+    libxl_device_pci *pcis = NULL, *new;
     struct dirent *de;
     DIR *dir;
-    int r, num_assigned;
 
     *num = 0;
 
-    r = get_all_assigned_devices(gc, &assigned, &num_assigned);
-    if (r) goto out;
-
     dir = opendir(SYSFS_PCIBACK_DRIVER);
     if (NULL == dir) {
         if (errno == ENOENT) {
@@ -455,9 +450,6 @@  libxl_device_pci *libxl_device_pci_assignable_list(libxl_ctx *ctx, int *num)
         if (sscanf(de->d_name, PCI_BDF, &dom, &bus, &dev, &func) != 4)
             continue;
 
-        if (is_pci_in_array(assigned, num_assigned, dom, bus, dev, func))
-            continue;
-
         new = realloc(pcis, ((*num) + 1) * sizeof(*new));
         if (NULL == new)
             continue;
@@ -467,6 +459,10 @@  libxl_device_pci *libxl_device_pci_assignable_list(libxl_ctx *ctx, int *num)
 
         memset(new, 0, sizeof(*new));
         pci_struct_fill(new, dom, bus, dev, func, 0);
+
+        if (pci_info_xs_read(gc, new, "domid")) /* already assigned */
+            continue;
+
         (*num)++;
     }
 
@@ -737,48 +733,6 @@  static int pciback_dev_unassign(libxl__gc *gc, libxl_device_pci *pci)
     return 0;
 }
 
-#define PCI_INFO_PATH "/libxl/pci"
-
-static char *pci_info_xs_path(libxl__gc *gc, libxl_device_pci *pci,
-                              const char *node)
-{
-    return node ?
-        GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH"/%s",
-                  pci->domain, pci->bus, pci->dev, pci->func,
-                  node) :
-        GCSPRINTF(PCI_INFO_PATH"/"PCI_BDF_XSPATH,
-                  pci->domain, pci->bus, pci->dev, pci->func);
-}
-
-
-static void pci_info_xs_write(libxl__gc *gc, libxl_device_pci *pci,
-                              const char *node, const char *val)
-{
-    char *path = pci_info_xs_path(gc, pci, node);
-
-    if ( libxl__xs_printf(gc, XBT_NULL, path, "%s", val) < 0 ) {
-        LOGE(WARN, "Write of %s to node %s failed.", val, path);
-    }
-}
-
-static char *pci_info_xs_read(libxl__gc *gc, libxl_device_pci *pci,
-                              const char *node)
-{
-    char *path = pci_info_xs_path(gc, pci, node);
-
-    return libxl__xs_read(gc, XBT_NULL, path);
-}
-
-static void pci_info_xs_remove(libxl__gc *gc, libxl_device_pci *pci,
-                               const char *node)
-{
-    char *path = pci_info_xs_path(gc, pci, node);
-    libxl_ctx *ctx = libxl__gc_owner(gc);
-
-    /* Remove the xenstore entry */
-    xs_rm(ctx->xsh, XBT_NULL, path);
-}
-
 static int libxl__device_pci_assignable_add(libxl__gc *gc,
                                             libxl_device_pci *pci,
                                             int rebind)
@@ -1594,6 +1548,9 @@  void libxl__device_pci_add(libxl__egc *egc, uint32_t domid,
         goto out;
     }
 
+    rc = pci_info_xs_write(gc, pci, "domid", GCSPRINTF("%u", domid));
+    if (rc) goto out;
+
     libxl__device_pci_reset(gc, pci->domain, pci->bus, pci->dev, pci->func);
 
     stubdomid = libxl_get_stubdom_id(ctx, domid);
@@ -1721,6 +1678,7 @@  static void device_pci_add_done(libxl__egc *egc,
              "PCI device %x:%x:%x.%x (rc %d)",
              pci->domain, pci->bus, pci->dev, pci->func,
              rc);
+        pci_info_xs_remove(gc, pci, "domid");
     }
     aodev->rc = rc;
     aodev->callback(egc, aodev);
@@ -2282,6 +2240,9 @@  out:
     libxl__xswait_stop(gc, &prs->xswait);
     libxl__ev_time_deregister(gc, &prs->timeout);
     libxl__ev_time_deregister(gc, &prs->retry_timer);
+
+    if (!rc) pci_info_xs_remove(gc, pci, "domid");
+
     aodev->rc = rc;
     aodev->callback(egc, aodev);
 }