[PATCH] libxl_pci: check that host device is assignable before adding to the domain

[Doug Magee <djmagee@mageenet.net>]

Previously, on ..._pci_add, libxl only checks that a device is not assigned to another domain. This quick patch checks that the device is also owned by pciback, otherwise the call fails.

Signed-off-by: Doug Magee <djmagee@mageenet.net>

diff -r 5b2676ac1321 -r 301cc006677f tools/libxl/libxl_pci.c
--- a/tools/libxl/libxl_pci.c	Mon Jan 09 16:01:44 2012 +0100
+++ b/tools/libxl/libxl_pci.c	Mon Jan 16 17:31:25 2012 -0500
@@ -796,6 +796,9 @@ int libxl__device_pci_add(libxl__gc *gc,
     libxl_device_pci *assigned;
     int num_assigned, i, rc;
     int stubdomid = 0;
+    struct dirent *de;
+    DIR *dir;
+    int assignable = 0;
 
     rc = get_all_assigned_devices(gc, &assigned, &num_assigned);
     if ( rc ) {
@@ -809,6 +812,35 @@ int libxl__device_pci_add(libxl__gc *gc,
         goto out;
     }
 
+    dir = opendir(SYSFS_PCIBACK_DRIVER);
+    if ( NULL == dir ) {
+        if ( errno == ENOENT ) {
+            LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "Looks like pciback driver not loaded");
+        }else{
+            LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "Couldn't open %s", SYSFS_PCIBACK_DRIVER);
+        }
+        rc = ERROR_FAIL;
+        goto out_closedir;
+    }
+
+    while( (de = readdir(dir)) ) {
+        unsigned dom, bus, dev, func;
+        if ( sscanf(de->d_name, PCI_BDF, &dom, &bus, &dev, &func) != 4 )
+            continue;
+        if ( dom == pcidev->domain && bus == pcidev->bus &&
+              dev == pcidev->dev && func == pcidev->func ) {
+            assignable = 1;
+            break;
+        }
+    }
+
+    if ( !assignable ) {
+        rc = ERROR_FAIL;
+        LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "PCI device not owned by pciback");
+        goto out_closedir;
+    }
+
+
     libxl__device_pci_reset(gc, pcidev->domain, pcidev->bus, pcidev->dev, pcidev->func);
 
     stubdomid = libxl_get_stubdom_id(ctx, domid);
@@ -817,7 +849,7 @@ int libxl__device_pci_add(libxl__gc *gc,
         /* stubdomain is always running by now, even at create time */
         rc = do_pci_add(gc, stubdomid, &pcidev_s, 0);
         if ( rc )
-            goto out;
+            goto out_closedir;
     }
 
     orig_vdev = pcidev->vdevfn & ~7U;
@@ -826,11 +858,11 @@ int libxl__device_pci_add(libxl__gc *gc,
         if ( !(pcidev->vdevfn >> 3) ) {
             LIBXL__LOG(ctx, LIBXL__LOG_ERROR, "Must specify a v-slot for multi-function devices");
             rc = ERROR_INVAL;
-            goto out;
+            goto out_closedir;
         }
         if ( pci_multifunction_check(gc, pcidev, &pfunc_mask) ) {
             rc = ERROR_FAIL;
-            goto out;
+            goto out_closedir;
         }
         pcidev->vfunc_mask &= pfunc_mask;
         /* so now vfunc_mask == pfunc_mask */
@@ -855,6 +887,8 @@ int libxl__device_pci_add(libxl__gc *gc,
         }
     }
 
+out_closedir:
+    closedir(dir);
 out:
     return rc;
 }