vfio: blacklist loading of unstable roms

Certain cards such as the Broadcom BCM57810 have rom quirks
that exhibit unstable system behavior duing device assignment. In
the particular case of 57810, rom execution hangs and if a FLR
follows, the device becomes inoperable until a power cycle. This
change blacklists loading of rom for such cards unless the user
specifies a romfile or rombar=1 on the cmd line

Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

hw/misc/vfio.c

@@ -209,6 +209,29 @@ typedef struct VFIOGroup {
     QLIST_ENTRY(VFIOGroup) container_next;
 } VFIOGroup;
 
+typedef struct VFIORomBlacklistEntry {
+    uint16_t vendor_id;
+    uint16_t device_id;
+} VFIORomBlacklistEntry;
+
+/*
+ * List of device ids/vendor ids for which to disable
+ * option rom loading. This avoids the guest hangs during rom
+ * execution as noticed with the BCM 57810 card for lack of a
+ * more better way to handle such issues.
+ * The  user can still override by specifying a romfile or
+ * rombar=1.
+ * Please see https://bugs.launchpad.net/qemu/+bug/1284874
+ * for an analysis of the 57810 card hang. When adding
+ * a new vendor id/device id combination below, please also add
+ * your card/environment details and information that could
+ * help in debugging to the bug tracking this issue
+ */
+static const VFIORomBlacklistEntry romblacklist[] = {
+    /* Broadcom BCM 57810 */
+    { 0x14e4, 0x168e }
+};
+
 #define MSIX_CAP_LENGTH 12
 
 static QLIST_HEAD(, VFIOContainer)
@@ -1197,13 +1220,43 @@ static const MemoryRegionOps vfio_rom_ops = {
     .endianness = DEVICE_LITTLE_ENDIAN,
 };
 
+static bool vfio_blacklist_opt_rom(VFIODevice *vdev)
+{
+    PCIDevice *pdev = &vdev->pdev;
+    uint16_t vendor_id, device_id;
+    int count = 0;
+
+    vendor_id = pci_get_word(pdev->config + PCI_VENDOR_ID);
+    device_id = pci_get_word(pdev->config + PCI_DEVICE_ID);
+
+    while (count < ARRAY_SIZE(romblacklist)) {
+        if (romblacklist[count].vendor_id == vendor_id &&
+            romblacklist[count].device_id == device_id) {
+                return true;
+        }
+        count++;
+    }
+
+    return false;
+}
+
 static void vfio_pci_size_rom(VFIODevice *vdev)
 {
     uint32_t orig, size = cpu_to_le32((uint32_t)PCI_ROM_ADDRESS_MASK);
     off_t offset = vdev->config_offset + PCI_ROM_ADDRESS;
+    DeviceState *dev = DEVICE(vdev);
     char name[32];
 
     if (vdev->pdev.romfile || !vdev->pdev.rom_bar) {
+        /* Since pci handles romfile, just print a message and return */
+        if (vfio_blacklist_opt_rom(vdev) && vdev->pdev.romfile) {
+            error_printf("Warning : Device at %04x:%02x:%02x.%x "
+                         "is known to cause system instability issues during "
+                         "option rom execution. "
+                         "Proceeding anyway since user specified romfile\n",
+                         vdev->host.domain, vdev->host.bus, vdev->host.slot,
+                         vdev->host.function);
+        }
         return;
     }
 
@@ -1227,6 +1280,26 @@ static void vfio_pci_size_rom(VFIODevice *vdev)
         return;
     }
 
+    if (vfio_blacklist_opt_rom(vdev)) {
+        if (dev->opts && qemu_opt_get(dev->opts, "rombar")) {
+            error_printf("Warning : Device at %04x:%02x:%02x.%x "
+                         "is known to cause system instability issues during "
+                         "option rom execution. "
+                         "Proceeding anyway since user specified non zero value for "
+                         "rombar\n",
+                         vdev->host.domain, vdev->host.bus, vdev->host.slot,
+                         vdev->host.function);
+        } else {
+            error_printf("Warning : Rom loading for device at "
+                         "%04x:%02x:%02x.%x has been disabled due to "
+                         "system instability issues. "
+                         "Specify rombar=1 or romfile to force\n",
+                         vdev->host.domain, vdev->host.bus, vdev->host.slot,
+                         vdev->host.function);
+            return;
+        }
+    }
+
     DPRINTF("%04x:%02x:%02x.%x ROM size 0x%x\n", vdev->host.domain,
             vdev->host.bus, vdev->host.slot, vdev->host.function, size);