virtio-pci: change virtio balloon PCI class code

Currently the virtio balloon device, when using the virtio-pci interface
advertises itself with PCI class code MEMORY_RAM.  This is wrong; the
balloon is vaguely related to memory, but is nothing like a PCI memory
device in the meaning of the class code, and this code is not required
or suggested by the virtio PCI specification.

Worse, this patch causes problems on the pseries machine, because the
firmware, seeing this class code, advertises the device as memory in the
device tree, and then a guest kernel bug causes it to see this "memory"
before the real system memory, leading to a crash in early boot.

This patch fixes the problem by removing the bogus PCI class code on the
balloon device.  The backwards compatibility PC machines get new compat
properties so that they don't change.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 0f61f00181a5780b4b8ccb89417341bd595760c9..5c08245fede26e615cb9277790cca0048e7c94b2 100644 (file)
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -28,6 +28,7 @@
 #include "pc.h"
 #include "apic.h"
 #include "pci.h"
+#include "pci_ids.h"
 #include "net.h"
 #include "boards.h"
 #include "ide.h"
@@ -368,6 +369,10 @@ static QEMUMachine pc_machine_v1_1 = {
             .driver   = "isa-fdc",\
             .property = "check_media_rate",\
             .value    = "off",\
+        }, {\
+            .driver   = "virtio-balloon-pci",\
+            .property = "class",\
+            .value    = stringify(PCI_CLASS_MEMORY_RAM),\
         }
 
 static QEMUMachine pc_machine_v1_0 = {

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index a0fb7c1b9ccf9734cd81bfb38c22a0e0dd9e8cad..4a4413d52c2bd0294974373f5e7b28a479c7d3e2 100644 (file)
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -790,6 +790,11 @@ static int virtio_balloon_init_pci(PCIDevice *pci_dev)
     VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
     VirtIODevice *vdev;
 
+    if (proxy->class_code != PCI_CLASS_OTHERS &&
+        proxy->class_code != PCI_CLASS_MEMORY_RAM) { /* qemu < 1.1 */
+        proxy->class_code = PCI_CLASS_OTHERS;
+    }
+
     vdev = virtio_balloon_init(&pci_dev->qdev);
     if (!vdev) {
         return -1;
@@ -906,6 +911,7 @@ static TypeInfo virtio_serial_info = {
 
 static Property virtio_balloon_properties[] = {
     DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
+    DEFINE_PROP_HEX32("class", VirtIOPCIProxy, class_code, 0),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -919,7 +925,7 @@ static void virtio_balloon_class_init(ObjectClass *klass, void *data)
     k->vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET;
     k->device_id = PCI_DEVICE_ID_VIRTIO_BALLOON;
     k->revision = VIRTIO_PCI_ABI_VERSION;
-    k->class_id = PCI_CLASS_MEMORY_RAM;
+    k->class_id = PCI_CLASS_OTHERS;
     dc->reset = virtio_pci_reset;
     dc->props = virtio_balloon_properties;
 }