[PATCH] hw/pci: migration: Skip config space check for vendor specific capability during restore/load

[Vinayak Kale]

In case of migration, during restore operation, qemu checks the config space of 
the pci device with the config space
in the migration stream captured during save operation. In case of config space 
data mismatch, restore operation is failed.

config space check is done in function get_pci_config_device(). By default VSC 
(vendor-specific-capability) in config space is checked.

Ideally qemu should not check VSC during restore/load. This patch skips the 
check by not setting pdev->cmask[] for VSC offsets in pci_add_capability().
If cmask[] is not set for an offset, then qemu skips config space check for 
that offset.

Signed-off-by: Vinayak Kale <vkale@nvidia.com>
---
 hw/pci/pci.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 76080af580..32429109df 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -2485,8 +2485,11 @@ int pci_add_capability(PCIDevice *pdev, uint8_t cap_id,
     memset(pdev->used + offset, 0xFF, QEMU_ALIGN_UP(size, 4));
     /* Make capability read-only by default */
     memset(pdev->wmask + offset, 0, size);
-    /* Check capability by default */
-    memset(pdev->cmask + offset, 0xFF, size);
+
+    if (cap_id != PCI_CAP_ID_VNDR) {
+        /* Check non-vendor specific capability by default */
+        memset(pdev->cmask + offset, 0xFF, size);
+    }
     return offset;
 }
 
-- 
2.34.1