virtio/pci: Size the MSI-X bar according to the number of MSI-X

Since 45d3b59e8c45 ("kvm tools: Increase amount of possible interrupts
per PCI device"), the number of MSI-S has gone from 4 to 33.

However, the corresponding storage hasn't been upgraded, and writing
to the MSI-X table is a pretty risky business. Now that the Linux
kernel writes to *all* MSI-X entries before doing anything else
with the device, kvmtool dies a horrible death.

Fix it by properly defining the size of the MSI-X bar, and make
Linux great again.

Signed-off-by: Marc Zyngier <>
1 file changed