Re: [PATCH] virtio: Fix crash when sriov-pf is set for non-PCI-Express device

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Thu, Dec 04, 2025 at 06:26:57PM +0100, Kevin Wolf wrote:
> Setting the sriov-pf property on devices that aren't PCI Express causes
> an assertion failure:
> 
>     $ qemu-system-x86_64 \
>         -blockdev null-co,node-name=null \
>         -blockdev null-co,node-name=null2 \
>         -device virtio-blk,drive=null,id=pf \
>         -device virtio-blk,sriov-pf=pf,drive=null2
>     qemu-system-x86_64: ../hw/pci/pcie.c:1062: void pcie_add_capability(PCIDevice *, uint16_t, uint8_t, uint16_t, uint16_t): Assertion `offset >= PCI_CONFIG_SPACE_SIZE' failed.
> 
> This is because proxy->last_pcie_cap_offset is only initialised to a
> non-zero value in virtio_pci_realize() if it's a PCI Express device, and
> then virtio_pci_device_plugged() still tries to use it.
> 
> To fix this, just skip the SR-IOV code for !pci_is_express(). Then the
> next thing pci_qdev_realize() does is call pcie_sriov_register_device(),
> which returns the appropriate error.
> 
> Cc: qemu-stable@nongnu.org
> Fixes: d0c280d3fac6 ('pcie_sriov: Make a PCI device with user-created VF ARI-capable')
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  hw/virtio/virtio-pci.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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