On Mon, Jul 01, 2024 at 08:26:05PM +0000, Wei Liu wrote:
> The intent of the code snippet is to always return 0 for both
> PCI_INTERRUPT_LINE and PCI_INTERRUPT_PIN.
>
> The check misses PCI_INTERRUPT_PIN. This patch fixes that.
>
> This is discovered by this call in VFIO:
>
> pci_read_config_byte(vdev->pdev, PCI_INTERRUPT_PIN, &pin);
>
> The old code does not set *val to 0 because it misses the check for
> PCI_INTERRUPT_PIN. Garbage is returned in that case.
>
> Fixes: 4daace0d8ce8 ("PCI: hv: Add paravirtual PCI front-end for Microsoft Hyper-V VMs")
> Cc: stable@xxxxxxxxxx
> Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx>
> Reviewed-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
Bjorn & other PCI maintainers, do you want to pick this up via your
tree?
I can pick this up via the hyperv tree if you prefer.
Thanks,
Wei.
> ---
> v3:
> * Change commit subject line and message per Bjorn's suggestion
> v2:
> * Change the commit subject line and message
> * Change the code according to feedback
> ---
> drivers/pci/controller/pci-hyperv.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 5992280e8110..cdd5be16021d 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -1130,8 +1130,8 @@ static void _hv_pcifront_read_config(struct hv_pci_dev *hpdev, int where,
> PCI_CAPABILITY_LIST) {
> /* ROM BARs are unimplemented */
> *val = 0;
> - } else if (where >= PCI_INTERRUPT_LINE && where + size <=
> - PCI_INTERRUPT_PIN) {
> + } else if ((where >= PCI_INTERRUPT_LINE && where + size <= PCI_INTERRUPT_PIN) ||
> + (where >= PCI_INTERRUPT_PIN && where + size <= PCI_MIN_GNT)) {
> /*
> * Interrupt Line and Interrupt PIN are hard-wired to zero
> * because this front-end only supports message-signaled
> --
> 2.43.0
>
