Re: [PATCH RFC] pci: fix device presence detection for VFs

From: Wei Gong
Date: Tue Oct 25 2022 - 23:39:44 EST


On Mon, Oct 10, 2022 at 01:12:20PM -0400, Michael S. Tsirkin wrote:
> virtio uses the same driver for VFs and PFs. Accordingly,
> pci_device_is_present is used to detect device presence. This function
> isn't currently working properly for VFs since it attempts reading
> device and vendor ID. Result is device marked broken incorrectly. As
> VFs are present if and only if PF is present, just return the value for
> that device.
>
> Reported-by: gongwei <gongwei833x@xxxxxxxxx>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

Tested-by: Wei Gong <gongwei833x@xxxxxxxxx>

>
> ---
>
> Warning - compile tested only. gongwei could you help test and report
> please?

Tested and working well. Any plans for next steps?

>
> drivers/pci/pci.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 95bc329e74c0..ba29b8e2f3c1 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -6462,6 +6462,9 @@ bool pci_device_is_present(struct pci_dev *pdev)
> {
> u32 v;
>
> + if (pdev->is_virtfn)
> + return pci_device_is_present(pdev->physfn);
> +
> if (pci_dev_is_disconnected(pdev))
> return false;
> return pci_bus_read_dev_vendor_id(pdev->bus, pdev->devfn, &v, 0);
> --
> MST
>