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Re: [PATCH] vfio/pci: Don't setup VFIO MSI-X for Kunlun VF
From: |
Alex Williamson |
Subject: |
Re: [PATCH] vfio/pci: Don't setup VFIO MSI-X for Kunlun VF |
Date: |
Tue, 21 Dec 2021 12:16:15 -0700 |
On Tue, 14 Dec 2021 13:45:34 +0800
Cai Huoqing <cai.huoqing@linux.dev> wrote:
> No support MSI-X in BAIDU KUNLUN Virtual Function devices,
> so add a quirk to avoid setuping VFIO MSI-X
>
> Signed-off-by: Cai Huoqing <cai.huoqing@linux.dev>
> ---
> hw/vfio/pci.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 7b45353ce2..15f76bbe56 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -1994,6 +1994,13 @@ static int vfio_add_std_cap(VFIOPCIDevice *vdev,
> uint8_t pos, Error **errp)
> ret = vfio_setup_pcie_cap(vdev, pos, size, errp);
> break;
> case PCI_CAP_ID_MSIX:
> + /*
> + * BAIDU KUNLUN Virtual Function devices for KUNLUN AI processor
> + * don't support MSI-X, so don't setup VFIO MSI-X here.
> + */
> + if (vdev->vendor_id == PCI_VENDOR_ID_BAIDU &&
> + vdev->device_id == PCI_DEVICE_ID_KUNLUN_VF)
> + break;
> ret = vfio_msix_setup(vdev, pos, errp);
> break;
> case PCI_CAP_ID_PM:
So the VF exposes an MSI-X capability but it's entirely unsupported
and/or bogus? If it's not bogus, why can't we support it? How does
the host kernel driver know to avoid MSI-X? Should we use the same
mechanism used by the host driver to quirk whether vfio-pci exposes the
MSI-X capability to userspace at all? Thanks,
Alex