Messages in this thread | | | Date | Mon, 4 May 2020 18:09:16 +0200 | From | Cornelia Huck <> | Subject | Re: [PATCH] vfio-pci: Mask cap zero |
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On Fri, 01 May 2020 15:41:24 -0600 Alex Williamson <alex.williamson@redhat.com> wrote:
> There is no PCI spec defined capability with ID 0, therefore we don't > expect to find it in a capability chain and we use this index in an > internal array for tracking the sizes of various capabilities to handle > standard config space. Therefore if a device does present us with a > capability ID 0, we mark our capability map with nonsense that can > trigger conflicts with other capabilities in the chain. Ignore ID 0 > when walking the capability chain, handling it as a hidden capability. > > Seen on an NVIDIA Tesla T4. > > Signed-off-by: Alex Williamson <alex.williamson@redhat.com> > --- > drivers/vfio/pci/vfio_pci_config.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c > index 87d0cc8c86ad..5935a804cb88 100644 > --- a/drivers/vfio/pci/vfio_pci_config.c > +++ b/drivers/vfio/pci/vfio_pci_config.c > @@ -1487,7 +1487,7 @@ static int vfio_cap_init(struct vfio_pci_device *vdev) > if (ret) > return ret; > > - if (cap <= PCI_CAP_ID_MAX) {
Maybe add a comment:
/* no PCI spec defined capability with ID 0: hide it */
?
> + if (cap && cap <= PCI_CAP_ID_MAX) { > len = pci_cap_length[cap]; > if (len == 0xFF) { /* Variable length */ > len = vfio_cap_len(vdev, cap, pos); >
Is there a requirement for caps to be strictly ordered? If not, could len hold a residual value from a previous iteration?
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