Re: [Xen-devel] [PATCH v5] VT-d: fix VF of RC integrated PF matched to wrong VT-d unit

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Gao, Chao
> Sent: Thursday, July 6, 2017 3:58 PM
> 
> The problem is for a VF of RC integrated PF (e.g. PF's BDF is 00:02.0),
> we would wrongly use 00:00.0 to search VT-d unit.
> 
> If a PF is an extended function, the BDF of a traditional function within the
> same device should be used to search VT-d unit. Otherwise, the real BDF of
> PF
> should be used. According PCI-e spec, an extended function is a function
> within an ARI device and Function Number is greater than 7. The original
> code
> tried to tell apart them through checking PCI_SLOT(), missing counterpart of
> pci_ari_enabled() (this function exists in linux kernel) compared to linux
> kernel. Without checking whether ARI is enabled, it incurs a RC integrated PF
> with PCI_SLOT() >0 is wrongly classified to an extended function. Note that a
> RC integrated function isn't within an ARI device and thus cannot be
> extended
> function and in this case the real BDF should be used.
> 
> Considering 'is_extfn' field of struct pci_dev has been passed down from
> Domain0 to indicate whether the function is an extended function, this patch
> just looks up the 'is_extfn' field of PF's struct pci_dev and set 'devfn' to 0
> when 'is_extfn' is true.
> 
> Reported-by: Crawford, Eric R <Eric.R.Crawford@xxxxxxxxx>
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>

Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>

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