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Re: [Xen-devel] [patch v6] vt-d: fix vf of rc integrated pf matched to wrong vt-d unit

on wed, aug 16, 2017 at 01:12:24pm +0800, chao gao wrote:
> 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.

AFAIK, extended functions simply remove the slot and extend the
function number to [0, 255], so it seems correct to expect that the
VT-d unit search should be done using the bus and extended function
parameters, and assume slot is 0. Is this some kind of limitation of

> The original code tried to tell apart Extended
> Function and non-Extended Function 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.
> This patch introduces a new field, pf_is_extfn, in struct
> pci_dev_info, to indicate whether the physical function is an extended
> function. The new field helps to generate correct BDF to search VT-d
> unit.

> diff --git a/xen/include/xen/pci.h b/xen/include/xen/pci.h
> index 59b6e8a..9e76aa0 100644
> --- a/xen/include/xen/pci.h
> +++ b/xen/include/xen/pci.h
> @@ -40,6 +40,7 @@
>  struct pci_dev_info {
>      bool_t is_extfn;
> +    bool_t pf_is_extfn; /* Only valid for virtual function */

Can't you just re-use is_virtfn and is_extfn, and when both are true
it means the pf where this vf belongs is an extended function?

>      bool_t is_virtfn;
>      struct {
>          u8 bus;
> -- 

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