Re: [Xen-devel] [PATCH v10] VT-d: use correct BDF for VF to search VT-d unit

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.08.17 at 04:42, <chao.gao@xxxxxxxxx> wrote:
> When SR-IOV is enabled, 'Virtual Functions' of a 'Physical Function'
> are under the scope of the same VT-d unit as the 'Physical Function'.
> A 'Physical Function' can be a 'Traditional Function' or an ARI
> 'Extended Function'. And furthermore, 'Extended Functions' on an
> endpoint are under the scope of the same VT-d unit as the 'Traditional
> Functions' on the endpoint. To search VT-d unit for a VF, if its PF
> isn't an extended function, the BDF of PF should be used. Otherwise
> the BDF of a traditional function in the same device with the PF
> should be used.
> 
> Current code uses PCI_SLOT() to recognize an ARI 'Extended Funcion'.
> But it is conceptually wrong w/o checking whether PF is an extended
> function and would lead to match VFs of a RC integrated PF to a wrong
> VT-d unit.
> 
> This patch overrides VF 'is_extfn' field and uses this field to
> indicate whether the PF of this VF is an extended function. The field
> helps to use correct BDF to search VT-d unit.
> 
> Reported-by: Crawford, Eric R <Eric.R.Crawford@xxxxxxxxx>
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>

Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
albeit ...

> --- a/xen/drivers/passthrough/vtd/dmar.c
> +++ b/xen/drivers/passthrough/vtd/dmar.c
> @@ -211,15 +211,15 @@ struct acpi_drhd_unit 
> *acpi_find_matched_drhd_unit(const struct pci_dev *pdev)
>      if ( pdev == NULL )
>          return NULL;
>  
> -    if ( pdev->info.is_extfn )
> +    if ( pdev->info.is_virtfn )
>      {
> -        bus = pdev->bus;
> -        devfn = 0;
> +        bus = pdev->info.physfn.bus;
> +        devfn = (!pdev->info.is_extfn) ? pdev->info.physfn.devfn : 0;

... if I end up committing this and if I don't forget, I'll likely take the
liberty to remove the pointless parentheses here.

Jan


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