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Re: [Xen-devel] [PATCH v7] VT-d: use correct BDF for VF to search VT-d unit

On Tue, Aug 22, 2017 at 06:43:49AM -0600, Jan Beulich wrote:
>>>> On 21.08.17 at 23:52, <chao.gao@xxxxxxxxx> wrote:
>> --- a/xen/include/xen/pci.h
>> +++ b/xen/include/xen/pci.h
>> @@ -39,6 +39,10 @@
>>  #define PCI_SBDF3(s,b,df) ((((s) & 0xffff) << 16) | PCI_BDF2(b, df))
>>  struct pci_dev_info {
>> +    /*
>> +     * When 'is_virtfn' is set, 'is_extfn' is re-used to indicate whether
>> +     * the PF of this VF is an extended function.
>> +     */
>I'd be inclined to extend the comment by appending ", as a VF itself
>can never be an extended function." Is that correct? If so, would

Hi, Jan and Roger.

Strictly speaking, the VF can be an extended function. The definition is
within ARI device (in this kind of device, device field is treated as an
extension of function number) and function number is greater than 7. But
this field isn't used as we don't care about whether a VF is or not an
extended function (at least at present).

Eric reviewed this patch and told me we may match
'if ( pdev->info.is_extfn )' in acpi_find_matched_drhd_unit.
So we may introduce a new field like what I do in v6 or check
'pdev->info.is_virtfn' first in acpi_find_matched_drhd_unit (maybe other
places we check pdev->info.is_extfn).

Which one do you prefer?


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