On 28/01/2022 10:36, Jan Beulich wrote:
> On 28.01.2022 10:28, Durrant, Paul wrote:
>> On 27/01/2022 14:47, Jan Beulich wrote:
>>> @@ -1457,24 +1462,24 @@ static int iommu_get_device_group(
>>> if ( !is_iommu_enabled(d) || !ops->get_device_group_id )
>>> return 0;
>>>
>>> - group_id = ops->get_device_group_id(seg, bus, devfn);
>>> + group_id = iommu_call(ops, get_device_group_id, seg, bus, devfn);
>>>
>>> pcidevs_lock();
>>> for_each_pdev( d, pdev )
>>> {
>>> - if ( (pdev->seg != seg) ||
>>> - ((pdev->bus == bus) && (pdev->devfn == devfn)) )
>>> + unsigned int b = pdev->bus;
>>> + unsigned int df = pdev->devfn;
>>> +
>>> + if ( (pdev->seg != seg) || ((b == bus) && (df == devfn)) )
>>> continue;
>>>
>>> - if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (pdev->bus << 8)
>>> | pdev->devfn) )
>>> + if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (b << 8) | df) )
>>> continue;
>>>
>>> - sdev_id = ops->get_device_group_id(seg, pdev->bus, pdev->devfn);
>>> + sdev_id = iommu_call(ops, get_device_group_id, seg, b, df);
>>> if ( (sdev_id == group_id) && (i < max_sdevs) )
>>> {
>>> - bdf = 0;
>>> - bdf |= (pdev->bus & 0xff) << 16;
>>> - bdf |= (pdev->devfn & 0xff) << 8;
>>> + bdf = (b << 16) | (df << 8);
>> Don't we have a macro for this now? Probably best to start using it
>> whilst modifying the code.
> We don't. And it would feel somewhat misleading to use PCI_BDF2(b, df) << 8
> here. The situation is even worse imo: Besides there not being a macro, I
> also cannot seem to find any documentation on this non-standard layout (BDF
> shifted left by 8). Yet then again I also can't spot any caller of
> xc_get_device_group() ...
I'm sure I already did the archaeology.
device groups were broken by a hypercall bounce buffering change 2 years
before the only caller was dropped with Xend.
This mess of a hypercall has demonstrably not been used in a decade. I
firmly suggest dropping it, rather than wasting effort trying to unbreak
an interface which needs deleting anyway as the first step to doing
IOMMU groups.
~Andrew
