Am 11.01.23 um 15:20 schrieb Jason Gunthorpe:
On Wed, Jan 11, 2023 at 03:17:03PM +0100, Christian König wrote:
Am 11.01.23 um 15:14 schrieb Jason Gunthorpe:
On Wed, Jan 11, 2023 at 09:54:03PM +0800, Baolu Lu wrote:
On 2023/1/11 21:44, Jason Gunthorpe wrote:
iommu_enable_pci_caps() in the Intel IOMMU driver. This also does some
handling for ATS, so here we could check the info->ats_supported flag if ACS
needs to be checked or not.
*groan* this is seems wrong 🙁 Lu why are we doing this inside iommu
drivers instead of in the device drivers to declare they want to use
PASID?
Currently it's common to enable pasid in the IOMMU drivers, but device
driver has more knowledge of the device, hence it makes more sense to
move pci_enable_pasid() to the device driver.
So, lets fix it that way.
Add the flag to the pci_enable_pasid(), set the flag in the AMD
IOMMU's special AMD GPU only path assuming the device will always use
ATS
That will fix at least this the AMD use case.
Do not set the flag in the other iommu drivers
Don't we have other hardware which supports ATS as well and might run into
the same problem?
As I said, I think we have only 1 user of the common PASID API and it
was happy with things as-is, so I think for v6.2 we are fine.
Honestly, not declaring ACS in a 'enterprise' multi-function device is
already kind of sketchy/rare - even if ATS saves things for the PASID
case.
Yeah, as I said I've checked a couple of different AMD hardware. And
what I have available always has ACS, ATS, PRI and PASID enabled together.
That there is a Carizzo variant which enables ATS/PASID but not ACS is
indeed a bit strange.
Christian.
Jason
