> From: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx> > Sent: Monday, August 21, 2023 1:45 PM > > On 2023/8/18 11:56, Tian, Kevin wrote: > >> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> > >> Sent: Monday, August 14, 2023 9:18 AM > >> > >> The PASID interfaces have always supported only single-device groups. > >> This was first introduced in commit 26b25a2b98e45 ("iommu: Bind > process > >> address spaces to devices"), and has been kept consistent in subsequent > >> commits. > >> > >> However, the core code doesn't explicitly check for this requirement > >> after commit 201007ef707a8 ("PCI: Enable PASID only when ACS RR & UF > >> enabled on upstream path"), which made this requirement implicit. > >> > >> Restore the check to make it explicit that the PASID interfaces only > >> support devices belonging to single-device groups. > >> > >> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> > >> --- > >> drivers/iommu/iommu.c | 5 +++++ > >> 1 file changed, 5 insertions(+) > >> > >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > >> index 71b9c41f2a9e..f1eba60e573f 100644 > >> --- a/drivers/iommu/iommu.c > >> +++ b/drivers/iommu/iommu.c > >> @@ -3408,6 +3408,11 @@ int iommu_attach_device_pasid(struct > >> iommu_domain *domain, > >> return -ENODEV; > >> > >> mutex_lock(&group->mutex); > >> + if (list_count_nodes(&group->devices) != 1) { > >> + ret = -EINVAL; > >> + goto out_unlock; > >> + } > >> + > > > > I wonder whether we should also block adding new device to this > > group once the single-device has pasid enabled. Otherwise the > > This has been guaranteed by pci_enable_pasid(): > > if (!pci_acs_path_enabled(pdev, NULL, PCI_ACS_RR | PCI_ACS_UF)) > return -EINVAL; > well since you are adding generic core check then it's not good to rely on the fact of a specific bus...