On 2023/8/21 14:33, Tian, Kevin wrote:
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: Bindprocessaddress 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 theThis 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...
We attempted to do this in the patch linked below. https://lore.kernel.org/linux-iommu/20220705050710.2887204-5-baolu.lu@xxxxxxxxxxxxxxx/ After long discussion, we decided to move it to the pci_enable_pasid() interface. The non-static single device group is only relevant to PCI fabrics that support hot-plugging without ACS support on the upstream path. Best regards, baolu
