From: Easwar Hariharan <eahariha@linux.microsoft.com>
Date: Thu, 3 Jul 2025 15:54:33 +0000 (-0700)
Subject: iommu/amd: Enable PASID and ATS capabilities in the correct order
X-Git-Tag: v6.16.1~416
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=70d595bc53dc1779d92152e0cd38b7dce5a2f25a;p=thirdparty%2Fkernel%2Fstable.git

iommu/amd: Enable PASID and ATS capabilities in the correct order

[ Upstream commit c694bc8b612ddd0dd70e122a00f39cb1e2e6927f ]

Per the PCIe spec, behavior of the PASID capability is undefined if the
value of the PASID Enable bit changes while the Enable bit of the
function's ATS control register is Set. Unfortunately,
pdev_enable_caps() does exactly that by ordering enabling ATS for the
device before enabling PASID.

Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc: Vasant Hegde <vasant.hegde@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerry Snitselaar <jsnitsel@redhat.com>
Fixes: eda8c2860ab679 ("iommu/amd: Enable device ATS/PASID/PRI capabilities independently")
Signed-off-by: Easwar Hariharan <eahariha@linux.microsoft.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20250703155433.6221-1-eahariha@linux.microsoft.com
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 3117d99cf83d0..8b8d3e843743f 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -634,8 +634,8 @@ static inline void pdev_disable_cap_pasid(struct pci_dev *pdev)
 
 static void pdev_enable_caps(struct pci_dev *pdev)
 {
-	pdev_enable_cap_ats(pdev);
 	pdev_enable_cap_pasid(pdev);
+	pdev_enable_cap_ats(pdev);
 	pdev_enable_cap_pri(pdev);
 }