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| author | Lu Baolu <baolu.lu@linux.intel.com> | 2025-09-18 13:02:02 +0800 |
|---|---|---|
| committer | Joerg Roedel <joerg.roedel@amd.com> | 2025-09-19 09:43:21 +0200 |
| commit | 5ef7e24c742038a5d8c626fdc0e3a21834358341 (patch) | |
| tree | 181a852a606d1c1b25a228db4fafadf11a0ec693 /drivers/iommu/intel/iommu.c | |
| parent | 4402e8f39d0bfff5c0a5edb5e1afe27a56545e11 (diff) | |
iommu/vt-d: PRS isn't usable if PDS isn't supported
The specification, Section 7.10, "Software Steps to Drain Page Requests &
Responses," requires software to submit an Invalidation Wait Descriptor
(inv_wait_dsc) with the Page-request Drain (PD=1) flag set, along with
the Invalidation Wait Completion Status Write flag (SW=1). It then waits
for the Invalidation Wait Descriptor's completion.
However, the PD field in the Invalidation Wait Descriptor is optional, as
stated in Section 6.5.2.9, "Invalidation Wait Descriptor":
"Page-request Drain (PD): Remapping hardware implementations reporting
Page-request draining as not supported (PDS = 0 in ECAP_REG) treat this
field as reserved."
This implies that if the IOMMU doesn't support the PDS capability, software
can't drain page requests and group responses as expected.
Do not enable PCI/PRI if the IOMMU doesn't support PDS.
Reported-by: Joel Granados <joel.granados@kernel.org>
Closes: https://lore.kernel.org/r/20250909-jag-pds-v1-1-ad8cba0e494e@kernel.org
Fixes: 66ac4db36f4c ("iommu/vt-d: Add page request draining support")
Cc: stable@vger.kernel.org
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20250915062946.120196-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Diffstat (limited to 'drivers/iommu/intel/iommu.c')
| -rw-r--r-- | drivers/iommu/intel/iommu.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 9c3ab9d9f69a..92759a8f8330 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -3812,7 +3812,7 @@ static struct iommu_device *intel_iommu_probe_device(struct device *dev) } if (info->ats_supported && ecap_prs(iommu->ecap) && - pci_pri_supported(pdev)) + ecap_pds(iommu->ecap) && pci_pri_supported(pdev)) info->pri_supported = 1; } } |