Re: [PATCH v4 10/15] iommu/arm-smmu-v3: Support PRI Page Request in arm_smmu_handle_ppr()
From: Jonathan Cameron <hidden>
Date: 2026-09-11 00:14:44
Also in:
linux-iommu, linux-pci, lkml
For a PRI-enabled master, convert every PRIQ entry into an iopf_fault and report it through iommu_report_device_fault(). For an unknown StreamID or a master without PRI enabled, keep the existing LAST-page DENY path. Merge its two messages into one ratelimited line so a faulty device cannot flood the kernel log. Discard any PASID Stop Marker (LRW = 0b100) prior to the fault report and the DENY fallback both, because a Stop Marker does not expect a response. The IOPF infrastructure requires the driver to discard it, as per the doc at iommu_report_device_fault(). This also matches the intel-iommu code. Note that master->pri_enabled will only be set by a later change, once all the PRI paths are ready. Co-developed-by: Barak Biber <redacted> Signed-off-by: Barak Biber <redacted> Co-developed-by: Stefan Kaestle <redacted> Signed-off-by: Stefan Kaestle <redacted> Signed-off-by: Malak Marrid <redacted> Signed-off-by: Nicolin Chen <redacted>
One question inline. I made the error of looking at the spec and got confused. Jonathan
quoted hunk ↗ jump to hunk
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c index 43a6029cef43..c631c6344685 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c@@ -2370,6 +2370,7 @@ static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev) static void arm_smmu_handle_ppr(struct arm_smmu_device *smmu, u64 *evt) { + struct arm_smmu_master *master; u32 sid, ssid; u16 grpid; bool ssv, last;@@ -2380,9 +2381,47 @@ static void arm_smmu_handle_ppr(struct arm_smmu_device *smmu, u64 *evt) last = FIELD_GET(PRIQ_0_PRG_LAST, evt[0]); grpid = FIELD_GET(PRIQ_1_PRG_IDX, evt[1]); - dev_info(smmu->dev, "unexpected PRI request received:\n"); - dev_info(smmu->dev, - "\tsid 0x%08x.0x%05x: [%u%s] %sprivileged %s%s%s access at iova 0x%016llx\n", + /* + * A PASID Stop Marker (LRW = 0b100) does not expect a response and + * must be discarded before fault reporting: see the documentation + * at iommu_report_device_fault(). + */ + if (last && !(evt[0] & (PRIQ_0_PERM_READ | PRIQ_0_PERM_WRITE)))
There is a bit of spec language about case where there is no PASID LWR=0xb100 not being a stop marker, SSV == 0 and should be treated as a PRI request. I'm not sure what that means in practice but maybe a comment on why that case doesn't matter. Feels like breadcrumbs we might need in future. -- Jonathan Cameron [off-list ref]