Re: [PATCH 2/2] iommu/arm-smmu-v3: Report stalled S2 events
From: Robin Murphy <robin.murphy@arm.com>
Date: 2024-08-13 11:57:05
Also in:
linux-iommu, lkml
On 12/08/2024 9:52 pm, Mostafa Saleh wrote:
quoted hunk ↗ jump to hunk
Previously, S2 stall was disabled and in case there was an event it wouldn't be reported on the assumption that it's always pinned by VFIO. However, now since we can enable stall, devices that use S2 outside VFIO should be able to report the stalls similar to S1. Also, to keep the old behaviour were S2 events from nested domains were not reported as they are pinned (from VFIO) add a new flag to track this. Signed-off-by: Mostafa Saleh <smostafa@google.com> --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 18 +++++++++++++----- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 2 ++ 2 files changed, 15 insertions(+), 5 deletions(-)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 8d573d9ca93c..ffa865529d73 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c@@ -1733,6 +1733,7 @@ static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt) u32 sid = FIELD_GET(EVTQ_0_SID, evt[0]); struct iopf_fault fault_evt = { }; struct iommu_fault *flt = &fault_evt.fault; + struct arm_smmu_domain *smmu_domain; switch (FIELD_GET(EVTQ_0_ID, evt[0])) { case EVT_ID_TRANSLATION_FAULT:@@ -1744,10 +1745,6 @@ static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt) return -EOPNOTSUPP; } - /* Stage-2 is always pinned at the moment */ - if (evt[1] & EVTQ_1_S2) - return -EFAULT; - if (!(evt[1] & EVTQ_1_STALL)) return -EOPNOTSUPP;@@ -1782,6 +1779,15 @@ static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt) goto out_unlock; } + /* It is guaranteed that smmu_domain exists as EVTQ_1_STALL is checked. */ + smmu_domain = to_smmu_domain(iommu_get_domain_for_dev(master->dev)); + + /* nesting domain is always pinned at the moment */ + if (smmu_domain->enable_nesting) {
Ugh, has the whole enable_nesting method still not gone away already? However, at least for now, isn't this functionally equivalent to just testing !(smmu->features & ARM_SMMU_FEAT_TRANS_S1) anyway? We still won't be able to differentiate a nominally-pinned non-nested VFIO domain from a nominally-stallable non-VFIO domain on S2-only hardware. Thanks, Robin.
quoted hunk ↗ jump to hunk
+ ret = -EINVAL; + goto out_unlock; + } + iommu_report_device_fault(master->dev, &fault_evt); out_unlock: mutex_unlock(&smmu->streams_mutex);@@ -3373,8 +3379,10 @@ static int arm_smmu_enable_nesting(struct iommu_domain *domain) mutex_lock(&smmu_domain->init_mutex); if (smmu_domain->smmu) ret = -EPERM; - else + else { smmu_domain->stage = ARM_SMMU_DOMAIN_S2; + smmu_domain->enable_nesting = true; + } mutex_unlock(&smmu_domain->init_mutex); return ret;diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h index 0dc7ad43c64c..f66efeec2cf8 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h@@ -745,6 +745,8 @@ struct arm_smmu_domain { spinlock_t devices_lock; struct mmu_notifier mmu_notifier; + + bool enable_nesting; }; /* The following are exposed for testing purposes. */