[PATCH RFC v4 4/4] iommu/arm-smmu-v3: Wire up shared-SID STE ordering and feature gating

[Peng Fan (OSS)]

From: Peng Fan <peng.fan@xxxxxxx>

For shared SIDs, only the first master to attach writes the STE
(tracked by ste_installed under streams_mutex); subsequent masters
skip the write.  On teardown, skip the ABORT STE write while other
masters still share the SID.

Fault events on shared SIDs cannot be attributed to a specific
master, so arm_smmu_find_master() returns NULL when the stream's
shared_masters list is non-empty.

Disable SVA, IOPF/stall, and vSMMU nesting for shared-SID masters
since all three require unambiguous SID-to-device mapping.

Assisted-by: LLM
Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
---
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c    |  2 +-
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c    |  3 ++
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c        | 43 ++++++++++++++++++++--
 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
index ab1078a97d801..73fb5fad1c181 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
@@ -309,7 +309,7 @@ static int arm_vsmmu_vdevice_init(struct iommufd_vdevice *vdev)
 	 * arm_vsmmu_vsid_to_sid() maps a vSID to master->streams[0] alone, so
 	 * more streams would leave the rest stale and none reads out of bounds.
 	 */
-	if (master->num_streams != 1)
+	if (master->num_streams != 1 || !list_empty(&master->shared_masters_elm))
 		return -EOPNOTSUPP;
 	return 0;
 }
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
index 0a429c64fbf3e..54a0a65669ac2 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
@@ -271,6 +271,9 @@ static int arm_smmu_sva_set_dev_pasid(struct iommu_domain *domain,
 	if (!(master->smmu->features & ARM_SMMU_FEAT_SVA))
 		return -EOPNOTSUPP;
 
+	if (!list_empty(&master->shared_masters_elm))
+		return -EOPNOTSUPP;
+
 	/* Prevent arm_smmu_mm_release from being called while we are attaching */
 	if (!mmget_not_zero(domain->mm))
 		return -EINVAL;
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 0f7e90af5823d..ae33660ca79e7 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2976,11 +2976,36 @@ arm_smmu_get_step_for_sid(struct arm_smmu_device *smmu, u32 sid)
 	}
 }
 
+static bool arm_smmu_is_shared_sid(struct arm_smmu_master *master)
+{
+	return !list_empty(&master->shared_masters_elm);
+}
+
+static bool arm_smmu_skip_shared_ste(struct arm_smmu_device *smmu,
+				     u32 sid, bool is_abort)
+{
+	struct arm_smmu_stream *stream;
+
+	lockdep_assert_held(&smmu->streams_mutex);
+
+	stream = arm_smmu_find_stream(smmu, sid);
+	if (!stream || list_empty(&stream->shared_masters))
+		return false;
+
+	if (is_abort)
+		return true;
+	if (stream->ste_installed)
+		return true;
+	stream->ste_installed = true;
+	return false;
+}
+
 void arm_smmu_install_ste_for_dev(struct arm_smmu_master *master,
 				  const struct arm_smmu_ste *target)
 {
 	int i, j;
 	struct arm_smmu_device *smmu = master->smmu;
+	bool is_abort;
 
 	master->cd_table.in_ste =
 		FIELD_GET(STRTAB_STE_0_CFG, le64_to_cpu(target->data[0])) ==
@@ -2989,10 +3014,12 @@ void arm_smmu_install_ste_for_dev(struct arm_smmu_master *master,
 		FIELD_GET(STRTAB_STE_1_EATS, le64_to_cpu(target->data[1])) ==
 		STRTAB_STE_1_EATS_TRANS;
 
+	is_abort = FIELD_GET(STRTAB_STE_0_CFG, le64_to_cpu(target->data[0])) ==
+		   STRTAB_STE_0_CFG_ABORT;
+
 	for (i = 0; i < master->num_streams; ++i) {
 		u32 sid = master->streams[i].id;
-		struct arm_smmu_ste *step =
-			arm_smmu_get_step_for_sid(smmu, sid);
+		struct arm_smmu_ste *step;
 
 		/* Bridged PCI devices may end up with duplicated IDs */
 		for (j = 0; j < i; j++)
@@ -3001,6 +3028,16 @@ void arm_smmu_install_ste_for_dev(struct arm_smmu_master *master,
 		if (j < i)
 			continue;
 
+		if (arm_smmu_is_shared_sid(master)) {
+			mutex_lock(&smmu->streams_mutex);
+			if (arm_smmu_skip_shared_ste(smmu, sid, is_abort)) {
+				mutex_unlock(&smmu->streams_mutex);
+				continue;
+			}
+			mutex_unlock(&smmu->streams_mutex);
+		}
+
+		step = arm_smmu_get_step_for_sid(smmu, sid);
 		arm_smmu_write_ste(master, sid, step, target);
 	}
 }
@@ -3149,7 +3186,7 @@ static int arm_smmu_enable_iopf(struct arm_smmu_master *master,
 		return 0;
 
 	/* We're not keeping track of SIDs in fault events */
-	if (master->num_streams != 1)
+	if (master->num_streams != 1 || arm_smmu_is_shared_sid(master))
 		return -EOPNOTSUPP;
 
 	if (master->iopf_refcount) {

-- 
2.34.1