[PATCH v6 18/25] iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

The invalidate_range() notifier is called for any change to the address
space. Perform the required ATC invalidations.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 drivers/iommu/arm-smmu-v3.c | 56 ++++++++++++++++++++++++++++++-------
 1 file changed, 46 insertions(+), 10 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 00e5b69bb81a5..c65937d953b5f 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -742,7 +742,7 @@ struct arm_smmu_mmu_notifier {
 	struct arm_smmu_ctx_desc	*cd;
 	bool				cleared;
 	refcount_t			refs;
-	struct arm_smmu_domain		*domain;
+	struct arm_smmu_domain __rcu	*domain;
 };
 
 #define mn_to_smmu(mn) container_of(mn, struct arm_smmu_mmu_notifier, mn)
@@ -2396,6 +2396,20 @@ arm_smmu_atc_inv_to_cmd(int ssid, unsigned long iova, size_t size,
 	size_t inval_grain_shift = 12;
 	unsigned long page_start, page_end;
 
+	/*
+	 * ATS and PASID:
+	 *
+	 * If substream_valid is clear, the PCIe TLP is sent without a PASID
+	 * prefix. In that case all ATC entries within the address range are
+	 * invalidated, including those that were requested with a PASID! There
+	 * is no way to invalidate only entries without PASID.
+	 *
+	 * When using STRTAB_STE_1_S1DSS_SSID0 (reserving CD 0 for non-PASID
+	 * traffic), translation requests without PASID create ATC entries
+	 * without PASID, which must be invalidated with substream_valid clear.
+	 * This has the unpleasant side-effect of invalidating all PASID-tagged
+	 * ATC entries within the address range.
+	 */
 	*cmd = (struct arm_smmu_cmdq_ent) {
 		.opcode			= CMDQ_OP_ATC_INV,
 		.substream_valid	= !!ssid,
@@ -2439,12 +2453,12 @@ arm_smmu_atc_inv_to_cmd(int ssid, unsigned long iova, size_t size,
 	cmd->atc.size	= log2_span;
 }
 
-static int arm_smmu_atc_inv_master(struct arm_smmu_master *master)
+static int arm_smmu_atc_inv_master(struct arm_smmu_master *master, int ssid)
 {
 	int i;
 	struct arm_smmu_cmdq_ent cmd;
 
-	arm_smmu_atc_inv_to_cmd(0, 0, 0, &cmd);
+	arm_smmu_atc_inv_to_cmd(ssid, 0, 0, &cmd);
 
 	for (i = 0; i < master->num_sids; i++) {
 		cmd.atc.sid = master->sids[i];
@@ -2958,7 +2972,7 @@ static void arm_smmu_disable_ats(struct arm_smmu_master *master)
 	 * ATC invalidation via the SMMU.
 	 */
 	wmb();
-	arm_smmu_atc_inv_master(master);
+	arm_smmu_atc_inv_master(master, 0);
 	atomic_dec(&smmu_domain->nr_ats_masters);
 }
 
@@ -3187,7 +3201,22 @@ static void arm_smmu_mm_invalidate_range(struct mmu_notifier *mn,
 					 struct mm_struct *mm,
 					 unsigned long start, unsigned long end)
 {
-	/* TODO: invalidate ATS */
+	struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn);
+	struct arm_smmu_domain *smmu_domain;
+
+	rcu_read_lock();
+	smmu_domain = rcu_dereference(smmu_mn->domain);
+	if (smmu_domain) {
+		/*
+		 * Ensure that mm->pasid is valid. Pairs with the
+		 * smp_store_release() from rcu_assign_pointer() in
+		 * __arm_smmu_sva_bind()
+		 */
+		smp_rmb();
+		arm_smmu_atc_inv_domain(smmu_domain, mm->pasid, start,
+					end - start + 1);
+	}
+	rcu_read_unlock();
 }
 
 static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
@@ -3201,7 +3230,8 @@ static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
 		return;
 	}
 
-	smmu_domain = smmu_mn->domain;
+	smmu_domain = rcu_dereference_protected(smmu_mn->domain,
+			lockdep_is_held(&arm_smmu_sva_lock));
 
 	/*
 	 * DMA may still be running. Keep the cd valid but disable
@@ -3210,7 +3240,7 @@ static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
 	arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, &invalid_cd);
 
 	arm_smmu_tlb_inv_asid(smmu_domain->smmu, smmu_mn->cd->asid);
-	/* TODO: invalidate ATS */
+	arm_smmu_atc_inv_domain(smmu_domain, mm->pasid, 0, 0);
 
 	smmu_mn->cleared = true;
 	mutex_unlock(&arm_smmu_sva_lock);
@@ -3251,7 +3281,8 @@ __arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm)
 		return ERR_CAST(mn);
 
 	smmu_mn = mn_to_smmu(mn);
-	if (smmu_mn->domain)
+	if (rcu_dereference_protected(smmu_mn->domain,
+				      lockdep_is_held(&arm_smmu_sva_lock)))
 		refcount_inc(&smmu_mn->refs);
 
 	bond = kzalloc(sizeof(*bond), GFP_KERNEL);
@@ -3277,7 +3308,11 @@ __arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm)
 
 	bond->sva.dev = dev;
 	list_add(&bond->list, &master->bonds);
-	smmu_mn->domain = smmu_domain;
+	/*
+	 * Initialize domain last, since the invalidate() notifier assumes a
+	 * valid mm->pasid after fetching a valid domain.
+	 */
+	rcu_assign_pointer(smmu_mn->domain, smmu_domain);
 	return &bond->sva;
 
 err_free_pasid:
@@ -3318,7 +3353,8 @@ static void __arm_smmu_sva_unbind(struct iommu_sva *handle)
 		if (!smmu_mn->cleared) {
 			arm_smmu_tlb_inv_asid(smmu_domain->smmu,
 					      smmu_mn->cd->asid);
-			/* TODO: invalidate ATS */
+			arm_smmu_atc_inv_domain(smmu_domain, bond->mm->pasid,
+						0, 0);
 		}
 	}
 
-- 
2.26.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel