[PATCH 5/7] iommu/arm-smmu-v3: Move the DMA API comment to flush_iotlb_all

[Jason Gunthorpe]

arm_smmu_tlb_inv_context() is the wrong flush_all for this comment,
it is only called during io-pgtable destruction not during the dma-iommu
operation. Move it to arm_smmu_flush_iotlb_all() which is the flush
that is triggered by the dma-iommu lazy flush thread.

Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 31 +++++++++++----------
 1 file changed, 16 insertions(+), 15 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 5087603ea18e62..dd22c0f881bfba 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2392,21 +2392,6 @@ static void arm_smmu_tlb_inv_context(void *cookie)
 {
 	struct arm_smmu_domain *smmu_domain = cookie;
 
-	/*
-	 * If the DMA API is running in non-strict mode then another CPU could
-	 * have changed the page table and not invoked any flush op. Instead the
-	 * other CPU will do an atomic_read() and this CPU will have done an
-	 * atomic_write(). That handshake is enough to acquire the page table
-	 * writes from the other CPU.
-	 *
-	 * All command execution has a dma_wmb() to release all the in-memory
-	 * structures written by this CPU, that barrier must also release the
-	 * writes acquired from all the other CPUs too.
-	 *
-	 * There are other barriers and atomics on this path, but the above is
-	 * the essential mechanism for ensuring that HW sees the page table
-	 * writes from another CPU before it executes the IOTLB invalidation.
-	 */
 	arm_smmu_domain_inv(smmu_domain);
 }
 
@@ -4078,6 +4063,22 @@ static void arm_smmu_flush_iotlb_all(struct iommu_domain *domain)
 {
 	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
 
+	/*
+	 * If the DMA API is running in non-strict mode then another CPU could
+	 * have changed the page table and not invoked any flush op. Instead the
+	 * other CPU will do an atomic_read() and this CPU will have done an
+	 * atomic_write(). That handshake is enough to acquire the page table
+	 * writes from the other CPU.
+	 *
+	 * All command execution has a dma_wmb() to release all the in-memory
+	 * structures written by this CPU, that barrier must also release the
+	 * writes acquired from all the other CPUs too.
+	 *
+	 * There are other barriers and atomics on this path, but the above is
+	 * the essential mechanism for ensuring that HW sees the page table
+	 * writes from another CPU before it executes the IOTLB invalidation.
+	 */
+
 	if (smmu_domain->smmu)
 		arm_smmu_tlb_inv_context(smmu_domain);
 }
-- 
2.43.0