From: Will Deacon <will@kernel.org>
Date: Wed, 21 Aug 2019 11:38:15 +0000 (+0100)
Subject: iommu/arm-smmu-v3: Don't issue CMD_SYNC for zero-length invalidations
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=7314ca8699e1defd6f2883f203c0e828a4f51f9f;p=linux.git

iommu/arm-smmu-v3: Don't issue CMD_SYNC for zero-length invalidations

Calling arm_smmu_tlb_inv_range() with a size of zero, perhaps due to
an empty 'iommu_iotlb_gather' structure, should be a NOP. Elide the
CMD_SYNC when there is no invalidation to be performed.

Signed-off-by: Will Deacon <will@kernel.org>
---

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 2be11a11bb8bf..b7b3b0ff8ed6a 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -1977,6 +1977,9 @@ static void arm_smmu_tlb_inv_range(unsigned long iova, size_t size,
 		},
 	};
 
+	if (!size)
+		return;
+
 	if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
 		cmd.opcode	= CMDQ_OP_TLBI_NH_VA;
 		cmd.tlbi.asid	= smmu_domain->s1_cfg.cd.asid;