From aea2037e0d3e23c3be1498feae29f71ca997d9e6 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 29 Jul 2016 11:15:37 +0100 Subject: [PATCH] iommu/arm-smmu: Fix CMDQ error handling In the unlikely event of a global command queue error, the ARM SMMUv3 driver attempts to convert the problematic command into a CMD_SYNC and resume the command queue. Unfortunately, this code is pretty badly broken: 1. It uses the index into the error string table as the CMDQ index, so we probably read the wrong entry out of the queue 2. The arguments to queue_write are the wrong way round, so we end up writing from the queue onto the stack. These happily cancel out, so the kernel is likely to stay alive, but the command queue will probably fault again when we resume. This patch fixes the error handling code to use the correct queue index and write back the CMD_SYNC to the faulting entry. Cc: Fixes: 48ec83bcbcf5 ("iommu/arm-smmu: Add initial driver support for ARM SMMUv3 devices") Reported-by: Diwakar Subraveti Signed-off-by: Will Deacon --- drivers/iommu/arm-smmu-v3.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index ce801170d5f2..330623f8e344 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -879,7 +879,7 @@ static void arm_smmu_cmdq_skip_err(struct arm_smmu_device *smmu) * We may have concurrent producers, so we need to be careful * not to touch any of the shadow cmdq state. */ - queue_read(cmd, Q_ENT(q, idx), q->ent_dwords); + queue_read(cmd, Q_ENT(q, cons), q->ent_dwords); dev_err(smmu->dev, "skipping command in error state:\n"); for (i = 0; i < ARRAY_SIZE(cmd); ++i) dev_err(smmu->dev, "\t0x%016llx\n", (unsigned long long)cmd[i]); @@ -890,7 +890,7 @@ static void arm_smmu_cmdq_skip_err(struct arm_smmu_device *smmu) return; } - queue_write(cmd, Q_ENT(q, idx), q->ent_dwords); + queue_write(Q_ENT(q, cons), cmd, q->ent_dwords); } static void arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu,