linux-kernel - [PATCH 3/6] iommu/qcom: Properly reset the IOMMU context

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Message-Id: <20220527212901.29268-4-konrad.dybcio@somainline.org>
Date:   Fri, 27 May 2022 23:28:58 +0200
From:   Konrad Dybcio <konrad.dybcio@...ainline.org>
To:     ~postmarketos/upstreaming@...ts.sr.ht,
        linux-arm-msm@...r.kernel.org, bjorn.andersson@...aro.org,
        linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org
Cc:     martin.botka@...ainline.org,
        angelogioacchino.delregno@...ainline.org,
        marijn.suijten@...ainline.org, jamipkettunen@...ainline.org,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Rob Clark <robdclark@...il.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>, linux-kernel@...r.kernel.org
Subject: [PATCH 3/6] iommu/qcom: Properly reset the IOMMU context

From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>

To avoid context faults reset the context entirely on detach and
to ensure a fresh clean start also do a complete reset before
programming the context for domain initialization.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>
Signed-off-by: Marijn Suijten <marijn.suijten@...ainline.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@...ainline.org>
---
 drivers/iommu/arm/arm-smmu/qcom_iommu.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
index 75f353866c40..129e322f56a6 100644
--- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
+++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
@@ -223,6 +223,23 @@ static irqreturn_t qcom_iommu_fault(int irq, void *dev)
 	return IRQ_HANDLED;
 }
 
+static void qcom_iommu_reset_ctx(struct qcom_iommu_ctx *ctx)
+{
+	iommu_writel(ctx, ARM_SMMU_CB_FAR, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_FSR, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_S1_MAIR1, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_PAR, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_S1_MAIR0, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_SCTLR, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_TCR2, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_TCR, 0);
+	iommu_writeq(ctx, ARM_SMMU_CB_TTBR0, 0);
+	iommu_writeq(ctx, ARM_SMMU_CB_TTBR1, 0);
+
+	/* Should we issue a TLBSYNC there instead? */
+	wmb();
+}
+
 static int qcom_iommu_init_domain(struct iommu_domain *domain,
 				  struct qcom_iommu_dev *qcom_iommu,
 				  struct device *dev)
@@ -273,6 +290,8 @@ static int qcom_iommu_init_domain(struct iommu_domain *domain,
 			ctx->secure_init = true;
 		}
 
+		qcom_iommu_reset_ctx(ctx);
+
 		/* TCR */
 		iommu_writel(ctx, ARM_SMMU_CB_TCR2,
 				arm_smmu_lpae_tcr2(&pgtbl_cfg));
@@ -406,8 +425,8 @@ static void qcom_iommu_detach_dev(struct iommu_domain *domain, struct device *de
 	for (i = 0; i < fwspec->num_ids; i++) {
 		struct qcom_iommu_ctx *ctx = to_ctx(qcom_domain, fwspec->ids[i]);
 
-		/* Disable the context bank: */
-		iommu_writel(ctx, ARM_SMMU_CB_SCTLR, 0);
+		/* Disable and reset the context bank */
+		qcom_iommu_reset_ctx(ctx);
 
 		ctx->domain = NULL;
 	}
-- 
2.36.1