linux-kernel - [PATCH v5 3/6] iommu/qcom: Disable and reset context bank before programming

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Date:   Thu, 22 Jun 2023 11:27:39 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     agross@...nel.org
Cc:     andersson@...nel.org, luca@...tu.xyz, konrad.dybcio@...aro.org,
        dmitry.baryshkov@...aro.org, joro@...tes.org, will@...nel.org,
        robin.murphy@....com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        robdclark@...il.com, linux-arm-msm@...r.kernel.org,
        iommu@...ts.linux.dev, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, kernel@...labora.com
Subject: [PATCH v5 3/6] iommu/qcom: Disable and reset context bank before programming

Writing	the new	TTBRs, TCRs and MAIRs on a previously enabled
context bank may trigger a context fault, resulting in firmware
driven AP resets: change the domain initialization programming
sequence to disable the context bank(s) and to also clear the
related fault address (CB_FAR) and fault status (CB_FSR)
registers before writing new values to TTBR0/1, TCR/TCR2, MAIR0/1.

Fixes: 0ae349a0f33f ("iommu/qcom: Add qcom_iommu")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
---
 drivers/iommu/arm/arm-smmu/qcom_iommu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
index 8face57c4180..f1bd7c035db8 100644
--- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
+++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
@@ -273,6 +273,13 @@ static int qcom_iommu_init_domain(struct iommu_domain *domain,
 			ctx->secure_init = true;
 		}
 
+		/* Disable context bank before programming */
+		iommu_writel(ctx, ARM_SMMU_CB_SCTLR, 0);
+
+		/* Clear context bank fault address fault status registers */
+		iommu_writel(ctx, ARM_SMMU_CB_FAR, 0);
+		iommu_writel(ctx, ARM_SMMU_CB_FSR, ARM_SMMU_FSR_FAULT);
+
 		/* TTBRs */
 		iommu_writeq(ctx, ARM_SMMU_CB_TTBR0,
 				pgtbl_cfg.arm_lpae_s1_cfg.ttbr |
-- 
2.40.1