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From: Robin Murphy <robin.murphy@arm.com>
To: kholk11@gmail.com, linux-arm-msm@vger.kernel.org
Cc: marijns95@gmail.com, agross@kernel.org, iommu@lists.linux-foundation.org
Subject: Re: [PATCH v4 4/7] iommu/qcom: Properly reset the IOMMU context
Date: Wed, 2 Oct 2019 12:29:47 +0100
Message-ID: <968a89c4-7928-21be-e8cb-22c571c9cc29@arm.com> (raw)
In-Reply-To: <20191001220205.6423-5-kholk11@gmail.com>

On 01/10/2019 23:02, kholk11@gmail.com wrote:
> From: AngeloGioacchino Del Regno <kholk11@gmail.com>
> 
> 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 <kholk11@gmail.com>
> ---
>   drivers/iommu/qcom_iommu.c | 23 +++++++++++++++++++++--
>   1 file changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/qcom_iommu.c b/drivers/iommu/qcom_iommu.c
> index c8957ec83b92..b4a38ef129e3 100644
> --- a/drivers/iommu/qcom_iommu.c
> +++ b/drivers/iommu/qcom_iommu.c
> @@ -220,6 +220,23 @@ 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? */

Unless there are outstanding TLB invalidations, it wouldn't achieve 
much. That said, doing a TBLIALL as part of the reset sequence *would* 
generally be a good idea.

Also, since the write to SCTLR affects the overall enable state of the 
context bank, it would be best to do that before touching anything else.

Robin.

> +	mb();
> +}
> +
>   static int qcom_iommu_init_domain(struct iommu_domain *domain,
>   				  struct qcom_iommu_dev *qcom_iommu,
>   				  struct iommu_fwspec *fwspec)
> @@ -267,6 +284,8 @@ 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,
>   				(pgtbl_cfg.arm_lpae_s1_cfg.tcr >> 32) |
> @@ -412,8 +431,8 @@ 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(fwspec, 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;
>   	}
> 
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Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-01 22:01 [PATCH v4 0/7] Add support for QCOM IOMMU v2 and 500 kholk11
2019-10-01 22:01 ` [PATCH v4 1/7] firmware: qcom: scm: Add function to set IOMMU pagetable addressing kholk11
2019-10-15 11:14   ` Joerg Roedel
2019-10-15 12:33     ` AngeloGioacchino Del Regno
2019-10-15 12:40       ` Joerg Roedel
2019-10-15 13:09         ` AngeloGioacchino Del Regno
2019-10-01 22:02 ` [PATCH v4 2/7] iommu/qcom: Use the asid read from device-tree if specified kholk11
2019-10-15 12:09   ` Robin Murphy
2019-10-15 13:06     ` AngeloGioacchino Del Regno
2019-10-01 22:02 ` [PATCH v4 3/7] iommu/qcom: Write TCR before TTBRs to fix ASID access behavior kholk11
2019-10-01 22:02 ` [PATCH v4 4/7] iommu/qcom: Properly reset the IOMMU context kholk11
2019-10-02 11:29   ` Robin Murphy [this message]
2019-10-01 22:02 ` [PATCH v4 5/7] iommu/qcom: Add support for AArch64 IOMMU pagetables kholk11
2019-10-01 22:02 ` [PATCH v4 6/7] iommu/qcom: Index contexts by asid number to allow asid 0 kholk11
2019-10-01 22:02 ` [PATCH v4 7/7] iommu/qcom: Add support for QCIOMMUv2 and QCIOMMU-500 secured contexts kholk11
2019-10-05  4:56 ` [PATCH v4 0/7] Add support for QCOM IOMMU v2 and 500 Bjorn Andersson
2019-10-05  9:32   ` AngeloGioacchino Del Regno

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