[PATCH v4 1/5] iommu/arm-smmu: Save additional information on context fault

[Will Deacon]

On Tue, Mar 04, 2025 at 11:56:47AM -0500, Connor Abbott wrote:
> This will be used by drm/msm for GPU page faults, replacing the manual
> register reading it does.
> 
> Signed-off-by: Connor Abbott <cwabbott0 at gmail.com>
> ---
>  drivers/iommu/arm/arm-smmu/arm-smmu-qcom-debug.c |  4 ++--
>  drivers/iommu/arm/arm-smmu/arm-smmu.c            | 27 +++++++++++++-----------
>  drivers/iommu/arm/arm-smmu/arm-smmu.h            |  5 ++++-
>  3 files changed, 21 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom-debug.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom-debug.c
> index 548783f3f8e89fd978367afa65c473002f66e2e7..ae4fdbbce6ba80440f539557a39866a932360d4e 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom-debug.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom-debug.c
> @@ -400,7 +400,7 @@ irqreturn_t qcom_smmu_context_fault(int irq, void *dev)
>  
>  	if (list_empty(&tbu_list)) {
>  		ret = report_iommu_fault(&smmu_domain->domain, NULL, cfi.iova,
> -					 cfi.fsynr & ARM_SMMU_CB_FSYNR0_WNR ? IOMMU_FAULT_WRITE : IOMMU_FAULT_READ);
> +					 cfi.fsynr0 & ARM_SMMU_CB_FSYNR0_WNR ? IOMMU_FAULT_WRITE : IOMMU_FAULT_READ);
>  
>  		if (ret == -ENOSYS)
>  			arm_smmu_print_context_fault_info(smmu, idx, &cfi);
> @@ -412,7 +412,7 @@ irqreturn_t qcom_smmu_context_fault(int irq, void *dev)
>  	phys_soft = ops->iova_to_phys(ops, cfi.iova);
>  
>  	tmp = report_iommu_fault(&smmu_domain->domain, NULL, cfi.iova,
> -				 cfi.fsynr & ARM_SMMU_CB_FSYNR0_WNR ? IOMMU_FAULT_WRITE : IOMMU_FAULT_READ);
> +				 cfi.fsynr0 & ARM_SMMU_CB_FSYNR0_WNR ? IOMMU_FAULT_WRITE : IOMMU_FAULT_READ);
>  	if (!tmp || tmp == -EBUSY) {
>  		ret = IRQ_HANDLED;
>  		resume = ARM_SMMU_RESUME_TERMINATE;
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index ade4684c14c9b2724a71e2457288dbfaf7562c83..a9213e0f1579d1e3be0bfba75eea1d5de23117de 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -409,9 +409,12 @@ void arm_smmu_read_context_fault_info(struct arm_smmu_device *smmu, int idx,
>  				      struct arm_smmu_context_fault_info *cfi)
>  {
>  	cfi->iova = arm_smmu_cb_readq(smmu, idx, ARM_SMMU_CB_FAR);
> +	cfi->ttbr0 = arm_smmu_cb_readq(smmu, idx, ARM_SMMU_CB_TTBR0);
>  	cfi->fsr = arm_smmu_cb_read(smmu, idx, ARM_SMMU_CB_FSR);
> -	cfi->fsynr = arm_smmu_cb_read(smmu, idx, ARM_SMMU_CB_FSYNR0);
> +	cfi->fsynr0 = arm_smmu_cb_read(smmu, idx, ARM_SMMU_CB_FSYNR0);
> +	cfi->fsynr1 = arm_smmu_cb_read(smmu, idx, ARM_SMMU_CB_FSYNR1);

We already have an implementation hook (->get_fault_info()) which the
qcom SMMU driver can override with qcom_adreno_smmu_get_fault_info().
That thing dumps these registers already so if we're moving that into
the core SMMU driver, let's get rid of the hook and move everybody over
rather than having it done in both places.

>  	cfi->cbfrsynra = arm_smmu_gr1_read(smmu, ARM_SMMU_GR1_CBFRSYNRA(idx));
> +	cfi->contextidr = arm_smmu_cb_read(smmu, idx, ARM_SMMU_CB_CONTEXTIDR);

I think the CONTEXTIDR register is stage-1 only, so we shouldn't dump
it for stage-2 domains.

Will