Subject: Re: [PATCH 4/7] iommu/arm-smmu: Add global/context fault implementation hooks

From: Thierry Reding <[email-masked]>
Date: Fri, 30 Aug 2019 13:17:07 +0200

On Thu, Aug 29, 2019 at 03:47:04PM -0700, Krishna Reddy wrote:
> Add global/context fault hooks to allow Nvidia SMMU implementation
> handle faults across multiple SMMUs.
> 
> Signed-off-by: Krishna Reddy <[email-masked]>
> ---
>  drivers/iommu/arm-smmu-nvidia.c | 127 ++++++++++++++++++++++++++++++++++++++++
>  drivers/iommu/arm-smmu.c        |   6 ++
>  drivers/iommu/arm-smmu.h        |   4 ++
>  3 files changed, 137 insertions(+)
> 
> diff --git a/drivers/iommu/arm-smmu-nvidia.c b/drivers/iommu/arm-smmu-nvidia.c
> index a429b2c..b2a3c49 100644
> --- a/drivers/iommu/arm-smmu-nvidia.c
> +++ b/drivers/iommu/arm-smmu-nvidia.c
> @@ -14,6 +14,10 @@
>  
>  #define NUM_SMMU_INSTANCES 3
>  
> +static irqreturn_t nsmmu_context_fault_inst(int irq,
> +					    struct arm_smmu_device *smmu,
> +					    int idx, int inst);

More of these signed integers that could be unsigned. Also why the need
to predeclare this? Can you not just put the definition of the function
up here?

> +
>  struct nvidia_smmu {
>  	struct arm_smmu_device	smmu;
>  	int			num_inst;
> @@ -87,12 +91,135 @@ static void nsmmu_tlb_sync(struct arm_smmu_device *smmu, int page,
>  		nsmmu_tlb_sync_wait(smmu, page, sync, status, i);
>  }
>  
> +static irqreturn_t nsmmu_global_fault_inst(int irq,
> +					       struct arm_smmu_device *smmu,
> +					       int inst)
> +{
> +	u32 gfsr, gfsynr0, gfsynr1, gfsynr2;
> +
> +	gfsr = readl_relaxed(nsmmu_page(smmu, inst, 0) + ARM_SMMU_GR0_sGFSR);
> +	gfsynr0 = readl_relaxed(nsmmu_page(smmu, inst, 0) +
> +				ARM_SMMU_GR0_sGFSYNR0);
> +	gfsynr1 = readl_relaxed(nsmmu_page(smmu, inst, 0) +
> +				ARM_SMMU_GR0_sGFSYNR1);
> +	gfsynr2 = readl_relaxed(nsmmu_page(smmu, inst, 0) +
> +				ARM_SMMU_GR0_sGFSYNR2);
> +
> +	if (!gfsr)
> +		return IRQ_NONE;
> +
> +	dev_err_ratelimited(smmu->dev,
> +		"Unexpected global fault, this could be serious\n");
> +	dev_err_ratelimited(smmu->dev,
> +		"\tGFSR 0x%08x, GFSYNR0 0x%08x, GFSYNR1 0x%08x, GFSYNR2 0x%08x\n",
> +		gfsr, gfsynr0, gfsynr1, gfsynr2);
> +
> +	writel_relaxed(gfsr, nsmmu_page(smmu, inst, 0) + ARM_SMMU_GR0_sGFSR);
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t nsmmu_global_fault(int irq, struct arm_smmu_device *smmu)
> +{
> +	int i;
> +	irqreturn_t irq_ret = IRQ_NONE;
> +
> +	/* Interrupt line is shared between global and context faults.
> +	 * Check for both type of interrupts on either fault handlers.
> +	 */
> +	for (i = 0; i < to_nsmmu(smmu)->num_inst; i++) {
> +		irq_ret = nsmmu_context_fault_inst(irq, smmu, 0, i);
> +		if (irq_ret == IRQ_HANDLED)
> +			return irq_ret;
> +	}
> +
> +	for (i = 0; i < to_nsmmu(smmu)->num_inst; i++) {
> +		irq_ret = nsmmu_global_fault_inst(irq, smmu, i);
> +		if (irq_ret == IRQ_HANDLED)
> +			return irq_ret;
> +	}
> +
> +	return irq_ret;
> +}
> +
> +static irqreturn_t nsmmu_context_fault_bank(int irq,
> +					    struct arm_smmu_device *smmu,
> +					    int idx, int inst)
> +{
> +	u32 fsr, fsynr, cbfrsynra;
> +	unsigned long iova;
> +
> +	fsr = arm_smmu_cb_read(smmu, idx, ARM_SMMU_CB_FSR);
> +	if (!(fsr & FSR_FAULT))
> +		return IRQ_NONE;
> +
> +	fsynr = readl_relaxed(nsmmu_page(smmu, inst, smmu->numpage + idx) +
> +			      ARM_SMMU_CB_FSYNR0);
> +	iova = readq_relaxed(nsmmu_page(smmu, inst, smmu->numpage + idx) +
> +			     ARM_SMMU_CB_FAR);
> +	cbfrsynra = readl_relaxed(nsmmu_page(smmu, inst, 1) +
> +				  ARM_SMMU_GR1_CBFRSYNRA(idx));
> +
> +	dev_err_ratelimited(smmu->dev,
> +	"Unhandled context fault: fsr=0x%x, iova=0x%08lx, fsynr=0x%x, cbfrsynra=0x%x, cb=%d\n",
> +			    fsr, iova, fsynr, cbfrsynra, idx);
> +
> +	writel_relaxed(fsr, nsmmu_page(smmu, inst, smmu->numpage + idx) +
> +			    ARM_SMMU_CB_FSR);
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t nsmmu_context_fault_inst(int irq,
> +					    struct arm_smmu_device *smmu,
> +					    int idx, int inst)
> +{
> +	irqreturn_t irq_ret = IRQ_NONE;
> +
> +	/* Interrupt line shared between global and all context faults.
> +	 * Check for faults across all contexts.
> +	 */
> +	for (idx = 0; idx < smmu->num_context_banks; idx++) {
> +		irq_ret = nsmmu_context_fault_bank(irq, smmu, idx, inst);
> +
> +		if (irq_ret == IRQ_HANDLED)
> +			break;
> +	}
> +
> +	return irq_ret;
> +}
> +
> +static irqreturn_t nsmmu_context_fault(int irq,
> +				       struct arm_smmu_device *smmu,
> +				       int cbndx)
> +{
> +	int i;
> +	irqreturn_t irq_ret = IRQ_NONE;
> +
> +	/* Interrupt line is shared between global and context faults.
> +	 * Check for both type of interrupts on either fault handlers.
> +	 */
> +	for (i = 0; i < to_nsmmu(smmu)->num_inst; i++) {
> +		irq_ret = nsmmu_global_fault_inst(irq, smmu, i);
> +		if (irq_ret == IRQ_HANDLED)
> +			return irq_ret;
> +	}
> +
> +	for (i = 0; i < to_nsmmu(smmu)->num_inst; i++) {
> +		irq_ret = nsmmu_context_fault_inst(irq, smmu, cbndx, i);
> +		if (irq_ret == IRQ_HANDLED)
> +			return irq_ret;
> +	}
> +
> +	return irq_ret;
> +}
> +
>  static const struct arm_smmu_impl nsmmu_impl = {
>  	.read_reg = nsmmu_read_reg,
>  	.write_reg = nsmmu_write_reg,
>  	.read_reg64 = nsmmu_read_reg64,
>  	.write_reg64 = nsmmu_write_reg64,
>  	.tlb_sync = nsmmu_tlb_sync,
> +	.global_fault = nsmmu_global_fault,
> +	.context_fault = nsmmu_context_fault,
>  };
>  
>  struct arm_smmu_device *nvidia_smmu_impl_init(struct arm_smmu_device *smmu)
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index f5454e71..9cc532d 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -454,6 +454,9 @@ static irqreturn_t arm_smmu_context_fault(int irq, void *dev)
>  	struct arm_smmu_device *smmu = smmu_domain->smmu;
>  	int idx = smmu_domain->cfg.cbndx;
>  
> +	if (smmu->impl->context_fault)
> +		return smmu->impl->context_fault(irq, smmu, idx);
> +

Same comment here...

>  	fsr = arm_smmu_cb_read(smmu, idx, ARM_SMMU_CB_FSR);
>  	if (!(fsr & FSR_FAULT))
>  		return IRQ_NONE;
> @@ -475,6 +478,9 @@ static irqreturn_t arm_smmu_global_fault(int irq, void *dev)
>  	u32 gfsr, gfsynr0, gfsynr1, gfsynr2;
>  	struct arm_smmu_device *smmu = dev;
>  
> +	if (smmu->impl->global_fault)
> +		return smmu->impl->global_fault(irq, smmu);

... and here about the extra level of indirection.

Thierry
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