Re: [PATCH 2/3] iommu/arm-smmu-v3: Make BTM optional for SVA

[Robin Murphy <robin.murphy@arm.com>]

On 2021-01-22 11:52, Jean-Philippe Brucker wrote:
> When BTM isn't supported by the SMMU, send invalidations on the
> command queue.
> 
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h     |  3 +++
>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 14 +++++++++++---
>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c     | 14 ++++++++++++++
>   3 files changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> index a6536c2b32d0..652d03ad8ae6 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -743,6 +743,9 @@ extern struct arm_smmu_ctx_desc quiet_cd;
>   int arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain, int ssid,
>   			    struct arm_smmu_ctx_desc *cd);
>   void arm_smmu_tlb_inv_asid(struct arm_smmu_device *smmu, u16 asid);
> +void arm_smmu_tlb_inv_range_asid(unsigned long iova, size_t size, int asid,
> +				 size_t granule, bool leaf,
> +				 struct arm_smmu_domain *smmu_domain);
>   bool arm_smmu_free_asid(struct arm_smmu_ctx_desc *cd);
>   int arm_smmu_atc_inv_domain(struct arm_smmu_domain *smmu_domain, int ssid,
>   			    unsigned long iova, size_t size);
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> index 642ce2c225b5..ad8cf62a8f83 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> @@ -16,6 +16,7 @@ struct arm_smmu_mmu_notifier {
>   	struct mmu_notifier		mn;
>   	struct arm_smmu_ctx_desc	*cd;
>   	bool				cleared;
> +	bool				tlb_inv_command;
>   	refcount_t			refs;
>   	struct list_head		list;
>   	struct arm_smmu_domain		*domain;
> @@ -182,9 +183,13 @@ static void arm_smmu_mm_invalidate_range(struct mmu_notifier *mn,
>   					 unsigned long start, unsigned long end)
>   {
>   	struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn);
> +	struct arm_smmu_domain *smmu_domain = smmu_mn->domain;
> +	size_t size = end - start + 1;
>   
> -	arm_smmu_atc_inv_domain(smmu_mn->domain, mm->pasid, start,
> -				end - start + 1);
> +	if (smmu_mn->tlb_inv_command)

Since we're going to be drilling down to smmu_domain->smmu->features in 
the invalidate call anyway, perhaps we could just test for BTM directly 
here?

Obviously that also proves my previous comment involved a reading 
comprehension failure and too much haste, so should be discounted. Sorry 
about that :)

Robin.

> +		arm_smmu_tlb_inv_range_asid(start, size, smmu_mn->cd->asid,
> +					    PAGE_SIZE, false, smmu_domain);
> +	arm_smmu_atc_inv_domain(smmu_domain, mm->pasid, start, size);
>   }
>   
>   static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
> @@ -253,6 +258,9 @@ arm_smmu_mmu_notifier_get(struct arm_smmu_domain *smmu_domain,
>   	smmu_mn->domain = smmu_domain;
>   	smmu_mn->mn.ops = &arm_smmu_mmu_notifier_ops;
>   
> +	if (!(smmu_domain->smmu->features & ARM_SMMU_FEAT_BTM))
> +		smmu_mn->tlb_inv_command = true;
> +
>   	ret = mmu_notifier_register(&smmu_mn->mn, mm);
>   	if (ret) {
>   		kfree(smmu_mn);
> @@ -404,7 +412,7 @@ bool arm_smmu_sva_supported(struct arm_smmu_device *smmu)
>   	unsigned long reg, fld;
>   	unsigned long oas;
>   	unsigned long asid_bits;
> -	u32 feat_mask = ARM_SMMU_FEAT_BTM | ARM_SMMU_FEAT_COHERENCY;
> +	u32 feat_mask = ARM_SMMU_FEAT_COHERENCY;
>   
>   	if (vabits_actual == 52)
>   		feat_mask |= ARM_SMMU_FEAT_VAX;
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index a27b074d5c0c..db545834493b 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2018,6 +2018,20 @@ static void arm_smmu_tlb_inv_range_domain(unsigned long iova, size_t size,
>   	arm_smmu_atc_inv_domain(smmu_domain, 0, iova, size);
>   }
>   
> +void arm_smmu_tlb_inv_range_asid(unsigned long iova, size_t size, int asid,
> +				 size_t granule, bool leaf,
> +				 struct arm_smmu_domain *smmu_domain)
> +{
> +	struct arm_smmu_cmdq_ent cmd = {
> +		.opcode	= CMDQ_OP_TLBI_NH_VA,
> +		.tlbi = {
> +			.asid	= asid,
> +			.leaf	= leaf,
> +		},
> +	};
> +	arm_smmu_tlb_inv_range(&cmd, iova, size, granule, smmu_domain);
> +}
> +
>   static void arm_smmu_tlb_inv_page_nosync(struct iommu_iotlb_gather *gather,
>   					 unsigned long iova, size_t granule,
>   					 void *cookie)
> 
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