On Fri, Oct 30, 2020 at 02:53:09PM +0530, Sai Prakash Ranjan wrote:
> Add iommu domain attribute for using system cache aka last level
> cache by client drivers like GPU to set right attributes for caching
> the hardware pagetables into the system cache.
>
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ran...@codeaurora.org>
> ---
> drivers/iommu/arm/arm-smmu/arm-smmu.c | 17 +++++++++++++++++
> drivers/iommu/arm/arm-smmu/arm-smmu.h | 1 +
> include/linux/iommu.h | 1 +
> 3 files changed, 19 insertions(+)
>
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index b1cf8f0abc29..070d13f80c7e 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -789,6 +789,9 @@ static int arm_smmu_init_domain_context(struct
> iommu_domain *domain,
> if (smmu_domain->non_strict)
> pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;
>
> + if (smmu_domain->sys_cache)
> + pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_SYS_CACHE;
> +
> pgtbl_ops = alloc_io_pgtable_ops(fmt, &pgtbl_cfg, smmu_domain);
> if (!pgtbl_ops) {
> ret = -ENOMEM;
> @@ -1520,6 +1523,9 @@ static int arm_smmu_domain_get_attr(struct iommu_domain
> *domain,
> case DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE:
> *(int *)data = smmu_domain->non_strict;
> return 0;
> + case DOMAIN_ATTR_SYS_CACHE:
> + *((int *)data) = smmu_domain->sys_cache;
> + return 0;
> default:
> return -ENODEV;
> }
> @@ -1551,6 +1557,17 @@ static int arm_smmu_domain_set_attr(struct
> iommu_domain *domain,
> else
> smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
> break;
> + case DOMAIN_ATTR_SYS_CACHE:
> + if (smmu_domain->smmu) {
> + ret = -EPERM;
> + goto out_unlock;
> + }
> +
> + if (*((int *)data))
> + smmu_domain->sys_cache = true;
> + else
> + smmu_domain->sys_cache = false;
> + break;
> default:
> ret = -ENODEV;
> }
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> index 885840f3bec8..dfc44d806671 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> @@ -373,6 +373,7 @@ struct arm_smmu_domain {
> struct mutex init_mutex; /* Protects smmu pointer */
> spinlock_t cb_lock; /* Serialises ATS1* ops and
> TLB syncs */
> struct iommu_domain domain;
> + bool sys_cache;
> };
>
> struct arm_smmu_master_cfg {
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index b95a6f8db6ff..4f4bb9c6f8f6 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -118,6 +118,7 @@ enum iommu_attr {
> DOMAIN_ATTR_FSL_PAMUV1,
> DOMAIN_ATTR_NESTING, /* two stages of translation */
> DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE,
> + DOMAIN_ATTR_SYS_CACHE,
I think you're trying to make this look generic, but it's really not.
If we need to funnel io-pgtable quirks through domain attributes, then I
think we should be open about that and add something like
DOMAIN_ATTR_IO_PGTABLE_CFG which could take a struct of page-table
configuration data for the domain (this could just be quirks initially,
but maybe it's worth extending to take ias, oas and page size)
Will
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