On Thu, Jan 2, 2020 at 3:02 AM Sharat Masetty <smasetty@xxxxxxxxxxxxxx> wrote:
>
> From: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
>
> Add iommu domain attribute for using system cache aka last level
> cache on QCOM SoCs by client drivers like GPU to set right
> attributes for caching the hardware pagetables into the system cache.
>
> Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
> Co-developed-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
> ---
> drivers/iommu/arm-smmu-qcom.c | 10 ++++++++++
> drivers/iommu/arm-smmu.c | 14 ++++++++++++++
> drivers/iommu/arm-smmu.h | 1 +
> include/linux/iommu.h | 1 +
> 4 files changed, 26 insertions(+)
>
> diff --git a/drivers/iommu/arm-smmu-qcom.c b/drivers/iommu/arm-smmu-qcom.c
> index 24c071c..d1d22df 100644
> --- a/drivers/iommu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm-smmu-qcom.c
> @@ -30,7 +30,17 @@ static int qcom_sdm845_smmu500_reset(struct arm_smmu_device *smmu)
> return ret;
> }
>
> +static int qcom_smmu_init_context(struct arm_smmu_domain *smmu_domain,
> + struct io_pgtable_cfg *pgtbl_cfg)
> +{
> + if (smmu_domain->sys_cache)
> + pgtbl_cfg->coherent_walk = false;
just curious, does coherent walk not work with sys-cache, or is it
just that it is kind of pointless (given that, afaiu, the pagetables
can be cached by the system cache)?
> +
> + return 0;
> +}
> +
> static const struct arm_smmu_impl qcom_smmu_impl = {
> + .init_context = qcom_smmu_init_context,
> .reset = qcom_sdm845_smmu500_reset,
> };
>
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 4f7e0c0..055b548 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -1466,6 +1466,9 @@ static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
> case DOMAIN_ATTR_NESTING:
> *(int *)data = (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED);
> return 0;
> + case DOMAIN_ATTR_QCOM_SYS_CACHE:
> + *((int *)data) = smmu_domain->sys_cache;
> + return 0;
> default:
> return -ENODEV;
> }
> @@ -1506,6 +1509,17 @@ static int arm_smmu_domain_set_attr(struct iommu_domain *domain,
> else
> smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
> break;
> + case DOMAIN_ATTR_QCOM_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-smmu.h b/drivers/iommu/arm-smmu.h
> index f57cdbe..8aeaaf0 100644
> --- a/drivers/iommu/arm-smmu.h
> +++ b/drivers/iommu/arm-smmu.h
> @@ -322,6 +322,7 @@ 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;
> };
>
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 0c60e75..bd61c60 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -127,6 +127,7 @@ enum iommu_attr {
> DOMAIN_ATTR_FSL_PAMUV1,
> DOMAIN_ATTR_NESTING, /* two stages of translation */
> DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE,
> + DOMAIN_ATTR_QCOM_SYS_CACHE,
Given that IOMMU_QCOM_SYS_CACHE was renamed to IOMMU_SYS_CACHE_ONLY, I
wonder if this domain attr should simply be DOMAIN_ATTR_SYS_CACHE?
But that said, the function of this domain attr seems to simply be to
disable coherent walk.. I wonder if naming the domain attr after what
it does would make more sense?
BR,
-R
> DOMAIN_ATTR_MAX,
> };
>
> --
> 1.9.1
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