Re: [PATCH v3 1/4] iommu/arm-smmu: introduction of ACTLR for custom prefetcher settings

[Dmitry Baryshkov]

On Mon, 27 Nov 2023 at 16:54, Bibek Kumar Patro
<quic_bibekkum@xxxxxxxxxxx> wrote:
>
> Currently in Qualcomm  SoCs the default prefetch is set to 1 which allows
> the TLB to fetch just the next page table. MMU-500 features ACTLR
> register which is implementation defined and is used for Qualcomm SoCs
> to have a prefetch setting of 1/3/7/15 enabling TLB to prefetch
> the next set of page tables accordingly allowing for faster translations.
>
> ACTLR value is unique for each SMR (Stream matching register) and stored
> in a pre-populated table. This value is set to the register during
> context bank initialisation.
>
> Signed-off-by: Bibek Kumar Patro <quic_bibekkum@xxxxxxxxxxx>
>
> ---
>  drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 56 +++++++++++++++++++++-
>  drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h |  6 ++-
>  drivers/iommu/arm/arm-smmu/arm-smmu.c      |  5 +-
>  drivers/iommu/arm/arm-smmu/arm-smmu.h      |  5 ++
>  4 files changed, 68 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> index 7f52ac67495f..4a38cae29be2 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> @@ -14,6 +14,12 @@
>
>  #define QCOM_DUMMY_VAL -1
>
> +struct actlr_config {
> +       u16 sid;
> +       u16 mask;
> +       u32 actlr;
> +};
> +
>  static struct qcom_smmu *to_qcom_smmu(struct arm_smmu_device *smmu)
>  {
>         return container_of(smmu, struct qcom_smmu, smmu);
> @@ -205,10 +211,40 @@ static bool qcom_adreno_can_do_ttbr1(struct arm_smmu_device *smmu)
>         return true;
>  }
>
> +static void arm_smmu_set_actlr(struct device *dev, struct arm_smmu_device *smmu, int cbndx,
> +               const struct actlr_config *actlrcfg, size_t actlrcfg_size)
> +{
> +       struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> +       struct arm_smmu_master_cfg *cfg = dev_iommu_priv_get(dev);
> +       struct arm_smmu_smr *smr;
> +       int i;
> +       int j;
> +       u16 id;
> +       u16 mask;
> +       int idx;
> +
> +       for (i = 0; i < actlrcfg_size; ++i) {
> +               id = (actlrcfg + i)->sid;
> +               mask = (actlrcfg + i)->mask;
> +
> +               for_each_cfg_sme(cfg, fwspec, j, idx) {
> +                       smr = &smmu->smrs[idx];
> +                       if (smr_is_subset(*smr, id, mask))
> +                               arm_smmu_cb_write(smmu, cbndx, ARM_SMMU_CB_ACTLR,
> +                                               (actlrcfg + i)->actlr);
> +               }
> +       }
> +}
> +
>  static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
>                 struct io_pgtable_cfg *pgtbl_cfg, struct device *dev)
>  {
>         struct adreno_smmu_priv *priv;
> +       struct arm_smmu_device *smmu = smmu_domain->smmu;
> +       struct qcom_smmu *qsmmu = to_qcom_smmu(smmu);
> +       const struct actlr_config *actlrcfg;
> +       size_t actlrcfg_size;
> +       int cbndx = smmu_domain->cfg.cbndx;
>
>         smmu_domain->cfg.flush_walk_prefer_tlbiasid = true;
>
> @@ -238,6 +274,12 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
>         priv->set_stall = qcom_adreno_smmu_set_stall;
>         priv->resume_translation = qcom_adreno_smmu_resume_translation;
>
> +       if (qsmmu->data->actlrcfg_gfx) {
> +               actlrcfg = qsmmu->data->actlrcfg_gfx;
> +               actlrcfg_size = qsmmu->data->actlrcfg_gfx_size;
> +               arm_smmu_set_actlr(dev, smmu, cbndx, actlrcfg, actlrcfg_size);
> +       }
> +
>         return 0;
>  }
>
> @@ -263,6 +305,18 @@ static const struct of_device_id qcom_smmu_client_of_match[] __maybe_unused = {
>  static int qcom_smmu_init_context(struct arm_smmu_domain *smmu_domain,
>                 struct io_pgtable_cfg *pgtbl_cfg, struct device *dev)
>  {
> +       struct arm_smmu_device *smmu = smmu_domain->smmu;
> +       struct qcom_smmu *qsmmu = to_qcom_smmu(smmu);
> +       const struct actlr_config *actlrcfg;
> +       size_t actlrcfg_size;
> +       int cbndx = smmu_domain->cfg.cbndx;
> +
> +       if (qsmmu->data->actlrcfg) {
> +               actlrcfg = qsmmu->data->actlrcfg;
> +               actlrcfg_size = qsmmu->data->actlrcfg_size;
> +               arm_smmu_set_actlr(dev, smmu, cbndx, actlrcfg, actlrcfg_size);
> +       }
> +
>         smmu_domain->cfg.flush_walk_prefer_tlbiasid = true;
>
>         return 0;
> @@ -464,7 +518,7 @@ static struct arm_smmu_device *qcom_smmu_create(struct arm_smmu_device *smmu,
>                 return ERR_PTR(-ENOMEM);
>
>         qsmmu->smmu.impl = impl;
> -       qsmmu->cfg = data->cfg;
> +       qsmmu->data = data;

This should go to a separate commit. It is not related to ACTLR support

>
>         return &qsmmu->smmu;
>  }
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
> index 593910567b88..138fc57f7b0d 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
> @@ -8,7 +8,7 @@
>
>  struct qcom_smmu {
>         struct arm_smmu_device smmu;
> -       const struct qcom_smmu_config *cfg;
> +       const struct qcom_smmu_match_data *data;
>         bool bypass_quirk;
>         u8 bypass_cbndx;
>         u32 stall_enabled;
> @@ -25,6 +25,10 @@ struct qcom_smmu_config {
>  };
>
>  struct qcom_smmu_match_data {
> +       const struct actlr_config *actlrcfg;
> +       size_t actlrcfg_size;
> +       const struct actlr_config *actlrcfg_gfx;
> +       size_t actlrcfg_gfx_size;
>         const struct qcom_smmu_config *cfg;
>         const struct arm_smmu_impl *impl;
>         const struct arm_smmu_impl *adreno_impl;
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index d6d1a2a55cc0..8e4faf015286 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -990,9 +990,10 @@ static int arm_smmu_find_sme(struct arm_smmu_device *smmu, u16 id, u16 mask)
>                  * expect simply identical entries for this case, but there's
>                  * no harm in accommodating the generalisation.
>                  */
> -               if ((mask & smrs[i].mask) == mask &&
> -                   !((id ^ smrs[i].id) & ~smrs[i].mask))
> +
> +               if (smr_is_subset(smrs[i], id, mask))
>                         return i;
> +
>                 /*
>                  * If the new entry has any other overlap with an existing one,
>                  * though, then there always exists at least one stream ID
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> index 703fd5817ec1..b1638bbc41d4 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> @@ -501,6 +501,11 @@ static inline void arm_smmu_writeq(struct arm_smmu_device *smmu, int page,
>                 writeq_relaxed(val, arm_smmu_page(smmu, page) + offset);
>  }
>
> +static inline bool smr_is_subset(struct arm_smmu_smr smrs, u16 id, u16 mask)

A pointer to the struct, please

> +{
> +       return (mask & smrs.mask) == mask && !((id ^ smrs.id) & ~smrs.mask);
> +}
> +
>  #define ARM_SMMU_GR0           0
>  #define ARM_SMMU_GR1           1
>  #define ARM_SMMU_CB(s, n)      ((s)->numpage + (n))
> --
> 2.17.1
>


-- 
With best wishes
Dmitry