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

From: Bibek Kumar Patro
Date: Wed Nov 29 2023 - 07:04:48 EST




On 11/27/2023 9:37 PM, Dmitry Baryshkov wrote:
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

qsmmu->data has the actlrcfg/actlrcfg_gfx as well hence clubbed this change here as rightly suggested by Robin[1] on v2 revision.
Initially planned[2] for separate patch, but later clubbing it with actlr patch looked like a cleaner approach.
Would it be okay to keep it here? Or separate patch would be better?

[1]:https://lore.kernel.org/all/c75d107a-44cb-4df3-b583-13719df1f8be@xxxxxxx/
[2]:https://lore.kernel.org/all/9b406a7c-57b8-4b5f-8fbc-714560cce8cf@xxxxxxxxxxx/


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