Re: [PATCH] iommu/io-pgtable: Remove tlb_flush_leaf

On Wed, Nov 25, 2020 at 06:24:13PM +0000, Robin Murphy wrote:

On 2020-11-25 17:29, Robin Murphy wrote:

...

The only user of tlb_flush_leaf is a particularly hairy corner of the Arm short-descriptor code, which wants a synchronous invalidation to minimise the races inherent in trying to split a large page mapping. This is already far enough into "here be dragons" territory that no sensible caller should ever hit it, and thus it really doesn't need optimising. Although using tlb_flush_walk there may technically be more heavyweight than needed, it does the job and saves everyone else having to carry around useless baggage.

Signed-off-by: Robin Murphy robin.murphy@arm.com

Reviewing the Mediatek TLB optimisation patches just left me thinking "why do we even have this?"... Panfrost folks, this has zero functional impact to you, merely wants an ack for straying outside drivers/iommu.

Oops, same goes for MSM folks too - I honestly failed to even notice that some of the "msm_iommu" code actually lives in DRM. Maybe the fancy editor makes life *too* easy and I should go back to grep and vim and having to pay attention to paths... :)

Not a problem - having io-pgtable outside of drivers/iommu is new to most of us too.

drm/msm LGTM.

Jordan

Robin.

...

drivers/gpu/drm/msm/msm_iommu.c | 1 - drivers/gpu/drm/panfrost/panfrost_mmu.c | 7 ------ drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 7 ------ drivers/iommu/arm/arm-smmu/arm-smmu.c | 25 +++------------------ drivers/iommu/arm/arm-smmu/qcom_iommu.c | 8 ------- drivers/iommu/io-pgtable-arm-v7s.c | 3 +-- drivers/iommu/io-pgtable-arm.c | 1 - drivers/iommu/ipmmu-vmsa.c | 1 - drivers/iommu/msm_iommu.c | 7 ------ drivers/iommu/mtk_iommu.c | 1 - include/linux/io-pgtable.h | 11 --------- 11 files changed, 4 insertions(+), 68 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c index 22ac7c692a81..50d881794758 100644 --- a/drivers/gpu/drm/msm/msm_iommu.c +++ b/drivers/gpu/drm/msm/msm_iommu.c @@ -139,7 +139,6 @@ static void msm_iommu_tlb_add_page(struct iommu_iotlb_gather *gather, static const struct iommu_flush_ops null_tlb_ops = { .tlb_flush_all = msm_iommu_tlb_flush_all, .tlb_flush_walk = msm_iommu_tlb_flush_walk,

• .tlb_flush_leaf = msm_iommu_tlb_flush_walk, .tlb_add_page = msm_iommu_tlb_add_page,

};

diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c index 776448c527ea..c186914cc4f9 100644 --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c @@ -347,16 +347,9 @@ static void mmu_tlb_flush_walk(unsigned long iova, size_t size, size_t granule, mmu_tlb_sync_context(cookie); }

-static void mmu_tlb_flush_leaf(unsigned long iova, size_t size, size_t granule,

• 	       void *cookie)
  

-{

• mmu_tlb_sync_context(cookie);

-}

static const struct iommu_flush_ops mmu_tlb_ops = { .tlb_flush_all = mmu_tlb_inv_context_s1, .tlb_flush_walk = mmu_tlb_flush_walk,

• .tlb_flush_leaf = mmu_tlb_flush_leaf,

};

int panfrost_mmu_pgtable_alloc(struct panfrost_file_priv *priv) 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 e634bbe60573..fb684a393118 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -1741,16 +1741,9 @@ static void arm_smmu_tlb_inv_walk(unsigned long iova, size_t size, arm_smmu_tlb_inv_range(iova, size, granule, false, cookie); }

-static void arm_smmu_tlb_inv_leaf(unsigned long iova, size_t size,

• 		  size_t granule, void *cookie)
  

-{

• arm_smmu_tlb_inv_range(iova, size, granule, true, cookie);

-}

static const struct iommu_flush_ops arm_smmu_flush_ops = { .tlb_flush_all = arm_smmu_tlb_inv_context, .tlb_flush_walk = arm_smmu_tlb_inv_walk,

• .tlb_flush_leaf = arm_smmu_tlb_inv_leaf, .tlb_add_page = arm_smmu_tlb_inv_page_nosync,

};

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c index dad7fa86fbd4..0b8c59922a2b 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c @@ -333,14 +333,6 @@ static void arm_smmu_tlb_inv_walk_s1(unsigned long iova, size_t size, arm_smmu_tlb_sync_context(cookie); }

-static void arm_smmu_tlb_inv_leaf_s1(unsigned long iova, size_t size,

• 		     size_t granule, void *cookie)
  

-{

• arm_smmu_tlb_inv_range_s1(iova, size, granule, cookie,

• 		  ARM_SMMU_CB_S1_TLBIVAL);
  

• arm_smmu_tlb_sync_context(cookie);

-}

static void arm_smmu_tlb_add_page_s1(struct iommu_iotlb_gather *gather, unsigned long iova, size_t granule, void *cookie) @@ -357,14 +349,6 @@ static void arm_smmu_tlb_inv_walk_s2(unsigned long iova, size_t size, arm_smmu_tlb_sync_context(cookie); }

-static void arm_smmu_tlb_inv_leaf_s2(unsigned long iova, size_t size,

• 		     size_t granule, void *cookie)
  

-{

• arm_smmu_tlb_inv_range_s2(iova, size, granule, cookie,

• 		  ARM_SMMU_CB_S2_TLBIIPAS2L);
  

• arm_smmu_tlb_sync_context(cookie);

-}

static void arm_smmu_tlb_add_page_s2(struct iommu_iotlb_gather *gather, unsigned long iova, size_t granule, void *cookie) @@ -373,8 +357,8 @@ static void arm_smmu_tlb_add_page_s2(struct iommu_iotlb_gather *gather, ARM_SMMU_CB_S2_TLBIIPAS2L); }

-static void arm_smmu_tlb_inv_any_s2_v1(unsigned long iova, size_t size,

• 		       size_t granule, void *cookie)
  

+static void arm_smmu_tlb_inv_walk_s2_v1(unsigned long iova, size_t size,

• 			size_t granule, void *cookie)
  

{ arm_smmu_tlb_inv_context_s2(cookie); } @@ -401,21 +385,18 @@ static void arm_smmu_tlb_add_page_s2_v1(struct iommu_iotlb_gather *gather, static const struct iommu_flush_ops arm_smmu_s1_tlb_ops = { .tlb_flush_all = arm_smmu_tlb_inv_context_s1, .tlb_flush_walk = arm_smmu_tlb_inv_walk_s1,

• .tlb_flush_leaf = arm_smmu_tlb_inv_leaf_s1, .tlb_add_page = arm_smmu_tlb_add_page_s1,

};

static const struct iommu_flush_ops arm_smmu_s2_tlb_ops_v2 = { .tlb_flush_all = arm_smmu_tlb_inv_context_s2, .tlb_flush_walk = arm_smmu_tlb_inv_walk_s2,

• .tlb_flush_leaf = arm_smmu_tlb_inv_leaf_s2, .tlb_add_page = arm_smmu_tlb_add_page_s2,

};

static const struct iommu_flush_ops arm_smmu_s2_tlb_ops_v1 = { .tlb_flush_all = arm_smmu_tlb_inv_context_s2,

• .tlb_flush_walk = arm_smmu_tlb_inv_any_s2_v1,
• .tlb_flush_leaf = arm_smmu_tlb_inv_any_s2_v1,

• .tlb_flush_walk = arm_smmu_tlb_inv_walk_s2_v1, .tlb_add_page = arm_smmu_tlb_add_page_s2_v1,

};

diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c index b30d6c966e2c..7f280c8d5c53 100644 --- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c +++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c @@ -185,13 +185,6 @@ static void qcom_iommu_tlb_flush_walk(unsigned long iova, size_t size, qcom_iommu_tlb_sync(cookie); }

-static void qcom_iommu_tlb_flush_leaf(unsigned long iova, size_t size,

• 		      size_t granule, void *cookie)
  

-{

• qcom_iommu_tlb_inv_range_nosync(iova, size, granule, true, cookie);
• qcom_iommu_tlb_sync(cookie);

-}

static void qcom_iommu_tlb_add_page(struct iommu_iotlb_gather *gather, unsigned long iova, size_t granule, void *cookie) @@ -202,7 +195,6 @@ static void qcom_iommu_tlb_add_page(struct iommu_iotlb_gather *gather, static const struct iommu_flush_ops qcom_flush_ops = { .tlb_flush_all = qcom_iommu_tlb_inv_context, .tlb_flush_walk = qcom_iommu_tlb_flush_walk,

• .tlb_flush_leaf = qcom_iommu_tlb_flush_leaf, .tlb_add_page = qcom_iommu_tlb_add_page,

};

diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c index a688f22cbe3b..3cf72c100add 100644 --- a/drivers/iommu/io-pgtable-arm-v7s.c +++ b/drivers/iommu/io-pgtable-arm-v7s.c @@ -584,7 +584,7 @@ static arm_v7s_iopte arm_v7s_split_cont(struct arm_v7s_io_pgtable *data, __arm_v7s_pte_sync(ptep, ARM_V7S_CONT_PAGES, &iop->cfg);

size *= ARM_V7S_CONT_PAGES;

• io_pgtable_tlb_flush_leaf(iop, iova, size, size);

• io_pgtable_tlb_flush_walk(iop, iova, size, size); return pte;

}

@@ -866,7 +866,6 @@ static void __init dummy_tlb_add_page(struct iommu_iotlb_gather *gather, static const struct iommu_flush_ops dummy_tlb_ops __initconst = { .tlb_flush_all = dummy_tlb_flush_all, .tlb_flush_walk = dummy_tlb_flush,

• .tlb_flush_leaf = dummy_tlb_flush, .tlb_add_page = dummy_tlb_add_page,

};

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index a7a9bc08dcd1..938830e07dcf 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -1079,7 +1079,6 @@ static void __init dummy_tlb_add_page(struct iommu_iotlb_gather *gather, static const struct iommu_flush_ops dummy_tlb_ops __initconst = { .tlb_flush_all = dummy_tlb_flush_all, .tlb_flush_walk = dummy_tlb_flush,

• .tlb_flush_leaf = dummy_tlb_flush, .tlb_add_page = dummy_tlb_add_page,

};

diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c index 0f18abda0e20..d71f10257f15 100644 --- a/drivers/iommu/ipmmu-vmsa.c +++ b/drivers/iommu/ipmmu-vmsa.c @@ -325,7 +325,6 @@ static void ipmmu_tlb_flush(unsigned long iova, size_t size, static const struct iommu_flush_ops ipmmu_flush_ops = { .tlb_flush_all = ipmmu_tlb_flush_all, .tlb_flush_walk = ipmmu_tlb_flush,

• .tlb_flush_leaf = ipmmu_tlb_flush,

};

/* ----------------------------------------------------------------------------- diff --git a/drivers/iommu/msm_iommu.c b/drivers/iommu/msm_iommu.c index 3615cd6241c4..040e85f70861 100644 --- a/drivers/iommu/msm_iommu.c +++ b/drivers/iommu/msm_iommu.c @@ -174,12 +174,6 @@ static void __flush_iotlb_walk(unsigned long iova, size_t size, __flush_iotlb_range(iova, size, granule, false, cookie); }

-static void __flush_iotlb_leaf(unsigned long iova, size_t size,

• 	       size_t granule, void *cookie)
  

-{

• __flush_iotlb_range(iova, size, granule, true, cookie);

-}

static void __flush_iotlb_page(struct iommu_iotlb_gather *gather, unsigned long iova, size_t granule, void *cookie) { @@ -189,7 +183,6 @@ static void __flush_iotlb_page(struct iommu_iotlb_gather *gather, static const struct iommu_flush_ops msm_iommu_flush_ops = { .tlb_flush_all = __flush_iotlb, .tlb_flush_walk = __flush_iotlb_walk,

• .tlb_flush_leaf = __flush_iotlb_leaf, .tlb_add_page = __flush_iotlb_page,

};

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c index c072cee532c2..8e56cec532e7 100644 --- a/drivers/iommu/mtk_iommu.c +++ b/drivers/iommu/mtk_iommu.c @@ -240,7 +240,6 @@ static void mtk_iommu_tlb_flush_page_nosync(struct iommu_iotlb_gather *gather, static const struct iommu_flush_ops mtk_iommu_flush_ops = { .tlb_flush_all = mtk_iommu_tlb_flush_all, .tlb_flush_walk = mtk_iommu_tlb_flush_range_sync,

• .tlb_flush_leaf = mtk_iommu_tlb_flush_range_sync, .tlb_add_page = mtk_iommu_tlb_flush_page_nosync,

};

diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h index 4cde111e425b..ec9fae37c0e4 100644 --- a/include/linux/io-pgtable.h +++ b/include/linux/io-pgtable.h @@ -25,8 +25,6 @@ enum io_pgtable_fmt {

• @tlb_flush_walk: Synchronously invalidate all intermediate TLB state

•              (sometimes referred to as the "walk cache") for a virtual
  

•              address range.
  

• • @tlb_flush_leaf: Synchronously invalidate all leaf TLB state for a virtual

• •              address range.
    

  • @tlb_add_page: Optional callback to queue up leaf TLB invalidation for a

  •              single page.  IOMMUs that cannot batch TLB invalidation
    

  •              operations efficiently will typically issue them here, but
    

@@ -40,8 +38,6 @@ struct iommu_flush_ops { void (*tlb_flush_all)(void *cookie); void (*tlb_flush_walk)(unsigned long iova, size_t size, size_t granule, void *cookie);

• void (*tlb_flush_leaf)(unsigned long iova, size_t size, size_t granule,

• 	       void *cookie);
  

  void (*tlb_add_page)(struct iommu_iotlb_gather *gather, unsigned long iova, size_t granule, void *cookie);

}; @@ -220,13 +216,6 @@ io_pgtable_tlb_flush_walk(struct io_pgtable *iop, unsigned long iova, iop->cfg.tlb->tlb_flush_walk(iova, size, granule, iop->cookie); }

-static inline void -io_pgtable_tlb_flush_leaf(struct io_pgtable *iop, unsigned long iova,

• 	  size_t size, size_t granule)
  

-{

• iop->cfg.tlb->tlb_flush_leaf(iova, size, granule, iop->cookie);

-}

static inline void io_pgtable_tlb_add_page(struct io_pgtable *iop, struct iommu_iotlb_gather * gather, unsigned long iova, -- 2.17.1

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