Messages in this thread | | | Subject | Re: [PATCH v3 4/6] iommu/io-pgtable-arm: add support for non-strict mode | From | Robin Murphy <> | Date | Thu, 26 Jul 2018 15:35:59 +0100 |
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On 2018-07-26 8:20 AM, Leizhen (ThunderTown) wrote: > On 2018/7/25 6:25, Robin Murphy wrote: >> On 2018-07-12 7:18 AM, Zhen Lei wrote: >>> To support the non-strict mode, now we only tlbi and sync for the strict >>> mode. But for the non-leaf case, always follow strict mode. >>> >>> Use the lowest bit of the iova parameter to pass the strict mode: >>> 0, IOMMU_STRICT; >>> 1, IOMMU_NON_STRICT; >>> Treat 0 as IOMMU_STRICT, so that the unmap operation can compatible with >>> other IOMMUs which still use strict mode. >>> >>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> >>> --- >>> drivers/iommu/io-pgtable-arm.c | 23 ++++++++++++++--------- >>> 1 file changed, 14 insertions(+), 9 deletions(-) >>> >>> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c >>> index 010a254..9234db3 100644 >>> --- a/drivers/iommu/io-pgtable-arm.c >>> +++ b/drivers/iommu/io-pgtable-arm.c >>> @@ -292,7 +292,7 @@ static void __arm_lpae_set_pte(arm_lpae_iopte *ptep, arm_lpae_iopte pte, >>> static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, >>> unsigned long iova, size_t size, int lvl, >>> - arm_lpae_iopte *ptep); >>> + arm_lpae_iopte *ptep, int strict); >>> static void __arm_lpae_init_pte(struct arm_lpae_io_pgtable *data, >>> phys_addr_t paddr, arm_lpae_iopte prot, >>> @@ -334,7 +334,7 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable *data, >>> size_t sz = ARM_LPAE_BLOCK_SIZE(lvl, data); >>> tblp = ptep - ARM_LPAE_LVL_IDX(iova, lvl, data); >>> - if (WARN_ON(__arm_lpae_unmap(data, iova, sz, lvl, tblp) != sz)) >>> + if (WARN_ON(__arm_lpae_unmap(data, iova, sz, lvl, tblp, IOMMU_STRICT) != sz)) >>> return -EINVAL; >>> } >>> @@ -531,7 +531,7 @@ static void arm_lpae_free_pgtable(struct io_pgtable *iop) >>> static size_t arm_lpae_split_blk_unmap(struct arm_lpae_io_pgtable *data, >>> unsigned long iova, size_t size, >>> arm_lpae_iopte blk_pte, int lvl, >>> - arm_lpae_iopte *ptep) >>> + arm_lpae_iopte *ptep, int strict) >> >> DMA code should never ever be splitting blocks anyway, and frankly the TLB maintenance here is dodgy enough (since we can't reasonably do break-before make as VMSA says we should) that I *really* don't want to introduce any possibility of making it more asynchronous. I'd much rather just hard-code the expectation of strict == true for this. > > OK, I will hard-code strict=true for it. > > But since it never ever be happened, why did not give a warning at the beginning?
Because DMA code is not the only caller of iommu_map/unmap. It's perfectly legal in the IOMMU API to partially unmap a previous mapping such that a block entry needs to be split. The DMA API, however, is a lot more constrined, and thus by construction the iommu-dma layer will never generate a block-splitting iommu_unmap() except as a result of illegal DMA API usage, and we obviously do not need to optimise for that (you will get a warning about mismatched unmaps under dma-debug, but it's a bit too expensive to police in the general case).
Robin.
>>> { >>> struct io_pgtable_cfg *cfg = &data->iop.cfg; >>> arm_lpae_iopte pte, *tablep; >>> @@ -576,15 +576,18 @@ static size_t arm_lpae_split_blk_unmap(struct arm_lpae_io_pgtable *data, >>> } >>> if (unmap_idx < 0) >>> - return __arm_lpae_unmap(data, iova, size, lvl, tablep); >>> + return __arm_lpae_unmap(data, iova, size, lvl, tablep, strict); >>> io_pgtable_tlb_add_flush(&data->iop, iova, size, size, true); >>> + if (!strict) >>> + io_pgtable_tlb_sync(&data->iop); >>> + >>> return size; >>> } >>> static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, >>> unsigned long iova, size_t size, int lvl, >>> - arm_lpae_iopte *ptep) >>> + arm_lpae_iopte *ptep, int strict) >>> { >>> arm_lpae_iopte pte; >>> struct io_pgtable *iop = &data->iop; >>> @@ -609,7 +612,7 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, >>> io_pgtable_tlb_sync(iop); >>> ptep = iopte_deref(pte, data); >>> __arm_lpae_free_pgtable(data, lvl + 1, ptep); >>> - } else { >>> + } else if (strict) { >>> io_pgtable_tlb_add_flush(iop, iova, size, size, true); >>> } >>> @@ -620,25 +623,27 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, >>> * minus the part we want to unmap >>> */ >>> return arm_lpae_split_blk_unmap(data, iova, size, pte, >>> - lvl + 1, ptep); >>> + lvl + 1, ptep, strict); >>> } >>> /* Keep on walkin' */ >>> ptep = iopte_deref(pte, data); >>> - return __arm_lpae_unmap(data, iova, size, lvl + 1, ptep); >>> + return __arm_lpae_unmap(data, iova, size, lvl + 1, ptep, strict); >>> } >>> static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova, >>> size_t size) >>> { >>> + int strict = ((iova & IOMMU_STRICT_MODE_MASK) == IOMMU_STRICT); >>> struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops); >>> arm_lpae_iopte *ptep = data->pgd; >>> int lvl = ARM_LPAE_START_LVL(data); >>> + iova &= ~IOMMU_STRICT_MODE_MASK; >>> if (WARN_ON(iova >= (1ULL << data->iop.cfg.ias))) >>> return 0; >>> - return __arm_lpae_unmap(data, iova, size, lvl, ptep); >>> + return __arm_lpae_unmap(data, iova, size, lvl, ptep, strict); >>> } >>> static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops, >>> >> >> . >> >
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