diff options
| -rw-r--r-- | drivers/iommu/io-pgtable-arm.c | 72 |
1 files changed, 57 insertions, 15 deletions
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index 6334f51912ea..52700fa958c2 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -20,6 +20,7 @@ #define pr_fmt(fmt) "arm-lpae io-pgtable: " fmt +#include <linux/atomic.h> #include <linux/iommu.h> #include <linux/kernel.h> #include <linux/sizes.h> @@ -99,6 +100,8 @@ #define ARM_LPAE_PTE_ATTR_HI_MASK (((arm_lpae_iopte)6) << 52) #define ARM_LPAE_PTE_ATTR_MASK (ARM_LPAE_PTE_ATTR_LO_MASK | \ ARM_LPAE_PTE_ATTR_HI_MASK) +/* Software bit for solving coherency races */ +#define ARM_LPAE_PTE_SW_SYNC (((arm_lpae_iopte)1) << 55) /* Stage-1 PTE */ #define ARM_LPAE_PTE_AP_UNPRIV (((arm_lpae_iopte)1) << 6) @@ -249,15 +252,20 @@ static void __arm_lpae_free_pages(void *pages, size_t size, free_pages_exact(pages, size); } +static void __arm_lpae_sync_pte(arm_lpae_iopte *ptep, + struct io_pgtable_cfg *cfg) +{ + dma_sync_single_for_device(cfg->iommu_dev, __arm_lpae_dma_addr(ptep), + sizeof(*ptep), DMA_TO_DEVICE); +} + static void __arm_lpae_set_pte(arm_lpae_iopte *ptep, arm_lpae_iopte pte, struct io_pgtable_cfg *cfg) { *ptep = pte; if (!(cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA)) - dma_sync_single_for_device(cfg->iommu_dev, - __arm_lpae_dma_addr(ptep), - sizeof(pte), DMA_TO_DEVICE); + __arm_lpae_sync_pte(ptep, cfg); } static int __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, @@ -314,16 +322,30 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable *data, static arm_lpae_iopte arm_lpae_install_table(arm_lpae_iopte *table, arm_lpae_iopte *ptep, + arm_lpae_iopte curr, struct io_pgtable_cfg *cfg) { - arm_lpae_iopte new; + arm_lpae_iopte old, new; new = __pa(table) | ARM_LPAE_PTE_TYPE_TABLE; if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS) new |= ARM_LPAE_PTE_NSTABLE; - __arm_lpae_set_pte(ptep, new, cfg); - return new; + /* Ensure the table itself is visible before its PTE can be */ + wmb(); + + old = cmpxchg64_relaxed(ptep, curr, new); + + if ((cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA) || + (old & ARM_LPAE_PTE_SW_SYNC)) + return old; + + /* Even if it's not ours, there's no point waiting; just kick it */ + __arm_lpae_sync_pte(ptep, cfg); + if (old == curr) + WRITE_ONCE(*ptep, new | ARM_LPAE_PTE_SW_SYNC); + + return old; } static int __arm_lpae_map(struct arm_lpae_io_pgtable *data, unsigned long iova, @@ -332,6 +354,7 @@ static int __arm_lpae_map(struct arm_lpae_io_pgtable *data, unsigned long iova, { arm_lpae_iopte *cptep, pte; size_t block_size = ARM_LPAE_BLOCK_SIZE(lvl, data); + size_t tblsz = ARM_LPAE_GRANULE(data); struct io_pgtable_cfg *cfg = &data->iop.cfg; /* Find our entry at the current level */ @@ -346,17 +369,23 @@ static int __arm_lpae_map(struct arm_lpae_io_pgtable *data, unsigned long iova, return -EINVAL; /* Grab a pointer to the next level */ - pte = *ptep; + pte = READ_ONCE(*ptep); if (!pte) { - cptep = __arm_lpae_alloc_pages(ARM_LPAE_GRANULE(data), - GFP_ATOMIC, cfg); + cptep = __arm_lpae_alloc_pages(tblsz, GFP_ATOMIC, cfg); if (!cptep) return -ENOMEM; - arm_lpae_install_table(cptep, ptep, cfg); - } else if (!iopte_leaf(pte, lvl)) { + pte = arm_lpae_install_table(cptep, ptep, 0, cfg); + if (pte) + __arm_lpae_free_pages(cptep, tblsz, cfg); + } else if (!(cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA) && + !(pte & ARM_LPAE_PTE_SW_SYNC)) { + __arm_lpae_sync_pte(ptep, cfg); + } + + if (pte && !iopte_leaf(pte, lvl)) { cptep = iopte_deref(pte, data); - } else { + } else if (pte) { /* We require an unmap first */ WARN_ON(!selftest_running); return -EEXIST; @@ -502,7 +531,19 @@ static int arm_lpae_split_blk_unmap(struct arm_lpae_io_pgtable *data, __arm_lpae_init_pte(data, blk_paddr, pte, lvl, &tablep[i]); } - arm_lpae_install_table(tablep, ptep, cfg); + pte = arm_lpae_install_table(tablep, ptep, blk_pte, cfg); + if (pte != blk_pte) { + __arm_lpae_free_pages(tablep, tablesz, cfg); + /* + * We may race against someone unmapping another part of this + * block, but anything else is invalid. We can't misinterpret + * a page entry here since we're never at the last level. + */ + if (iopte_type(pte, lvl - 1) != ARM_LPAE_PTE_TYPE_TABLE) + return 0; + + tablep = iopte_deref(pte, data); + } if (unmap_idx < 0) return __arm_lpae_unmap(data, iova, size, lvl, tablep); @@ -523,7 +564,7 @@ static int __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, return 0; ptep += ARM_LPAE_LVL_IDX(iova, lvl, data); - pte = *ptep; + pte = READ_ONCE(*ptep); if (WARN_ON(!pte)) return 0; @@ -585,7 +626,8 @@ static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops, return 0; /* Grab the IOPTE we're interested in */ - pte = *(ptep + ARM_LPAE_LVL_IDX(iova, lvl, data)); + ptep += ARM_LPAE_LVL_IDX(iova, lvl, data); + pte = READ_ONCE(*ptep); /* Valid entry? */ if (!pte) |