On 28/04/2025 9:54 pm, Rob Clark wrote:
From: Rob Clark <robdcl...@chromium.org>In situations where mapping/unmapping squence can be controlled by userspace, attempting to map over a region that has not yet been unmapped is an error. But not something that should spam dmesg. Signed-off-by: Rob Clark <robdcl...@chromium.org> --- drivers/iommu/io-pgtable-arm.c | 18 ++++++++++++------ include/linux/io-pgtable.h | 8 ++++++++ 2 files changed, 20 insertions(+), 6 deletions(-) diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index f27965caf6a1..99523505dac5 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -475,7 +475,7 @@ static int __arm_lpae_map(struct arm_lpae_io_pgtable *data, unsigned long iova, cptep = iopte_deref(pte, data); } else if (pte) { /* We require an unmap first */ - WARN_ON(!selftest_running); + WARN_ON(!selftest_running && !(cfg->quirks & IO_PGTABLE_QUIRK_NO_WARN_ON));
If we are going to have this as a general mechanism then the selftests should use it as well.
Thanks, Robin.
return -EEXIST; }@@ -649,8 +649,10 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,unmap_idx_start = ARM_LPAE_LVL_IDX(iova, lvl, data); ptep += unmap_idx_start; pte = READ_ONCE(*ptep); - if (WARN_ON(!pte)) - return 0; + if (!pte) { + WARN_ON(!(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NO_WARN_ON)); + return -ENOENT; + }/* If the size matches this level, we're in the right place */if (size == ARM_LPAE_BLOCK_SIZE(lvl, data)) { @@ -660,8 +662,10 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, /* Find and handle non-leaf entries */ for (i = 0; i < num_entries; i++) { pte = READ_ONCE(ptep[i]); - if (WARN_ON(!pte)) + if (!pte) { + WARN_ON(!(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NO_WARN_ON)); break; + }if (!iopte_leaf(pte, lvl, iop->fmt)) {__arm_lpae_clear_pte(&ptep[i], &iop->cfg, 1); @@ -976,7 +980,8 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie) if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS | IO_PGTABLE_QUIRK_ARM_TTBR1 | IO_PGTABLE_QUIRK_ARM_OUTER_WBWA | - IO_PGTABLE_QUIRK_ARM_HD)) + IO_PGTABLE_QUIRK_ARM_HD | + IO_PGTABLE_QUIRK_NO_WARN_ON)) return NULL;data = arm_lpae_alloc_pgtable(cfg);@@ -1079,7 +1084,8 @@ arm_64_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie) struct arm_lpae_io_pgtable *data; typeof(&cfg->arm_lpae_s2_cfg.vtcr) vtcr = &cfg->arm_lpae_s2_cfg.vtcr;- if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_S2FWB))+ if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_S2FWB | + IO_PGTABLE_QUIRK_NO_WARN_ON)) return NULL;data = arm_lpae_alloc_pgtable(cfg);diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h index bba2a51c87d2..639b8f4fb87d 100644 --- a/include/linux/io-pgtable.h +++ b/include/linux/io-pgtable.h @@ -88,6 +88,13 @@ struct io_pgtable_cfg { * * IO_PGTABLE_QUIRK_ARM_HD: Enables dirty tracking in stage 1 pagetable. * IO_PGTABLE_QUIRK_ARM_S2FWB: Use the FWB format for the MemAttrs bits + * + * IO_PGTABLE_QUIRK_NO_WARN_ON: Do not WARN_ON() on conflicting + * mappings, but silently return -EEXISTS. Normally an attempt + * to map over an existing mapping would indicate some sort of + * kernel bug, which would justify the WARN_ON(). But for GPU + * drivers, this could be under control of userspace. Which + * deserves an error return, but not to spam dmesg. */ #define IO_PGTABLE_QUIRK_ARM_NS BIT(0) #define IO_PGTABLE_QUIRK_NO_PERMS BIT(1) @@ -97,6 +104,7 @@ struct io_pgtable_cfg { #define IO_PGTABLE_QUIRK_ARM_OUTER_WBWA BIT(6) #define IO_PGTABLE_QUIRK_ARM_HD BIT(7) #define IO_PGTABLE_QUIRK_ARM_S2FWB BIT(8) + #define IO_PGTABLE_QUIRK_NO_WARN_ON BIT(9) unsigned long quirks; unsigned long pgsize_bitmap; unsigned int ias;
