From 25dda4dabeeb12af5209b0183c788ef2a88dabbe Mon Sep 17 00:00:00 2001 From: Jon Bloomfield Date: Thu, 12 Jul 2018 19:53:10 +0100 Subject: [PATCH] drm/i915/gtt: Add read only pages to gen8_pte_encode We can set a bit inside the ppGTT PTE to indicate a page is read-only; writes from the GPU will be discarded. We can use this to protect pages and in particular support read-only userptr mappings (necessary for importing PROT_READ vma). Signed-off-by: Jon Bloomfield Signed-off-by: Chris Wilson Cc: Joonas Lahtinen Cc: Matthew Auld Reviewed-by: Joonas Lahtinen Reviewed-by: Matthew Auld Link: https://patchwork.freedesktop.org/patch/msgid/20180712185315.3288-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem_gtt.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c index 502353b9bf84..b74f1ed03bae 100644 --- a/drivers/gpu/drm/i915/i915_gem_gtt.c +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c @@ -244,10 +244,13 @@ static void clear_pages(struct i915_vma *vma) } static gen8_pte_t gen8_pte_encode(dma_addr_t addr, - enum i915_cache_level level) + enum i915_cache_level level, + u32 flags) { - gen8_pte_t pte = _PAGE_PRESENT | _PAGE_RW; - pte |= addr; + gen8_pte_t pte = addr | _PAGE_PRESENT | _PAGE_RW; + + if (unlikely(flags & PTE_READ_ONLY)) + pte &= ~_PAGE_RW; switch (level) { case I915_CACHE_NONE: @@ -721,7 +724,7 @@ static void gen8_initialize_pt(struct i915_address_space *vm, struct i915_page_table *pt) { fill_px(vm, pt, - gen8_pte_encode(vm->scratch_page.daddr, I915_CACHE_LLC)); + gen8_pte_encode(vm->scratch_page.daddr, I915_CACHE_LLC, 0)); } static void gen6_initialize_pt(struct gen6_hw_ppgtt *ppgtt, @@ -869,7 +872,7 @@ static bool gen8_ppgtt_clear_pt(struct i915_address_space *vm, unsigned int pte = gen8_pte_index(start); unsigned int pte_end = pte + num_entries; const gen8_pte_t scratch_pte = - gen8_pte_encode(vm->scratch_page.daddr, I915_CACHE_LLC); + gen8_pte_encode(vm->scratch_page.daddr, I915_CACHE_LLC, 0); gen8_pte_t *vaddr; GEM_BUG_ON(num_entries > pt->used_ptes); @@ -1044,7 +1047,7 @@ gen8_ppgtt_insert_pte_entries(struct i915_hw_ppgtt *ppgtt, enum i915_cache_level cache_level) { struct i915_page_directory *pd; - const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level); + const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, 0); gen8_pte_t *vaddr; bool ret; @@ -1112,7 +1115,7 @@ static void gen8_ppgtt_insert_huge_entries(struct i915_vma *vma, struct sgt_dma *iter, enum i915_cache_level cache_level) { - const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level); + const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, 0); u64 start = vma->node.start; dma_addr_t rem = iter->sg->length; @@ -1578,7 +1581,7 @@ static void gen8_dump_ppgtt(struct i915_hw_ppgtt *ppgtt, struct seq_file *m) { struct i915_address_space *vm = &ppgtt->vm; const gen8_pte_t scratch_pte = - gen8_pte_encode(vm->scratch_page.daddr, I915_CACHE_LLC); + gen8_pte_encode(vm->scratch_page.daddr, I915_CACHE_LLC, 0); u64 start = 0, length = ppgtt->vm.total; if (use_4lvl(vm)) { @@ -2461,7 +2464,7 @@ static void gen8_ggtt_insert_page(struct i915_address_space *vm, gen8_pte_t __iomem *pte = (gen8_pte_t __iomem *)ggtt->gsm + (offset >> PAGE_SHIFT); - gen8_set_pte(pte, gen8_pte_encode(addr, level)); + gen8_set_pte(pte, gen8_pte_encode(addr, level, 0)); ggtt->invalidate(vm->i915); } @@ -2474,7 +2477,7 @@ static void gen8_ggtt_insert_entries(struct i915_address_space *vm, struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm); struct sgt_iter sgt_iter; gen8_pte_t __iomem *gtt_entries; - const gen8_pte_t pte_encode = gen8_pte_encode(0, level); + const gen8_pte_t pte_encode = gen8_pte_encode(0, level, 0); dma_addr_t addr; gtt_entries = (gen8_pte_t __iomem *)ggtt->gsm; @@ -2542,7 +2545,7 @@ static void gen8_ggtt_clear_range(struct i915_address_space *vm, unsigned first_entry = start >> PAGE_SHIFT; unsigned num_entries = length >> PAGE_SHIFT; const gen8_pte_t scratch_pte = - gen8_pte_encode(vm->scratch_page.daddr, I915_CACHE_LLC); + gen8_pte_encode(vm->scratch_page.daddr, I915_CACHE_LLC, 0); gen8_pte_t __iomem *gtt_base = (gen8_pte_t __iomem *)ggtt->gsm + first_entry; const int max_entries = ggtt_total_entries(ggtt) - first_entry; -- GitLab