From 267d51d77fdae8708b94e1a24b8e5d961297edb7 Mon Sep 17 00:00:00 2001 From: Andrey Grodzovsky Date: Wed, 12 May 2021 10:26:33 -0400 Subject: [PATCH] drm/ttm: Remap all page faults to per process dummy page. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit On device removal reroute all CPU mappings to dummy page. v3: Remove loop to find DRM file and instead access it by vma->vm_file->private_data. Move dummy page installation into a separate function. v4: Map the entire BOs VA space into on demand allocated dummy page on the first fault for that BO. v5: Remove duplicate return. v6: Polish ttm_bo_vm_dummy_page, remove superfluous code. Signed-off-by: Andrey Grodzovsky Reviewed-by: Christian König Link: https://patchwork.freedesktop.org/patch/msgid/20210512142648.666476-2-andrey.grodzovsky@amd.com --- drivers/gpu/drm/ttm/ttm_bo_vm.c | 54 ++++++++++++++++++++++++++++++++++++++++- include/drm/ttm/ttm_bo_api.h | 2 ++ 2 files changed, 55 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index b31b18058965..7ff9fd551357 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -34,6 +34,8 @@ #include #include #include +#include +#include #include #include #include @@ -380,19 +382,69 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf, } EXPORT_SYMBOL(ttm_bo_vm_fault_reserved); +static void ttm_bo_release_dummy_page(struct drm_device *dev, void *res) +{ + struct page *dummy_page = (struct page *)res; + + __free_page(dummy_page); +} + +vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot) +{ + struct vm_area_struct *vma = vmf->vma; + struct ttm_buffer_object *bo = vma->vm_private_data; + struct drm_device *ddev = bo->base.dev; + vm_fault_t ret = VM_FAULT_NOPAGE; + unsigned long address; + unsigned long pfn; + struct page *page; + + /* Allocate new dummy page to map all the VA range in this VMA to it*/ + page = alloc_page(GFP_KERNEL | __GFP_ZERO); + if (!page) + return VM_FAULT_OOM; + + /* Set the page to be freed using drmm release action */ + if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page, page)) + return VM_FAULT_OOM; + + pfn = page_to_pfn(page); + + /* Prefault the entire VMA range right away to avoid further faults */ + for (address = vma->vm_start; address < vma->vm_end; address += PAGE_SIZE) { + + if (vma->vm_flags & VM_MIXEDMAP) + ret = vmf_insert_mixed_prot(vma, address, + __pfn_to_pfn_t(pfn, PFN_DEV), + prot); + else + ret = vmf_insert_pfn_prot(vma, address, pfn, prot); + } + + return ret; +} +EXPORT_SYMBOL(ttm_bo_vm_dummy_page); + vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf) { struct vm_area_struct *vma = vmf->vma; pgprot_t prot; struct ttm_buffer_object *bo = vma->vm_private_data; + struct drm_device *ddev = bo->base.dev; vm_fault_t ret; + int idx; ret = ttm_bo_vm_reserve(bo, vmf); if (ret) return ret; prot = vma->vm_page_prot; - ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1); + if (drm_dev_enter(ddev, &idx)) { + ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1); + drm_dev_exit(idx); + } else { + ret = ttm_bo_vm_dummy_page(vmf, prot); + } if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) return ret; diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h index 639521880c29..254ede97f8e3 100644 --- a/include/drm/ttm/ttm_bo_api.h +++ b/include/drm/ttm/ttm_bo_api.h @@ -620,4 +620,6 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr, void *buf, int len, int write); bool ttm_bo_delayed_delete(struct ttm_device *bdev, bool remove_all); +vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot); + #endif -- 2.11.0