Defer pages allocation until their first access. v2: - Don't deal with FAULT_FLAG_INTERRUPTIBLE - Make sure bo->backing.pages is never an ERR_PTR() - Drop a useless vm_fault_t local var - Fix comment in panthor_gem_fault()
Signed-off-by: Boris Brezillon <[email protected]> --- drivers/gpu/drm/panthor/panthor_gem.c | 127 ++++++++++++++++---------- 1 file changed, 77 insertions(+), 50 deletions(-) diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c index 1a301e5174ec..7e966fbe500f 100644 --- a/drivers/gpu/drm/panthor/panthor_gem.c +++ b/drivers/gpu/drm/panthor/panthor_gem.c @@ -129,18 +129,20 @@ panthor_gem_backing_cleanup_locked(struct panthor_gem_object *bo) static int panthor_gem_backing_get_pages_locked(struct panthor_gem_object *bo) { + struct page **pages; + dma_resv_assert_held(bo->base.resv); if (bo->backing.pages) return 0; - bo->backing.pages = drm_gem_get_pages(&bo->base); - if (IS_ERR(bo->backing.pages)) { - drm_dbg_kms(bo->base.dev, "Failed to get pages (%pe)\n", - bo->backing.pages); - return PTR_ERR(bo->backing.pages); + pages = drm_gem_get_pages(&bo->base); + if (IS_ERR(pages)) { + drm_dbg_kms(bo->base.dev, "Failed to get pages (%pe)\n", pages); + return PTR_ERR(pages); } + bo->backing.pages = pages; return 0; } @@ -601,15 +603,6 @@ static int panthor_gem_mmap(struct drm_gem_object *obj, struct vm_area_struct *v if (is_cow_mapping(vma->vm_flags)) return -EINVAL; - dma_resv_lock(obj->resv, NULL); - ret = panthor_gem_backing_get_pages_locked(bo); - if (!ret) - ret = panthor_gem_prep_for_cpu_map_locked(bo); - dma_resv_unlock(obj->resv); - - if (ret) - return ret; - vm_flags_set(vma, VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); if (should_map_wc(bo)) @@ -629,82 +622,116 @@ static enum drm_gem_object_status panthor_gem_status(struct drm_gem_object *obj) return res; } -static bool try_map_pmd(struct vm_fault *vmf, unsigned long addr, struct page *page) +static vm_fault_t insert_page(struct vm_fault *vmf, struct page *page) { + struct vm_area_struct *vma = vmf->vma; + #ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP unsigned long pfn = page_to_pfn(page); unsigned long paddr = pfn << PAGE_SHIFT; - bool aligned = (addr & ~PMD_MASK) == (paddr & ~PMD_MASK); + bool aligned = (vmf->address & ~PMD_MASK) == (paddr & ~PMD_MASK); if (aligned && pmd_none(*vmf->pmd) && folio_test_pmd_mappable(page_folio(page))) { pfn &= PMD_MASK >> PAGE_SHIFT; if (vmf_insert_pfn_pmd(vmf, pfn, false) == VM_FAULT_NOPAGE) - return true; + return VM_FAULT_NOPAGE; } #endif - return false; + return vmf_insert_pfn(vma, vmf->address, page_to_pfn(page)); } -static vm_fault_t panthor_gem_fault(struct vm_fault *vmf) +static vm_fault_t nonblocking_page_setup(struct vm_fault *vmf, pgoff_t page_offset) { struct vm_area_struct *vma = vmf->vma; - struct drm_gem_object *obj = vma->vm_private_data; struct panthor_gem_object *bo = to_panthor_bo(vma->vm_private_data); - loff_t num_pages = obj->size >> PAGE_SHIFT; vm_fault_t ret; - pgoff_t page_offset; - unsigned long pfn; - /* Offset to faulty address in the VMA. */ - page_offset = vmf->pgoff - vma->vm_pgoff; + if (!dma_resv_trylock(bo->base.resv)) + return VM_FAULT_RETRY; - dma_resv_lock(bo->base.resv, NULL); + if (bo->backing.pages) + ret = insert_page(vmf, bo->backing.pages[page_offset]); + else + ret = VM_FAULT_RETRY; - if (page_offset >= num_pages || - drm_WARN_ON_ONCE(obj->dev, !bo->backing.pages)) { - ret = VM_FAULT_SIGBUS; - goto out; + dma_resv_unlock(bo->base.resv); + return ret; +} + +static vm_fault_t blocking_page_setup(struct vm_fault *vmf, + struct panthor_gem_object *bo, + pgoff_t page_offset, bool mmap_lock_held) +{ + vm_fault_t ret; + int err; + + err = dma_resv_lock_interruptible(bo->base.resv, NULL); + if (err) + return mmap_lock_held ? VM_FAULT_NOPAGE : VM_FAULT_RETRY; + + err = panthor_gem_backing_get_pages_locked(bo); + if (!err) + err = panthor_gem_prep_for_cpu_map_locked(bo); + + if (err) { + ret = mmap_lock_held ? VM_FAULT_SIGBUS : VM_FAULT_RETRY; + } else { + struct page *page = bo->backing.pages[page_offset]; + + if (mmap_lock_held) + ret = insert_page(vmf, page); + else + ret = VM_FAULT_RETRY; } - if (try_map_pmd(vmf, vmf->address, bo->backing.pages[page_offset])) { - ret = VM_FAULT_NOPAGE; - goto out; - } - - pfn = page_to_pfn(bo->backing.pages[page_offset]); - ret = vmf_insert_pfn(vma, vmf->address, pfn); - - out: dma_resv_unlock(bo->base.resv); return ret; } -static void panthor_gem_vm_open(struct vm_area_struct *vma) +static vm_fault_t panthor_gem_fault(struct vm_fault *vmf) { + struct vm_area_struct *vma = vmf->vma; struct panthor_gem_object *bo = to_panthor_bo(vma->vm_private_data); + loff_t num_pages = bo->base.size >> PAGE_SHIFT; + pgoff_t page_offset; + vm_fault_t ret; - drm_WARN_ON(bo->base.dev, drm_gem_is_imported(&bo->base)); + /* Offset to faulty address in the VMA. */ + page_offset = vmf->pgoff - vma->vm_pgoff; + if (page_offset >= num_pages) + return VM_FAULT_SIGBUS; - dma_resv_lock(bo->base.resv, NULL); + ret = nonblocking_page_setup(vmf, page_offset); + if (ret != VM_FAULT_RETRY) + return ret; - /* We should have already pinned the pages when the buffer was first - * mmap'd, vm_open() just grabs an additional reference for the new - * mm the vma is getting copied into (ie. on fork()). - */ - drm_WARN_ON_ONCE(bo->base.dev, !bo->backing.pages); + /* Check if we're allowed to retry. */ + if (fault_flag_allow_retry_first(vmf->flags)) { + /* If we're allowed to retry but not wait here, return + * immediately, the wait will be done when the fault + * handler is called again, with the mmap_lock held. + */ + if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT) + return VM_FAULT_RETRY; - dma_resv_unlock(bo->base.resv); + /* Wait with the mmap lock released, if we're allowed to. */ + drm_gem_object_get(&bo->base); + mmap_read_unlock(vmf->vma->vm_mm); + ret = blocking_page_setup(vmf, bo, page_offset, false); + drm_gem_object_put(&bo->base); + return ret; + } - drm_gem_vm_open(vma); + return blocking_page_setup(vmf, bo, page_offset, true); } const struct vm_operations_struct panthor_gem_vm_ops = { .fault = panthor_gem_fault, - .open = panthor_gem_vm_open, + .open = drm_gem_vm_open, .close = drm_gem_vm_close, }; -- 2.52.0
