On 7/31/26 18:43, Paolo Bonzini wrote: > This ensures that fixup_user_fault() users see a writable PTE when > they request one. The flip side is that vmw_bo_vm_fault() now has > to record by hand the write fault, because .pfn_mkwrite() is > not invoked. > > Prefaulting works as before because only the first entry comes > out writable, while the following ones still end up executing > the .pfn_mkwrite() callback.
Please split that patch for TTM/VMWGFX. The TTM part looks reasonable, but VMGFX is a completely different beast. Regards, Christian. > > Signed-off-by: Paolo Bonzini <[email protected]> > --- > drivers/gpu/drm/ttm/ttm_bo_vm.c | 3 +- > drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c | 42 ++++++++++++---------- > 2 files changed, 26 insertions(+), 19 deletions(-) > > diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c > index a80510489c45..ef27a2d7afc0 100644 > --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c > +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c > @@ -263,7 +263,8 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf, > * at arbitrary times while the data is mmap'ed. > * See vmf_insert_pfn_prot() for a discussion. > */ > - ret = vmf_insert_pfn_prot(vma, address, pfn, prot); > + ret = __vmf_insert_pfn_prot(vma, address, pfn, prot, > + i == 0 && !!(vmf->flags & > FAULT_FLAG_WRITE)); > > /* Never error on prefaulted PTEs */ > if (unlikely((ret & VM_FAULT_ERROR))) { > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c > b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c > index 45561bc1c9ef..2cc490e7d758 100644 > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c > @@ -398,15 +398,33 @@ void vmw_bo_dirty_clear_res(struct vmw_resource *res) > dirty->end = res_start; > } > > +static vm_fault_t vmw_bo_dirty_mkwrite(struct vm_fault *vmf, struct > ttm_buffer_object *bo) > +{ > + unsigned long page_offset; > + struct vmw_bo *vbo = to_vmw_bo(&bo->base); > + > + page_offset = vmf->pgoff - drm_vma_node_start(&bo->base.vma_node); > + if (unlikely(page_offset >= PFN_UP(bo->resource->size))) > + return VM_FAULT_SIGBUS; > + > + if (vbo->dirty && vbo->dirty->method == VMW_BO_DIRTY_MKWRITE && > + !test_bit(page_offset, &vbo->dirty->bitmap[0])) { > + struct vmw_bo_dirty *dirty = vbo->dirty; > + > + __set_bit(page_offset, &dirty->bitmap[0]); > + dirty->start = min(dirty->start, page_offset); > + dirty->end = max(dirty->end, page_offset + 1); > + } > + return 0; > +} > + > vm_fault_t vmw_bo_vm_mkwrite(struct vm_fault *vmf) > { > struct vm_area_struct *vma = vmf->vma; > struct ttm_buffer_object *bo = (struct ttm_buffer_object *) > vma->vm_private_data; > vm_fault_t ret; > - unsigned long page_offset; > unsigned int save_flags; > - struct vmw_bo *vbo = to_vmw_bo(&bo->base); > > /* > * mkwrite() doesn't handle the VM_FAULT_RETRY return value correctly. > @@ -419,22 +437,7 @@ vm_fault_t vmw_bo_vm_mkwrite(struct vm_fault *vmf) > if (ret) > return ret; > > - page_offset = vmf->pgoff - drm_vma_node_start(&bo->base.vma_node); > - if (unlikely(page_offset >= PFN_UP(bo->resource->size))) { > - ret = VM_FAULT_SIGBUS; > - goto out_unlock; > - } > - > - if (vbo->dirty && vbo->dirty->method == VMW_BO_DIRTY_MKWRITE && > - !test_bit(page_offset, &vbo->dirty->bitmap[0])) { > - struct vmw_bo_dirty *dirty = vbo->dirty; > - > - __set_bit(page_offset, &dirty->bitmap[0]); > - dirty->start = min(dirty->start, page_offset); > - dirty->end = max(dirty->end, page_offset + 1); > - } > - > -out_unlock: > + ret = vmw_bo_dirty_mkwrite(vmf, bo); > dma_resv_unlock(bo->base.resv); > return ret; > } > @@ -484,6 +487,9 @@ vm_fault_t vmw_bo_vm_fault(struct vm_fault *vmf) > prot = vm_get_page_prot(vma->vm_flags); > > ret = ttm_bo_vm_fault_reserved(vmf, prot, num_prefault); > + if (ret == VM_FAULT_NOPAGE && (vmf->flags & FAULT_FLAG_WRITE)) > + WARN_ON_ONCE(vmw_bo_dirty_mkwrite(vmf, bo)); > + > if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) > return ret; >
