[PATCH v3 1/1] drm/ttm: Fix COW check

[Christian König]

Am 13.07.21 um 17:28 schrieb Alex Deucher:
> On Tue, Jul 13, 2021 at 2:57 AM Christian König
> <ckoenig.leichtzumerken at gmail.com> wrote:
>>
>>
>> Am 13.07.21 um 00:06 schrieb Felix Kuehling:
>>> KFD Thunk maps invisible VRAM BOs with PROT_NONE, MAP_PRIVATE.
>>> is_cow_mapping returns true for these mappings. Add a check for
>>> vm_flags & VM_WRITE to avoid mmap failures on private read-only or
>>> PROT_NONE mappings.
>>>
>>> v2: protect against mprotect making a mapping writable after the fact
>>> v3: update driver-specific vm_operations_structs
>>>
>>> Fixes: f91142c62161 ("drm/ttm: nuke VM_MIXEDMAP on BO mappings v3")
>>> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
>>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>> Reviewed-by: Christian König <christian.koenig at amd.com>
> Are you planning to push this to drm-misc?

Yes, just didn't found time yesterday.

Christian.

>
> Alex
>
>>> ---
>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c  |  3 ++-
>>>    drivers/gpu/drm/nouveau/nouveau_gem.c    |  3 ++-
>>>    drivers/gpu/drm/radeon/radeon_gem.c      |  3 ++-
>>>    drivers/gpu/drm/ttm/ttm_bo_vm.c          | 14 +++++++++++++-
>>>    drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c |  1 +
>>>    include/drm/ttm/ttm_bo_api.h             |  4 ++++
>>>    6 files changed, 24 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>> index b3404c43a911..1aa750a6a5d2 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>> @@ -79,7 +79,8 @@ static const struct vm_operations_struct amdgpu_gem_vm_ops = {
>>>        .fault = amdgpu_gem_fault,
>>>        .open = ttm_bo_vm_open,
>>>        .close = ttm_bo_vm_close,
>>> -     .access = ttm_bo_vm_access
>>> +     .access = ttm_bo_vm_access,
>>> +     .mprotect = ttm_bo_vm_mprotect
>>>    };
>>>
>>>    static void amdgpu_gem_object_free(struct drm_gem_object *gobj)
>>> diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
>>> index 5b27845075a1..164ea564bb7a 100644
>>> --- a/drivers/gpu/drm/nouveau/nouveau_gem.c
>>> +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
>>> @@ -70,7 +70,8 @@ static const struct vm_operations_struct nouveau_ttm_vm_ops = {
>>>        .fault = nouveau_ttm_fault,
>>>        .open = ttm_bo_vm_open,
>>>        .close = ttm_bo_vm_close,
>>> -     .access = ttm_bo_vm_access
>>> +     .access = ttm_bo_vm_access,
>>> +     .mprotect = ttm_bo_vm_mprotect
>>>    };
>>>
>>>    void
>>> diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
>>> index 458f92a70887..c19ad07eb7b5 100644
>>> --- a/drivers/gpu/drm/radeon/radeon_gem.c
>>> +++ b/drivers/gpu/drm/radeon/radeon_gem.c
>>> @@ -77,7 +77,8 @@ static const struct vm_operations_struct radeon_gem_vm_ops = {
>>>        .fault = radeon_gem_fault,
>>>        .open = ttm_bo_vm_open,
>>>        .close = ttm_bo_vm_close,
>>> -     .access = ttm_bo_vm_access
>>> +     .access = ttm_bo_vm_access,
>>> +     .mprotect = ttm_bo_vm_mprotect
>>>    };
>>>
>>>    static void radeon_gem_object_free(struct drm_gem_object *gobj)
>>> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
>>> index f56be5bc0861..fb325bad5db6 100644
>>> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
>>> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
>>> @@ -542,17 +542,29 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
>>>    }
>>>    EXPORT_SYMBOL(ttm_bo_vm_access);
>>>
>>> +int ttm_bo_vm_mprotect(struct vm_area_struct *vma, unsigned long start,
>>> +                    unsigned long end, unsigned long newflags)
>>> +{
>>> +     /* Enforce no COW since would have really strange behavior with it. */
>>> +     if (is_cow_mapping(newflags) && (newflags & VM_WRITE))
>>> +             return -EINVAL;
>>> +
>>> +     return 0;
>>> +}
>>> +EXPORT_SYMBOL(ttm_bo_vm_mprotect);
>>> +
>>>    static const struct vm_operations_struct ttm_bo_vm_ops = {
>>>        .fault = ttm_bo_vm_fault,
>>>        .open = ttm_bo_vm_open,
>>>        .close = ttm_bo_vm_close,
>>>        .access = ttm_bo_vm_access,
>>> +     .mprotect = ttm_bo_vm_mprotect,
>>>    };
>>>
>>>    int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
>>>    {
>>>        /* Enforce no COW since would have really strange behavior with it. */
>>> -     if (is_cow_mapping(vma->vm_flags))
>>> +     if (is_cow_mapping(vma->vm_flags) && (vma->vm_flags & VM_WRITE))
>>>                return -EINVAL;
>>>
>>>        ttm_bo_get(bo);
>>> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
>>> index e6b1f98ec99f..e4bf7dc99320 100644
>>> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
>>> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
>>> @@ -61,6 +61,7 @@ int vmw_mmap(struct file *filp, struct vm_area_struct *vma)
>>>                .fault = vmw_bo_vm_fault,
>>>                .open = ttm_bo_vm_open,
>>>                .close = ttm_bo_vm_close,
>>> +             .mprotect = ttm_bo_vm_mprotect,
>>>    #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>>>                .huge_fault = vmw_bo_vm_huge_fault,
>>>    #endif
>>> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
>>> index f681bbdbc698..40eb95875355 100644
>>> --- a/include/drm/ttm/ttm_bo_api.h
>>> +++ b/include/drm/ttm/ttm_bo_api.h
>>> @@ -605,6 +605,10 @@ void ttm_bo_vm_close(struct vm_area_struct *vma);
>>>
>>>    int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
>>>                     void *buf, int len, int write);
>>> +
>>> +int ttm_bo_vm_mprotect(struct vm_area_struct *vma, unsigned long start,
>>> +                    unsigned long end, unsigned long newflags);
>>> +
>>>    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);