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

Christian König ckoenig.leichtzumerken at gmail.com
Fri Jul 23 08:33:48 UTC 2021



Am 23.07.21 um 10:21 schrieb Daniel Vetter:
> On Wed, Jul 14, 2021 at 10:51 AM Christian König
> <christian.koenig at amd.com> wrote:
>>
>>
>> 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.
> This is pushed to the wrong tree drm-misc-next-fixes, should have been
> in drm-misc-fixes. Please be careful with that because every time that
> goes wrong the script gets confused about which the current tree is,
> and pushes the wrong tree to linux-next branches.
>
> I'm going to hard-reset drm-misc-next-fixes now and hope that's good
> enough to fix things up (since Thomas is not around all the time for
> this merge window).

STOP! I'm about to push a revert for this patch.

And yes that was pushed to the wrong branch, but it turned out that this 
was fortunate since the patch doesn't work correctly.

Christian.

> -Daniel
>
>
>> 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);
>



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