[PATCH] drm/vgem: Restore mmap functionality

[Thomas Zimmermann]

Hi

Am 09.07.21 um 16:43 schrieb Daniel Vetter:
> On Fri, Jul 9, 2021 at 1:47 PM Thomas Zimmermann <tzimmermann at suse.de> wrote:
>>
>> Commit 375cca1cfeb5 ("drm/vgem: Implement mmap as GEM object function")
>> accidentally removed the actual mmap functionality from vgem. Restore
>> the original implementation and VMA flags.
> 
> Ah yes that explains things.
> 
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Apparently, this fix fails a number of other tests. [1] Can we revert 
the original patch for now? I'd like to have time to investigate.

Best regards
Thomas


[1] 
https://lore.kernel.org/intel-gfx/20210709154256.12005-1-tzimmermann@suse.de/T/#maa12be2a6d4b6a4ed8cb05e98f00b8955638c518

>>
>> Fixes access to unmapped memory:
>>
>> [  106.591744] BUG: KASAN: vmalloc-out-of-bounds in do_fault+0x38/0x480
>> [  106.598154] Read of size 8 at addr ffffffffc10c44a8 by task vgem_basic/1514
>> [  106.605173]
>> [  106.606678] CPU: 1 PID: 1514 Comm: vgem_basic Tainted: G            E     5.13.0-1-default+ #990
>> [  106.615535] Hardware name: Dell Inc. OptiPlex 9020/0N4YC8, BIOS A24 10/24/2018
>> [  106.622818] Call Trace:
>> [  106.625289]  dump_stack+0xa5/0xdc
>> [  106.628642]  print_address_description.constprop.0+0x18/0x100
>> [  106.634439]  ? do_fault+0x38/0x480
>> [  106.637872]  kasan_report.cold+0x7c/0xd8
>> [  106.641834]  ? do_fault+0x38/0x480
>> [  106.645274]  do_fault+0x38/0x480
>> [  106.648535]  __handle_mm_fault+0x935/0xb00
>> [  106.652676]  ? vm_iomap_memory+0xe0/0xe0
>> [  106.656634]  ? __lock_release+0x12f/0x4e0
>> [  106.660696]  ? count_memcg_event_mm.part.0+0xb9/0x190
>> [  106.665799]  handle_mm_fault+0xd0/0x370
>> [  106.669675]  do_user_addr_fault+0x2a0/0x8c0
>> [  106.673908]  exc_page_fault+0x64/0xf0
>> [  106.677604]  ? asm_exc_page_fault+0x8/0x30
>> [  106.681739]  asm_exc_page_fault+0x1e/0x30
>> [  106.685782] RIP: 0033:0x402e12
>> ...
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
>> Fixes: 375cca1cfeb5 ("drm/vgem: Implement mmap as GEM object function")
>> Cc: Thomas Zimmermann <tzimmermann at suse.de>
>> Cc: Christian König <christian.koenig at amd.com>
>> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
>> Cc: "Christian König" <christian.koenig at amd.com>
>> Cc: Melissa Wen <melissa.srw at gmail.com>
>> Cc: Jason Gunthorpe <jgg at ziepe.ca>
>> Cc: Gerd Hoffmann <kraxel at redhat.com>
>> Cc: Lee Jones <lee.jones at linaro.org>
>> ---
>>   drivers/gpu/drm/vgem/vgem_drv.c | 11 ++++++++++-
>>   1 file changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
>> index df634aa52638..f50fd10c4fad 100644
>> --- a/drivers/gpu/drm/vgem/vgem_drv.c
>> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
>> @@ -364,8 +364,17 @@ static void vgem_prime_vunmap(struct drm_gem_object *obj, struct dma_buf_map *ma
>>
>>   static int vgem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
>>   {
>> +       int ret;
>> +
>> +       if (!obj->filp)
>> +               return -ENODEV;
>> +
>> +       ret = call_mmap(obj->filp, vma);
>> +       if (ret)
>> +               return ret;
>> +
>>          vma_set_file(vma, obj->filp);
>> -       vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
>> +       vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
>>          vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
>>          vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
>>
>> --
>> 2.32.0
>>
> 
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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