[PATCH] drm/xe: Unmap userptr in MMU invalidation notifier

[Zeng, Oak]

Hi Matt

> -----Original Message-----
> From: Intel-xe <intel-xe-bounces at lists.freedesktop.org> On Behalf Of
> Matthew Brost
> Sent: Friday, April 26, 2024 7:33 PM
> To: intel-xe at lists.freedesktop.org
> Cc: Brost, Matthew <matthew.brost at intel.com>; Thomas Hellström
> <thomas.hellstrom at linux.intel.com>; stable at vger.kernel.org
> Subject: [PATCH] drm/xe: Unmap userptr in MMU invalidation notifier
> 
> To be secure, when a userptr is invalidated the pages should be dma
> unmapped ensuring the device can no longer touch the invalidated pages.
> 
> Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
> Fixes: 12f4b58a37f4 ("drm/xe: Use hmm_range_fault to populate user
> pages")
> Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> Cc: stable at vger.kernel.org # 6.8
> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_vm.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index dfd31b346021..964a5b4d47d8 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -637,6 +637,9 @@ static bool vma_userptr_invalidate(struct
> mmu_interval_notifier *mni,
>  		XE_WARN_ON(err);
>  	}
> 
> +	if (userptr->sg)
> +		xe_hmm_userptr_free_sg(uvma);

Just some thoughts here. I think when we introduce system allocator, above should be made conditional. We should dma unmap userptr only for normal userptr but not for userptr created for system allocator (fault usrptr in the system allocator series). Because for system allocator the dma-unmapping would be part of the garbage collector and vma destroy process. Right?

Oak 

> +
>  	trace_xe_vma_userptr_invalidate_complete(vma);
> 
>  	return true;
> --
> 2.34.1