linux-kernel - Re: [PATCH] drm/amdkfd: dqm fence memory corruption

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Date:   Wed, 27 Jan 2021 16:50:07 -0500
From:   Felix Kuehling <felix.kuehling@....com>
To:     Qu Huang <jinsdb@....com>
Cc:     alexander.deucher@....com, christian.koenig@....com,
        airlied@...ux.ie, daniel@...ll.ch, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/amdkfd: dqm fence memory corruption

Am 2021-01-27 um 7:33 a.m. schrieb Qu Huang:
> Amdgpu driver uses 4-byte data type as DQM fence memory,
> and transmits GPU address of fence memory to microcode
> through query status PM4 message. However, query status
> PM4 message definition and microcode processing are all
> processed according to 8 bytes. Fence memory only allocates
> 4 bytes of memory, but microcode does write 8 bytes of memory,
> so there is a memory corruption.

Thank you for pointing out that discrepancy. That's a good catch!

I'd prefer to fix this properly by making dqm->fence_addr a u64 pointer.
We should probably also fix up the query_status and
amdkfd_fence_wait_timeout function interfaces to use a 64 bit fence
values everywhere to be consistent.

Regards,
  Felix


>
> Signed-off-by: Qu Huang <jinsdb@....com>
> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> index e686ce2..8b38d0c 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> @@ -1161,7 +1161,7 @@ static int start_cpsch(struct device_queue_manager *dqm)
>  	pr_debug("Allocating fence memory\n");
>  
>  	/* allocate fence memory on the gart */
> -	retval = kfd_gtt_sa_allocate(dqm->dev, sizeof(*dqm->fence_addr),
> +	retval = kfd_gtt_sa_allocate(dqm->dev, sizeof(uint64_t),
>  					&dqm->fence_mem);
>  
>  	if (retval)