[PATCH 1/2] drm/msm: Drop update_fences()

[PATCH 1/2] drm/msm: Drop update_fences()

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

I noticed while looking at some traces, that we could miss calls to
msm_update_fence(), as the irq could have raced with retire_submits()
which could have already popped the last submit on a ring out of the
queue of in-flight submits.  But walking the list of submits in the
irq handler isn't really needed, as dma_fence_is_signaled() will dtrt.
So lets just drop it entirely.

Reported-by: Steev Klimaszewski <steev@kali.org>
Fixes: 95d1deb02a9c ("drm/msm/gem: Add fenced vma unpin")
Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/msm_gpu.c | 22 ++--------------------
 1 file changed, 2 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index e59a757578df..b61078f0cd0f 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -176,24 +176,6 @@ int msm_gpu_hw_init(struct msm_gpu *gpu)
 	return ret;
 }
 
-static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
-		uint32_t fence)
-{
-	struct msm_gem_submit *submit;
-	unsigned long flags;
-
-	spin_lock_irqsave(&ring->submit_lock, flags);
-	list_for_each_entry(submit, &ring->submits, node) {
-		if (fence_after(submit->seqno, fence))
-			break;
-
-		msm_update_fence(submit->ring->fctx,
-			submit->hw_fence->seqno);
-		dma_fence_signal(submit->hw_fence);
-	}
-	spin_unlock_irqrestore(&ring->submit_lock, flags);
-}
-
 #ifdef CONFIG_DEV_COREDUMP
 static ssize_t msm_gpu_devcoredump_read(char *buffer, loff_t offset,
 		size_t count, void *data, size_t datalen)
@@ -450,7 +432,7 @@ static void recover_worker(struct kthread_work *work)
 		if (ring == cur_ring)
 			fence++;
 
-		update_fences(gpu, ring, fence);
+		msm_update_fence(ring->fctx, fence);
 	}
 
 	if (msm_gpu_active(gpu)) {
@@ -753,7 +735,7 @@ void msm_gpu_retire(struct msm_gpu *gpu)
 	int i;
 
 	for (i = 0; i < gpu->nr_rings; i++)
-		update_fences(gpu, gpu->rb[i], gpu->rb[i]->memptrs->fence);
+		msm_update_fence(gpu->rb[i]->fctx, gpu->rb[i]->memptrs->fence);
 
 	kthread_queue_work(gpu->worker, &gpu->retire_work);
 	update_sw_cntrs(gpu);
-- 
2.36.1

[PATCH 1/2] drm/msm: Drop update_fences()

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

I noticed while looking at some traces, that we could miss calls to
msm_update_fence(), as the irq could have raced with retire_submits()
which could have already popped the last submit on a ring out of the
queue of in-flight submits.  But walking the list of submits in the
irq handler isn't really needed, as dma_fence_is_signaled() will dtrt.
So lets just drop it entirely.

Reported-by: Steev Klimaszewski <steev@kali.org>
Fixes: 95d1deb02a9c ("drm/msm/gem: Add fenced vma unpin")
Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/msm_gpu.c | 22 ++--------------------
 1 file changed, 2 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index e59a757578df..b61078f0cd0f 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -176,24 +176,6 @@ int msm_gpu_hw_init(struct msm_gpu *gpu)
 	return ret;
 }
 
-static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
-		uint32_t fence)
-{
-	struct msm_gem_submit *submit;
-	unsigned long flags;
-
-	spin_lock_irqsave(&ring->submit_lock, flags);
-	list_for_each_entry(submit, &ring->submits, node) {
-		if (fence_after(submit->seqno, fence))
-			break;
-
-		msm_update_fence(submit->ring->fctx,
-			submit->hw_fence->seqno);
-		dma_fence_signal(submit->hw_fence);
-	}
-	spin_unlock_irqrestore(&ring->submit_lock, flags);
-}
-
 #ifdef CONFIG_DEV_COREDUMP
 static ssize_t msm_gpu_devcoredump_read(char *buffer, loff_t offset,
 		size_t count, void *data, size_t datalen)
@@ -450,7 +432,7 @@ static void recover_worker(struct kthread_work *work)
 		if (ring == cur_ring)
 			fence++;
 
-		update_fences(gpu, ring, fence);
+		msm_update_fence(ring->fctx, fence);
 	}
 
 	if (msm_gpu_active(gpu)) {
@@ -753,7 +735,7 @@ void msm_gpu_retire(struct msm_gpu *gpu)
 	int i;
 
 	for (i = 0; i < gpu->nr_rings; i++)
-		update_fences(gpu, gpu->rb[i], gpu->rb[i]->memptrs->fence);
+		msm_update_fence(gpu->rb[i]->fctx, gpu->rb[i]->memptrs->fence);
 
 	kthread_queue_work(gpu->worker, &gpu->retire_work);
 	update_sw_cntrs(gpu);
-- 
2.36.1

[PATCH 2/2] drm/msm: Don't overwrite hw fence in hw_init

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

Prior to the last commit, this could result in setting the GPU
written fence value back to an older value, if we had missed
updating completed_fence prior to suspend.  This was mostly
harmless as the GPU would eventually overwrite it again with
the correct value.  But we should just not do this.  Instead
just leave a sanity check that the fence looks plausible (in
case the GPU scribbled on memory).

Reported-by: Steev Klimaszewski <steev@kali.org>
Fixes: 95d1deb02a9c ("drm/msm/gem: Add fenced vma unpin")
Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/adreno/adreno_gpu.c | 11 ++++++++---
 drivers/gpu/drm/msm/msm_gpu.c           |  2 +-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index e1aef4875e2f..dd044d557c7c 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -498,10 +498,15 @@ int adreno_hw_init(struct msm_gpu *gpu)
 
 		ring->cur = ring->start;
 		ring->next = ring->start;
-
-		/* reset completed fence seqno: */
-		ring->memptrs->fence = ring->fctx->completed_fence;
 		ring->memptrs->rptr = 0;
+
+		/* Detect and clean up an impossible fence, ie. if GPU managed
+		 * to scribble something invalid, we don't want that to confuse
+		 * us into mistakingly believing that submits have completed.
+		 */
+		if (fence_before(ring->fctx->last_fence, ring->memptrs->fence)) {
+			ring->memptrs->fence = ring->fctx->last_fence;
+		}
 	}
 
 	return 0;
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index b61078f0cd0f..8c00f9187c03 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -430,7 +430,7 @@ static void recover_worker(struct kthread_work *work)
 		 * one more to clear the faulting submit
 		 */
 		if (ring == cur_ring)
-			fence++;
+			ring->memptrs->fence = ++fence;
 
 		msm_update_fence(ring->fctx, fence);
 	}
-- 
2.36.1

[PATCH 2/2] drm/msm: Don't overwrite hw fence in hw_init

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

Prior to the last commit, this could result in setting the GPU
written fence value back to an older value, if we had missed
updating completed_fence prior to suspend.  This was mostly
harmless as the GPU would eventually overwrite it again with
the correct value.  But we should just not do this.  Instead
just leave a sanity check that the fence looks plausible (in
case the GPU scribbled on memory).

Reported-by: Steev Klimaszewski <steev@kali.org>
Fixes: 95d1deb02a9c ("drm/msm/gem: Add fenced vma unpin")
Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/adreno/adreno_gpu.c | 11 ++++++++---
 drivers/gpu/drm/msm/msm_gpu.c           |  2 +-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index e1aef4875e2f..dd044d557c7c 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -498,10 +498,15 @@ int adreno_hw_init(struct msm_gpu *gpu)
 
 		ring->cur = ring->start;
 		ring->next = ring->start;
-
-		/* reset completed fence seqno: */
-		ring->memptrs->fence = ring->fctx->completed_fence;
 		ring->memptrs->rptr = 0;
+
+		/* Detect and clean up an impossible fence, ie. if GPU managed
+		 * to scribble something invalid, we don't want that to confuse
+		 * us into mistakingly believing that submits have completed.
+		 */
+		if (fence_before(ring->fctx->last_fence, ring->memptrs->fence)) {
+			ring->memptrs->fence = ring->fctx->last_fence;
+		}
 	}
 
 	return 0;
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index b61078f0cd0f..8c00f9187c03 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -430,7 +430,7 @@ static void recover_worker(struct kthread_work *work)
 		 * one more to clear the faulting submit
 		 */
 		if (ring == cur_ring)
-			fence++;
+			ring->memptrs->fence = ++fence;
 
 		msm_update_fence(ring->fctx, fence);
 	}
-- 
2.36.1

Re: [PATCH 1/2] drm/msm: Drop update_fences()

[Steev Klimaszewski]

On 6/15/22 10:01 AM, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
>
> I noticed while looking at some traces, that we could miss calls to
> msm_update_fence(), as the irq could have raced with retire_submits()
> which could have already popped the last submit on a ring out of the
> queue of in-flight submits.  But walking the list of submits in the
> irq handler isn't really needed, as dma_fence_is_signaled() will dtrt.
> So lets just drop it entirely.
>
> Reported-by: Steev Klimaszewski <steev@kali.org>
> Fixes: 95d1deb02a9c ("drm/msm/gem: Add fenced vma unpin")
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>   drivers/gpu/drm/msm/msm_gpu.c | 22 ++--------------------
>   1 file changed, 2 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index e59a757578df..b61078f0cd0f 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -176,24 +176,6 @@ int msm_gpu_hw_init(struct msm_gpu *gpu)
>   	return ret;
>   }
>   
> -static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
> -		uint32_t fence)
> -{
> -	struct msm_gem_submit *submit;
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&ring->submit_lock, flags);
> -	list_for_each_entry(submit, &ring->submits, node) {
> -		if (fence_after(submit->seqno, fence))
> -			break;
> -
> -		msm_update_fence(submit->ring->fctx,
> -			submit->hw_fence->seqno);
> -		dma_fence_signal(submit->hw_fence);
> -	}
> -	spin_unlock_irqrestore(&ring->submit_lock, flags);
> -}
> -
>   #ifdef CONFIG_DEV_COREDUMP
>   static ssize_t msm_gpu_devcoredump_read(char *buffer, loff_t offset,
>   		size_t count, void *data, size_t datalen)
> @@ -450,7 +432,7 @@ static void recover_worker(struct kthread_work *work)
>   		if (ring == cur_ring)
>   			fence++;
>   
> -		update_fences(gpu, ring, fence);
> +		msm_update_fence(ring->fctx, fence);
>   	}
>   
>   	if (msm_gpu_active(gpu)) {
> @@ -753,7 +735,7 @@ void msm_gpu_retire(struct msm_gpu *gpu)
>   	int i;
>   
>   	for (i = 0; i < gpu->nr_rings; i++)
> -		update_fences(gpu, gpu->rb[i], gpu->rb[i]->memptrs->fence);
> +		msm_update_fence(gpu->rb[i]->fctx, gpu->rb[i]->memptrs->fence);
>   
>   	kthread_queue_work(gpu->worker, &gpu->retire_work);
>   	update_sw_cntrs(gpu);


Tested on the Lenovo Yoga C630

Tested-by: Steev Klimaszewski <steev@kali.org>

Re: [PATCH 1/2] drm/msm: Drop update_fences()

[Steev Klimaszewski]

On 6/15/22 10:01 AM, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
>
> I noticed while looking at some traces, that we could miss calls to
> msm_update_fence(), as the irq could have raced with retire_submits()
> which could have already popped the last submit on a ring out of the
> queue of in-flight submits.  But walking the list of submits in the
> irq handler isn't really needed, as dma_fence_is_signaled() will dtrt.
> So lets just drop it entirely.
>
> Reported-by: Steev Klimaszewski <steev@kali.org>
> Fixes: 95d1deb02a9c ("drm/msm/gem: Add fenced vma unpin")
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>   drivers/gpu/drm/msm/msm_gpu.c | 22 ++--------------------
>   1 file changed, 2 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index e59a757578df..b61078f0cd0f 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -176,24 +176,6 @@ int msm_gpu_hw_init(struct msm_gpu *gpu)
>   	return ret;
>   }
>   
> -static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
> -		uint32_t fence)
> -{
> -	struct msm_gem_submit *submit;
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&ring->submit_lock, flags);
> -	list_for_each_entry(submit, &ring->submits, node) {
> -		if (fence_after(submit->seqno, fence))
> -			break;
> -
> -		msm_update_fence(submit->ring->fctx,
> -			submit->hw_fence->seqno);
> -		dma_fence_signal(submit->hw_fence);
> -	}
> -	spin_unlock_irqrestore(&ring->submit_lock, flags);
> -}
> -
>   #ifdef CONFIG_DEV_COREDUMP
>   static ssize_t msm_gpu_devcoredump_read(char *buffer, loff_t offset,
>   		size_t count, void *data, size_t datalen)
> @@ -450,7 +432,7 @@ static void recover_worker(struct kthread_work *work)
>   		if (ring == cur_ring)
>   			fence++;
>   
> -		update_fences(gpu, ring, fence);
> +		msm_update_fence(ring->fctx, fence);
>   	}
>   
>   	if (msm_gpu_active(gpu)) {
> @@ -753,7 +735,7 @@ void msm_gpu_retire(struct msm_gpu *gpu)
>   	int i;
>   
>   	for (i = 0; i < gpu->nr_rings; i++)
> -		update_fences(gpu, gpu->rb[i], gpu->rb[i]->memptrs->fence);
> +		msm_update_fence(gpu->rb[i]->fctx, gpu->rb[i]->memptrs->fence);
>   
>   	kthread_queue_work(gpu->worker, &gpu->retire_work);
>   	update_sw_cntrs(gpu);


Tested on the Lenovo Yoga C630

Tested-by: Steev Klimaszewski <steev@kali.org>

Re: [PATCH 2/2] drm/msm: Don't overwrite hw fence in hw_init

[Steev Klimaszewski]

On 6/15/22 10:01 AM, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
>
> Prior to the last commit, this could result in setting the GPU
> written fence value back to an older value, if we had missed
> updating completed_fence prior to suspend.  This was mostly
> harmless as the GPU would eventually overwrite it again with
> the correct value.  But we should just not do this.  Instead
> just leave a sanity check that the fence looks plausible (in
> case the GPU scribbled on memory).
>
> Reported-by: Steev Klimaszewski <steev@kali.org>
> Fixes: 95d1deb02a9c ("drm/msm/gem: Add fenced vma unpin")
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>   drivers/gpu/drm/msm/adreno/adreno_gpu.c | 11 ++++++++---
>   drivers/gpu/drm/msm/msm_gpu.c           |  2 +-
>   2 files changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index e1aef4875e2f..dd044d557c7c 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -498,10 +498,15 @@ int adreno_hw_init(struct msm_gpu *gpu)
>   
>   		ring->cur = ring->start;
>   		ring->next = ring->start;
> -
> -		/* reset completed fence seqno: */
> -		ring->memptrs->fence = ring->fctx->completed_fence;
>   		ring->memptrs->rptr = 0;
> +
> +		/* Detect and clean up an impossible fence, ie. if GPU managed
> +		 * to scribble something invalid, we don't want that to confuse
> +		 * us into mistakingly believing that submits have completed.
> +		 */
> +		if (fence_before(ring->fctx->last_fence, ring->memptrs->fence)) {
> +			ring->memptrs->fence = ring->fctx->last_fence;
> +		}
>   	}
>   
>   	return 0;
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index b61078f0cd0f..8c00f9187c03 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -430,7 +430,7 @@ static void recover_worker(struct kthread_work *work)
>   		 * one more to clear the faulting submit
>   		 */
>   		if (ring == cur_ring)
> -			fence++;
> +			ring->memptrs->fence = ++fence;
>   
>   		msm_update_fence(ring->fctx, fence);
>   	}

Tested on the Lenovo Yoga C630

Tested-by: Steev Klimaszewski <steev@kali.org>

Re: [PATCH 2/2] drm/msm: Don't overwrite hw fence in hw_init

[Steev Klimaszewski]

On 6/15/22 10:01 AM, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
>
> Prior to the last commit, this could result in setting the GPU
> written fence value back to an older value, if we had missed
> updating completed_fence prior to suspend.  This was mostly
> harmless as the GPU would eventually overwrite it again with
> the correct value.  But we should just not do this.  Instead
> just leave a sanity check that the fence looks plausible (in
> case the GPU scribbled on memory).
>
> Reported-by: Steev Klimaszewski <steev@kali.org>
> Fixes: 95d1deb02a9c ("drm/msm/gem: Add fenced vma unpin")
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>   drivers/gpu/drm/msm/adreno/adreno_gpu.c | 11 ++++++++---
>   drivers/gpu/drm/msm/msm_gpu.c           |  2 +-
>   2 files changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index e1aef4875e2f..dd044d557c7c 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -498,10 +498,15 @@ int adreno_hw_init(struct msm_gpu *gpu)
>   
>   		ring->cur = ring->start;
>   		ring->next = ring->start;
> -
> -		/* reset completed fence seqno: */
> -		ring->memptrs->fence = ring->fctx->completed_fence;
>   		ring->memptrs->rptr = 0;
> +
> +		/* Detect and clean up an impossible fence, ie. if GPU managed
> +		 * to scribble something invalid, we don't want that to confuse
> +		 * us into mistakingly believing that submits have completed.
> +		 */
> +		if (fence_before(ring->fctx->last_fence, ring->memptrs->fence)) {
> +			ring->memptrs->fence = ring->fctx->last_fence;
> +		}
>   	}
>   
>   	return 0;
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index b61078f0cd0f..8c00f9187c03 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -430,7 +430,7 @@ static void recover_worker(struct kthread_work *work)
>   		 * one more to clear the faulting submit
>   		 */
>   		if (ring == cur_ring)
> -			fence++;
> +			ring->memptrs->fence = ++fence;
>   
>   		msm_update_fence(ring->fctx, fence);
>   	}

Tested on the Lenovo Yoga C630

Tested-by: Steev Klimaszewski <steev@kali.org>