[PATCH v2] drm/i915/gvt: update vgpu workload head pointer correctly

[PATCH v2] drm/i915/gvt: update vgpu workload head pointer correctly

[Xiaolin Zhang]

when creating a vGPU workload, the guest context head pointer should
be updated correctly by comparing with the exsiting workload in the
guest worklod queue including the current running context.

in some situation, there is a running context A and then received 2 new
vGPU workload context B and A. in the new workload context A, it's head
pointer should be updated with the running context A's tail.

Fixes: 09975b861aa0 ("drm/i915/execlists: Disable preemption under GVT")
Fixes: 22b7a426bbe1 ("drm/i915/execlists: Preempt-to-busy")

v2: walk through guest workload list in backward way.

Cc: stable@vger.kernel.org
Signed-off-by: Xiaolin Zhang <xiaolin.zhang@intel.com>
---
 drivers/gpu/drm/i915/gvt/scheduler.c | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index 8940fa8..166b998 100644
--- a/drivers/gpu/drm/i915/gvt/scheduler.c
+++ b/drivers/gpu/drm/i915/gvt/scheduler.c
@@ -1438,9 +1438,6 @@ static int prepare_mm(struct intel_vgpu_workload *workload)
 #define same_context(a, b) (((a)->context_id == (b)->context_id) && \
 		((a)->lrca == (b)->lrca))
 
-#define get_last_workload(q) \
-	(list_empty(q) ? NULL : container_of(q->prev, \
-	struct intel_vgpu_workload, list))
 /**
  * intel_vgpu_create_workload - create a vGPU workload
  * @vgpu: a vGPU
@@ -1460,7 +1457,7 @@ intel_vgpu_create_workload(struct intel_vgpu *vgpu, int ring_id,
 {
 	struct intel_vgpu_submission *s = &vgpu->submission;
 	struct list_head *q = workload_q_head(vgpu, ring_id);
-	struct intel_vgpu_workload *last_workload = get_last_workload(q);
+	struct intel_vgpu_workload *last_workload = NULL;
 	struct intel_vgpu_workload *workload = NULL;
 	struct drm_i915_private *dev_priv = vgpu->gvt->dev_priv;
 	u64 ring_context_gpa;
@@ -1486,15 +1483,20 @@ intel_vgpu_create_workload(struct intel_vgpu *vgpu, int ring_id,
 	head &= RB_HEAD_OFF_MASK;
 	tail &= RB_TAIL_OFF_MASK;
 
-	if (last_workload && same_context(&last_workload->ctx_desc, desc)) {
-		gvt_dbg_el("ring id %d cur workload == last\n", ring_id);
-		gvt_dbg_el("ctx head %x real head %lx\n", head,
-				last_workload->rb_tail);
-		/*
-		 * cannot use guest context head pointer here,
-		 * as it might not be updated at this time
-		 */
-		head = last_workload->rb_tail;
+	list_for_each_entry_reverse(last_workload, q, list) {
+
+		if (same_context(&last_workload->ctx_desc, desc)) {
+			gvt_dbg_el("ring id %d cur workload == last\n",
+					ring_id);
+			gvt_dbg_el("ctx head %x real head %lx\n", head,
+					last_workload->rb_tail);
+			/*
+			 * cannot use guest context head pointer here,
+			 * as it might not be updated at this time
+			 */
+			head = last_workload->rb_tail;
+			break;
+		}
 	}
 
 	gvt_dbg_el("ring id %d begin a new workload\n", ring_id);
-- 
2.7.4

Re: [PATCH v2] drm/i915/gvt: update vgpu workload head pointer correctly

[Zhenyu Wang]

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On 2019.08.27 16:39:23 +0800, Xiaolin Zhang wrote:
> when creating a vGPU workload, the guest context head pointer should
> be updated correctly by comparing with the exsiting workload in the
> guest worklod queue including the current running context.
> 
> in some situation, there is a running context A and then received 2 new
> vGPU workload context B and A. in the new workload context A, it's head
> pointer should be updated with the running context A's tail.
> 
> Fixes: 09975b861aa0 ("drm/i915/execlists: Disable preemption under GVT")
> Fixes: 22b7a426bbe1 ("drm/i915/execlists: Preempt-to-busy")
> 
> v2: walk through guest workload list in backward way.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Xiaolin Zhang <xiaolin.zhang@intel.com>
> ---

Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>

Thanks for the fix!

>  drivers/gpu/drm/i915/gvt/scheduler.c | 28 +++++++++++++++-------------
>  1 file changed, 15 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
> index 8940fa8..166b998 100644
> --- a/drivers/gpu/drm/i915/gvt/scheduler.c
> +++ b/drivers/gpu/drm/i915/gvt/scheduler.c
> @@ -1438,9 +1438,6 @@ static int prepare_mm(struct intel_vgpu_workload *workload)
>  #define same_context(a, b) (((a)->context_id == (b)->context_id) && \
>  		((a)->lrca == (b)->lrca))
>  
> -#define get_last_workload(q) \
> -	(list_empty(q) ? NULL : container_of(q->prev, \
> -	struct intel_vgpu_workload, list))
>  /**
>   * intel_vgpu_create_workload - create a vGPU workload
>   * @vgpu: a vGPU
> @@ -1460,7 +1457,7 @@ intel_vgpu_create_workload(struct intel_vgpu *vgpu, int ring_id,
>  {
>  	struct intel_vgpu_submission *s = &vgpu->submission;
>  	struct list_head *q = workload_q_head(vgpu, ring_id);
> -	struct intel_vgpu_workload *last_workload = get_last_workload(q);
> +	struct intel_vgpu_workload *last_workload = NULL;
>  	struct intel_vgpu_workload *workload = NULL;
>  	struct drm_i915_private *dev_priv = vgpu->gvt->dev_priv;
>  	u64 ring_context_gpa;
> @@ -1486,15 +1483,20 @@ intel_vgpu_create_workload(struct intel_vgpu *vgpu, int ring_id,
>  	head &= RB_HEAD_OFF_MASK;
>  	tail &= RB_TAIL_OFF_MASK;
>  
> -	if (last_workload && same_context(&last_workload->ctx_desc, desc)) {
> -		gvt_dbg_el("ring id %d cur workload == last\n", ring_id);
> -		gvt_dbg_el("ctx head %x real head %lx\n", head,
> -				last_workload->rb_tail);
> -		/*
> -		 * cannot use guest context head pointer here,
> -		 * as it might not be updated at this time
> -		 */
> -		head = last_workload->rb_tail;
> +	list_for_each_entry_reverse(last_workload, q, list) {
> +
> +		if (same_context(&last_workload->ctx_desc, desc)) {
> +			gvt_dbg_el("ring id %d cur workload == last\n",
> +					ring_id);
> +			gvt_dbg_el("ctx head %x real head %lx\n", head,
> +					last_workload->rb_tail);
> +			/*
> +			 * cannot use guest context head pointer here,
> +			 * as it might not be updated at this time
> +			 */
> +			head = last_workload->rb_tail;
> +			break;
> +		}
>  	}
>  
>  	gvt_dbg_el("ring id %d begin a new workload\n", ring_id);
> -- 
> 2.7.4
> 
> _______________________________________________
> intel-gvt-dev mailing list
> intel-gvt-dev@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gvt-dev

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