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

[PATCH] 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")

Cc: stable@vger.kernel.org
Signed-off-by: Xiaolin Zhang <xiaolin.zhang@intel.com>
---
 drivers/gpu/drm/i915/gvt/scheduler.c | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index 8940fa8..89057c6 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 +1457,8 @@ 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 list_head *pos;
+	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 +1484,22 @@ 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(pos, q) {
+		last_workload = container_of(pos, struct intel_vgpu_workload,
+				list);
+		if (!last_workload)
+			continue;
+		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;
+		}
 	}
 
 	gvt_dbg_el("ring id %d begin a new workload\n", ring_id);
-- 
2.7.4

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

[Zhenyu Wang]

[-- Attachment #1: Type: text/plain, Size: 3607 bytes --]

On 2019.08.27 13:38:58 +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")
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Xiaolin Zhang <xiaolin.zhang@intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/scheduler.c | 31 ++++++++++++++++++-------------
>  1 file changed, 18 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
> index 8940fa8..89057c6 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 +1457,8 @@ 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 list_head *pos;
> +	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 +1484,22 @@ 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(pos, q) {
> +		last_workload = container_of(pos, struct intel_vgpu_workload,
> +				list);
> +		if (!last_workload)
> +			continue;

Just use list_for_each_entry() and to look up last uncompleted workload
should try to search backward, hopefully we can just fix it once.

> +		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;
> +		}
>  	}
>  
>  	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

-- 
Open Source Technology Center, Intel ltd.

$gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 195 bytes --]