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

[Zhenyu Wang]

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 at vger.kernel.org
> Signed-off-by: Xiaolin Zhang <xiaolin.zhang at 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 at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gvt-dev

-- 
Open Source Technology Center, Intel ltd.

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