[PATCH] drm/i915/gvt: Add runtime_pm_get/put around gvt_switch_mmio at vgpu destroy

[Zhenyu Wang]

On 2018.02.02 06:55:22 +0800, Xiong Zhang wrote:
> If user continuously create vgpu, boot guest, shoutdown guest and destroy
> vgpu from remote, the following calltrace exists in dmesg sometimes:
> [ 6412.954721] RPM wakelock ref not held during HW access
> [ 6412.954795] WARNING: CPU: 7 PID: 11941 at linux/drivers/gpu/drm/i915/intel_drv.h:1800 intel_uncore_forcewake_get.part.7+0x96/0xa0 [i915]
> [ 6412.954915] Call Trace:
> [ 6412.954951] intel_uncore_forcewake_get+0x18/0x20 [i915]
> [ 6412.954989] intel_gvt_switch_mmio+0x8e/0x770 [i915]
> [ 6412.954996] ? __slab_free+0x14d/0x2c0
> [ 6412.955001] ? __slab_free+0x14d/0x2c0
> [ 6412.955006] ? __slab_free+0x14d/0x2c0
> [ 6412.955041] intel_vgpu_stop_schedule+0x92/0xd0 [i915]
> [ 6412.955073] intel_gvt_deactivate_vgpu+0x48/0x60 [i915]
> [ 6412.955078] __intel_vgpu_release+0x55/0x260 [kvmgt]
> 
> when this happens, gvt_switch_mmio is called at vgpu destroy, host i915 is
> idle and doesn't hold RPM wakelock, IGD is in powersave mode, but
> gvt_switch_mmio require igd power on to access register, so
> intel_runtime_pm_get should be added to make sure igd power on before
> gvt_switch_mmio at vgpu destroy.
> 
> Signed-off-by: Xiong Zhang <xiong.y.zhang at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/sched_policy.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/sched_policy.c b/drivers/gpu/drm/i915/gvt/sched_policy.c
> index cc1ce36..a714064 100644
> --- a/drivers/gpu/drm/i915/gvt/sched_policy.c
> +++ b/drivers/gpu/drm/i915/gvt/sched_policy.c
> @@ -416,8 +416,10 @@ void intel_vgpu_stop_schedule(struct intel_vgpu *vgpu)
>  	spin_lock_bh(&scheduler->mmio_context_lock);
>  	for (ring_id = 0; ring_id < I915_NUM_ENGINES; ring_id++) {
>  		if (scheduler->engine_owner[ring_id] == vgpu) {
> +			intel_runtime_pm_get(vgpu->gvt->dev_priv);
>  			intel_gvt_switch_mmio(vgpu, NULL, ring_id);
>  			scheduler->engine_owner[ring_id] = NULL;
> +			intel_runtime_pm_put(vgpu->gvt->dev_priv);
>  		}

Could we do that in switch mmio as always required?

>  	}
>  	spin_unlock_bh(&scheduler->mmio_context_lock);
> -- 
> 2.7.4
> 
> _______________________________________________
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> intel-gvt-dev at lists.freedesktop.org
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