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

[Xiong Zhang]

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);
 		}
 	}
 	spin_unlock_bh(&scheduler->mmio_context_lock);
-- 
2.7.4