[PATCH V3] drm/i915/gvt: save RING_HEAD into vreg when vgpu switched out

[Xiaolin Zhang]

to save RING_HEAD into vgpu reg when vgpu switched out and report
it's value back to guest.

v3: save RING HEAD/TAIL vgpu reg in save_ring_hw_state. (Zhenyu Wang)
v2: save RING_TAIL as well during vgpu mmio switch to meet ring_is_idle
condition. (Fred Gao)
v1: based on input from Weinan. (Weinan Li)

Fixes: 519a019491b8 ("drm/i915/hangcheck: Replace hangcheck.seqno with RING_HEAD")

Signed-off-by: Xiaolin Zhang <xiaolin.zhang at intel.com>
---
 drivers/gpu/drm/i915/gvt/scheduler.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index 38897d2..353b4d0 100644
--- a/drivers/gpu/drm/i915/gvt/scheduler.c
+++ b/drivers/gpu/drm/i915/gvt/scheduler.c
@@ -218,6 +218,10 @@ static void save_ring_hw_state(struct intel_vgpu *vgpu, int ring_id)
 	vgpu_vreg(vgpu, i915_mmio_reg_offset(reg)) = I915_READ_FW(reg);
 	reg = RING_ACTHD_UDW(ring_base);
 	vgpu_vreg(vgpu, i915_mmio_reg_offset(reg)) = I915_READ_FW(reg);
+	reg = RING_HEAD(ring_base);
+	vgpu_vreg(vgpu, i915_mmio_reg_offset(reg)) = I915_READ_FW(reg);
+	reg = RING_TAIL(ring_base);
+	vgpu_vreg(vgpu, i915_mmio_reg_offset(reg)) = I915_READ_FW(reg);
 }
 
 static int shadow_context_status_change(struct notifier_block *nb,
-- 
2.7.4