[PATCH v3] drm/i915/gvt: Fix PTE write flush for taking runtime pm properly

[Zhenyu Wang]

Make sure to take runtime pm when write PTE flush which ensure to
write to hw properly. This fixes warning during mdev/vgpu creation
which will do ggtt reset.

------------[ cut here ]------------
WARNING: CPU: 1 PID: 9375 at drivers/gpu/drm/i915/intel_drv.h:1748 fwtable_write32+0x1c2/0x1e0 [i915]
 RPM wakelock ref not held during HW access
Call Trace:
  ? dump_stack+0x5c/0x81
  ? __warn+0xbe/0xe0
  ? warn_slowpath_fmt+0x5a/0x80
  ? wake_up_klogd+0x37/0x40
  ? vprintk_emit+0x2ef/0x370
  ? fwtable_write32+0x1c2/0x1e0 [i915]
  ? gtt_set_entry64+0xbb/0xd0 [i915]
  ? intel_vgpu_reset_ggtt+0x88/0xf0 [i915]
  ? intel_vgpu_init_gtt+0xa5/0x4f0 [i915]
  ? intel_gvt_create_vgpu+0x1b5/0x250 [i915]
  ? kobject_put+0x1b/0x50
  ? intel_vgpu_create+0x4e/0x130 [kvmgt]
  ? mdev_device_create+0x186/0x2a0 [mdev]
  ? create_store+0xba/0xe0 [mdev]
  ? create_store+0xba/0xe0 [mdev]
  ? kernfs_fop_write+0x109/0x1a0
  ? kernfs_fop_write+0x109/0x1a0
  ? __vfs_write+0x33/0x160
  ? __fput+0x161/0x1d0
  ? vfs_write+0xb0/0x190
  ? SyS_write+0x52/0xc0
  ? exit_to_usermode_loop+0x7a/0xa0
  ? entry_SYSCALL_64_fastpath+0x1e/0xad

v2: remove unrelated oops info

v3: change to take runtime pm for ggtt reset instead of get/put for
    each pte write flush

Fixes: d650ac060237 ("drm/i915/gvt: reset the GGTT entry when vGPU created")
Cc: Ping Gao <ping.a.gao at intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
---
 drivers/gpu/drm/i915/gvt/gtt.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index 6da4e444e572..c6f0077f590d 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -2294,12 +2294,15 @@ void intel_gvt_clean_gtt(struct intel_gvt *gvt)
 void intel_vgpu_reset_ggtt(struct intel_vgpu *vgpu)
 {
 	struct intel_gvt *gvt = vgpu->gvt;
+	struct drm_i915_private *dev_priv = gvt->dev_priv;
 	struct intel_gvt_gtt_pte_ops *ops = vgpu->gvt->gtt.pte_ops;
 	u32 index;
 	u32 offset;
 	u32 num_entries;
 	struct intel_gvt_gtt_entry e;
 
+	intel_runtime_pm_get(dev_priv);
+
 	memset(&e, 0, sizeof(struct intel_gvt_gtt_entry));
 	e.type = GTT_TYPE_GGTT_PTE;
 	ops->set_pfn(&e, gvt->gtt.scratch_ggtt_mfn);
@@ -2314,6 +2317,8 @@ void intel_vgpu_reset_ggtt(struct intel_vgpu *vgpu)
 	num_entries = vgpu_hidden_sz(vgpu) >> PAGE_SHIFT;
 	for (offset = 0; offset < num_entries; offset++)
 		ops->set_entry(NULL, &e, index + offset, false, 0, vgpu);
+
+	intel_runtime_pm_put(dev_priv);
 }
 
 /**
-- 
2.11.0