[PATCH v2] drm/i915/gvt: refine vgpu gtt sync policy to reduce invalidate times

[Weinan Li]

Add delayed_update flag in gvt->gtt to indicate there is cached gtt entries
need to be flushed before vgpu workload submittion, then don't need to
trigger invalidate gtt every time gtt entry write, it can save time in vgpu
reset or vgpu has frequently gtt entries updating case.

v2 : use flag instead of atomic_t, code refine (Zhi)

Signed-off-by: Weinan Li <weinan.z.li at intel.com>
Cc: Zhi Wang <zhi.a.wang at intel.com>
Cc: Zhenyu Wang <zhenyuw at linux.intel.com>
---
 drivers/gpu/drm/i915/gvt/gtt.c | 20 ++++++++++++++++++--
 drivers/gpu/drm/i915/gvt/gtt.h |  1 +
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index 6fa9271..b4cb5ae 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -1293,6 +1293,15 @@ static int ppgtt_set_guest_page_oos(struct intel_vgpu *vgpu,
 	return intel_gvt_hypervisor_disable_page_track(vgpu, &gpt->track);
 }
 
+int intel_vgpu_flush_mm(struct intel_gvt *gvt, bool force)
+{
+	if (force || gvt->gtt.delayed_update) {
+		gvt->gtt.delayed_update = false;
+		gtt_invalidate(gvt->dev_priv);
+	}
+	return 0;
+}
+
 /**
  * intel_vgpu_sync_oos_pages - sync all the out-of-synced shadow for vGPU
  * @vgpu: a vGPU
@@ -1405,6 +1414,8 @@ int intel_vgpu_flush_post_shadow(struct intel_vgpu *vgpu)
 	unsigned long index;
 	int ret;
 
+	intel_vgpu_flush_mm(vgpu->gvt, false);
+
 	list_for_each_safe(pos, n, &vgpu->gtt.post_shadow_list_head) {
 		spt = container_of(pos, struct intel_vgpu_ppgtt_spt,
 				post_shadow_list);
@@ -1953,7 +1964,6 @@ static int emulate_gtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off,
 	/* the VM may configure the whole GM space when ballooning is used */
 	if (!vgpu_gmadr_is_valid(vgpu, gma))
 		return 0;
-
 	ggtt_get_guest_entry(ggtt_mm, &e, g_gtt_index);
 
 	memcpy((void *)&e.val64 + (off & (info->gtt_entry_size - 1)), p_data,
@@ -1975,8 +1985,14 @@ static int emulate_gtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off,
 	}
 
 	ggtt_set_shadow_entry(ggtt_mm, &m, g_gtt_index);
-	gtt_invalidate(gvt->dev_priv);
+
+	if (vgpu_gmadr_is_aperture(vgpu, gma))
+		gtt_invalidate(gvt->dev_priv);
+	else
+		gvt->gtt.delayed_update = true;
+
 	ggtt_set_guest_entry(ggtt_mm, &e, g_gtt_index);
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/i915/gvt/gtt.h b/drivers/gpu/drm/i915/gvt/gtt.h
index 416b2f8..f36f485 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.h
+++ b/drivers/gpu/drm/i915/gvt/gtt.h
@@ -88,6 +88,7 @@ struct intel_gvt_gtt {
 
 	struct page *scratch_page;
 	unsigned long scratch_mfn;
+	bool delayed_update;
 };
 
 enum {
-- 
1.9.1