[Intel-gfx] [PATCH v3 5/8] drm/i915: Add the display switch logic for vGPU in i915 driver

[Yu Zhang]

Display switch logic is added to notify the host side that
current vGPU have a valid surface to show. It does so by
writing the display_ready field in PV INFO page, and then
will be handled in the host side. This is useful to avoid
trickiness when the VM's framebuffer is being accessed in
the middle of VM modesetting, e.g. compositing the framebuffer
in the host side.

v2:
	- move the notification code outside the 'else' in load sequence
	- remove the notification code in intel_crtc_set_config()

Signed-off-by: Yu Zhang <yu.c.zhang at linux.intel.com>
Signed-off-by: Jike Song <jike.song at intel.com>
Signed-off-by: Zhiyuan Lv <zhiyuan.lv at intel.com>
---
 drivers/gpu/drm/i915/i915_dma.c  | 11 +++++++++++
 drivers/gpu/drm/i915/i915_vgpu.h |  7 +++++++
 2 files changed, 18 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 9a73533..06daa5c 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -36,6 +36,7 @@
 #include "intel_drv.h"
 #include <drm/i915_drm.h>
 #include "i915_drv.h"
+#include "i915_vgpu.h"
 #include "i915_trace.h"
 #include <linux/pci.h>
 #include <linux/console.h>
@@ -1780,6 +1781,16 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 		dev_priv->ums.mm_suspended = 1;
 	}
 
+	if (intel_vgpu_active(dev)) {
+		/*
+		 * Notify a valid surface after modesetting,
+		 * when running inside a VM.
+		 */
+		struct drm_i915_private *dev_priv = to_i915(dev);
+
+		I915_WRITE(vgtif_reg(display_ready), VGT_DRV_DISPLAY_READY);
+	}
+
 	i915_setup_sysfs(dev);
 
 	if (INTEL_INFO(dev)->num_pipes) {
diff --git a/drivers/gpu/drm/i915/i915_vgpu.h b/drivers/gpu/drm/i915/i915_vgpu.h
index f538b18..9d35fb8 100644
--- a/drivers/gpu/drm/i915/i915_vgpu.h
+++ b/drivers/gpu/drm/i915/i915_vgpu.h
@@ -80,6 +80,13 @@ struct vgt_if {
 #define vgtif_reg(x) \
 	(VGT_PVINFO_PAGE + (long)&((struct vgt_if *) NULL)->x)
 
+/* vGPU display status to be used by the host side */
+enum vgt_display_status {
+	VGT_DRV_DISPLAY_NOT_READY = 0,
+	VGT_DRV_DISPLAY_READY,  /* ready for display switch */
+};
+
+
 extern void i915_check_vgpu(struct drm_device *dev);
 extern int intel_vgt_balloon(struct drm_device *dev);
 extern void intel_vgt_deballoon(void);
-- 
1.9.1