[Intel-gfx] [PATCH v8 1/9] drm/i915: introduced vgpu pv capability

[Xiaolin Zhang]

pv capability for vgpu was introduced by pv_caps in struct
i915_virtual_gpu and a new pv_caps register for host GVT
was defined in struct vgt_if for vgpu pv optimization.

both of them are used to control different feature pv optimization
supported and implemented by both guest and host.

These fields are default zero, no any pv feature enabled.

it also adds VGT_CAPS_PV capability BIT for guest to check GVTg
can support PV feature or not.

v0: RFC, introudced enable_pvmmio module parameter.
v1: addressed RFC comment to remove enable_pvmmio module parameter
by pv capability check.
v2: rebase.
v3: distinct pv caps from guest and host. renamed enable_pvmmio to
pvmmio_caps which is used for host pv caps.
v4: consolidated all pv related functons into a single file i915_vgpu.c
and renamed pvmmio to pv_caps.
v5: rebase.
v6: rebase.
v7: rebase.

Signed-off-by: Xiaolin Zhang <xiaolin.zhang at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h    |  2 ++
 drivers/gpu/drm/i915/i915_pvinfo.h |  5 ++++-
 drivers/gpu/drm/i915/i915_vgpu.c   | 44 +++++++++++++++++++++++++++++++++++++-
 drivers/gpu/drm/i915/i915_vgpu.h   |  9 ++++++++
 4 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 0e44cc4..fa5dc47 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -93,6 +93,7 @@
 #include "i915_vma.h"
 
 #include "intel_gvt.h"
+#include "i915_pvinfo.h"
 
 /* General customization:
  */
@@ -1078,6 +1079,7 @@ struct i915_frontbuffer_tracking {
 struct i915_virtual_gpu {
 	bool active;
 	u32 caps;
+	u32 pv_caps;
 };
 
 /* used in computing the new watermarks state */
diff --git a/drivers/gpu/drm/i915/i915_pvinfo.h b/drivers/gpu/drm/i915/i915_pvinfo.h
index 683e97a..ad398b4 100644
--- a/drivers/gpu/drm/i915/i915_pvinfo.h
+++ b/drivers/gpu/drm/i915/i915_pvinfo.h
@@ -57,6 +57,7 @@ enum vgt_g2v_type {
 #define VGT_CAPS_FULL_PPGTT		BIT(2)
 #define VGT_CAPS_HWSP_EMULATION		BIT(3)
 #define VGT_CAPS_HUGE_GTT		BIT(4)
+#define VGT_CAPS_PV		BIT(5)
 
 struct vgt_if {
 	u64 magic;		/* VGT_MAGIC */
@@ -109,7 +110,9 @@ struct vgt_if {
 	u32 execlist_context_descriptor_lo;
 	u32 execlist_context_descriptor_hi;
 
-	u32  rsv7[0x200 - 24];    /* pad to one page */
+	u32 pv_caps;
+
+	u32  rsv7[0x200 - 25];    /* pad to one page */
 } __packed;
 
 #define vgtif_offset(x) (offsetof(struct vgt_if, x))
diff --git a/drivers/gpu/drm/i915/i915_vgpu.c b/drivers/gpu/drm/i915/i915_vgpu.c
index dbd1fa3..9b37dd1 100644
--- a/drivers/gpu/drm/i915/i915_vgpu.c
+++ b/drivers/gpu/drm/i915/i915_vgpu.c
@@ -95,7 +95,14 @@ void i915_detect_vgpu(struct drm_i915_private *dev_priv)
 	dev_priv->vgpu.caps = readl(shared_area + vgtif_offset(vgt_caps));
 
 	dev_priv->vgpu.active = true;
-	DRM_INFO("Virtual GPU for Intel GVT-g detected.\n");
+
+	if (!intel_vgpu_check_pv_caps(dev_priv, shared_area)) {
+		DRM_INFO("Virtual GPU for Intel GVT-g detected.\n");
+		return;
+	}
+
+	DRM_INFO("Virtual GPU for Intel GVT-g detected with pv_caps 0x%x.\n",
+			dev_priv->vgpu.pv_caps);
 
 out:
 	pci_iounmap(pdev, shared_area);
@@ -297,3 +304,38 @@ int intel_vgt_balloon(struct i915_ggtt *ggtt)
 	DRM_ERROR("VGT balloon fail\n");
 	return ret;
 }
+
+/*
+ * i915 vgpu PV support for Linux
+ */
+
+/**
+ * intel_vgpu_check_pv_caps - detect virtual GPU PV capabilities
+ * @dev_priv: i915 device private
+ *
+ * This function is called at the initialization stage, to detect VGPU
+ * PV capabilities
+ *
+ * If guest wants to enable pv_caps, it needs to config it explicitly
+ * through vgt_if interface from gvt layer.
+ */
+bool intel_vgpu_check_pv_caps(struct drm_i915_private *dev_priv,
+		void __iomem *shared_area)
+{
+	u32 gvt_pvcaps;
+	u32 pvcaps = 0;
+
+	if (!intel_vgpu_has_pv_caps(dev_priv))
+		return false;
+
+	/* PV capability negotiation between PV guest and GVT */
+	gvt_pvcaps = readl(shared_area + vgtif_offset(pv_caps));
+	pvcaps = dev_priv->vgpu.pv_caps & gvt_pvcaps;
+	dev_priv->vgpu.pv_caps = pvcaps;
+	writel(pvcaps, shared_area + vgtif_offset(pv_caps));
+
+	if (!pvcaps)
+		return false;
+
+	return true;
+}
diff --git a/drivers/gpu/drm/i915/i915_vgpu.h b/drivers/gpu/drm/i915/i915_vgpu.h
index 8b3663d..bbe56b5 100644
--- a/drivers/gpu/drm/i915/i915_vgpu.h
+++ b/drivers/gpu/drm/i915/i915_vgpu.h
@@ -43,7 +43,16 @@
 	return dev_priv->vgpu.caps & VGT_CAPS_HUGE_GTT;
 }
 
+static inline bool
+intel_vgpu_has_pv_caps(struct drm_i915_private *dev_priv)
+{
+	return dev_priv->vgpu.caps & VGT_CAPS_PV;
+}
+
 int intel_vgt_balloon(struct i915_ggtt *ggtt);
 void intel_vgt_deballoon(struct i915_ggtt *ggtt);
 
+/* i915 vgpu pv related functions */
+bool intel_vgpu_check_pv_caps(struct drm_i915_private *dev_priv,
+		void __iomem *shared_area);
 #endif /* _I915_VGPU_H_ */
-- 
1.8.3.1