[Intel-gfx] [PATCH v2 2/5] drm/i915: get ready of memory for pvmmio

[Xiaolin Zhang]

To enable pvmmio feature, we need to prepare one 4K shared page
which will be accessed by both guest and backend i915 driver.

guest i915 allocate one page memory and then the guest physical address is
passed to backend i915 driver through PVINFO register so that backend i915
driver can access this shared page without hypeviser trap cost for shared
data exchagne via hyperviser read_gpa functionality.

v0: RFC
v1: addressed RFC comment to move both shared_page_lock and shared_page
to i915_virtual_gpu structure
v2: packed i915_virtual_gpu structure

Cc: Zhenyu Wang <zhenyuw at linux.intel.com>
Cc: Zhi Wang <zhi.a.wang at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: He, Min <min.he at intel.com>
Cc: Jiang, Fei <fei.jiang at intel.com>
Cc: Gong, Zhipeng <zhipeng.gong at intel.com>
Cc: Yuan, Hang <hang.yuan at intel.com>
Cc: Zhiyuan Lv <zhiyuan.lv at intel.com>
Signed-off-by: Xiaolin Zhang <xiaolin.zhang at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c    |  2 ++
 drivers/gpu/drm/i915/i915_drv.h    |  4 +++-
 drivers/gpu/drm/i915/i915_pvinfo.h | 24 +++++++++++++++++++++++-
 drivers/gpu/drm/i915/i915_vgpu.c   | 24 +++++++++++++++++++++++-
 4 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index baac35f..557ab67 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -987,6 +987,8 @@ static void i915_mmio_cleanup(struct drm_i915_private *dev_priv)
 
 	intel_teardown_mchbar(dev_priv);
 	pci_iounmap(pdev, dev_priv->regs);
+	if (intel_vgpu_active(dev_priv) && dev_priv->vgpu.shared_page)
+		free_page((unsigned long)dev_priv->vgpu.shared_page);
 }
 
 /**
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 7b2d7cb..d7a972f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1345,7 +1345,9 @@ struct i915_virtual_gpu {
 	bool active;
 	u32 caps;
 	u32 pv_caps;
-};
+	spinlock_t shared_page_lock;
+	struct gvt_shared_page *shared_page;
+} __packed;
 
 /* used in computing the new watermarks state */
 struct intel_wm_config {
diff --git a/drivers/gpu/drm/i915/i915_pvinfo.h b/drivers/gpu/drm/i915/i915_pvinfo.h
index 26709e8..179d558 100644
--- a/drivers/gpu/drm/i915/i915_pvinfo.h
+++ b/drivers/gpu/drm/i915/i915_pvinfo.h
@@ -49,6 +49,24 @@ enum vgt_g2v_type {
 	VGT_G2V_MAX,
 };
 
+struct pv_ppgtt_update {
+	u64 pdp;
+	u64 start;
+	u64 length;
+	u32 cache_level;
+};
+
+/*
+ * shared page(4KB) between gvt and VM, could be allocated by guest driver
+ * or a fixed location in PCI bar 0 region
+ */
+struct gvt_shared_page {
+	u32 elsp_data[4];
+	u32 reg_addr;
+	u32 disable_irq;
+	struct pv_ppgtt_update pv_ppgtt;
+};
+
 #define VGPU_PVMMIO(vgpu) vgpu_vreg_t(vgpu, vgtif_reg(enable_pvmmio))
 
 /*
@@ -121,8 +139,12 @@ struct vgt_if {
 	u32 execlist_context_descriptor_lo;
 	u32 execlist_context_descriptor_hi;
 	u32 enable_pvmmio;
+	struct {
+		u32 lo;
+		u32 hi;
+	} shared_page_gpa;
 
-	u32  rsv7[0x200 - 25];    /* pad to one page */
+	u32  rsv7[0x200 - 27];    /* pad to one page */
 } __packed;
 
 #define vgtif_reg(x) \
diff --git a/drivers/gpu/drm/i915/i915_vgpu.c b/drivers/gpu/drm/i915/i915_vgpu.c
index 907bbd2..cb409d5 100644
--- a/drivers/gpu/drm/i915/i915_vgpu.c
+++ b/drivers/gpu/drm/i915/i915_vgpu.c
@@ -62,6 +62,7 @@ void i915_check_vgpu(struct drm_i915_private *dev_priv)
 {
 	u64 magic;
 	u16 version_major;
+	u64 gpa;
 
 	BUILD_BUG_ON(sizeof(struct vgt_if) != VGT_PVINFO_SIZE);
 
@@ -91,7 +92,28 @@ void i915_check_vgpu(struct drm_i915_private *dev_priv)
 			dev_priv->vgpu.pv_caps);
 	dev_priv->vgpu.pv_caps = __raw_i915_read32(dev_priv,
 			vgtif_reg(enable_pvmmio));
-
+	if (intel_vgpu_active(dev_priv) && dev_priv->vgpu.pv_caps) {
+		dev_priv->vgpu.shared_page =  (struct gvt_shared_page *)
+				get_zeroed_page(GFP_KERNEL);
+		if (!dev_priv->vgpu.shared_page) {
+			DRM_ERROR("out of memory for shared page memory\n");
+			return;
+		}
+		gpa = __pa(dev_priv->vgpu.shared_page);
+		__raw_i915_write32(dev_priv, vgtif_reg(shared_page_gpa.lo),
+				lower_32_bits(gpa));
+		__raw_i915_write32(dev_priv, vgtif_reg(shared_page_gpa.hi),
+				upper_32_bits(gpa));
+		if (gpa != __raw_i915_read64(dev_priv,
+				vgtif_reg(shared_page_gpa))) {
+			DRM_ERROR("vgpu: passed shared_page_gpa failed\n");
+			free_page((unsigned long)dev_priv->vgpu.shared_page);
+			dev_priv->vgpu.pv_caps = 0;
+			return;
+		}
+		spin_lock_init(&dev_priv->vgpu.shared_page_lock);
+		DRM_INFO("VGPU shared page enabled\n");
+	}
 	DRM_INFO("Virtual GPU for Intel GVT-g detected with pvmmio 0x%x\n",
 			dev_priv->vgpu.pv_caps);
 }
-- 
2.7.4