drm/i915: Fix GVT-g PVINFO version compatibility check

Current it's strictly checked if PVINFO version matches 1.0
for GVT-g i915 guest which doesn't help for compatibility at
all and forces GVT-g host can't extend PVINFO easily with version
bump for real compatibility check.

This fixes that to check minimal required PVINFO version instead.

v2:
- drop unneeded version macro
- use only major version for sanity check

v3:
- fix up PVInfo value with kernel type
- one indent fix
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Chuanxiao Dong <chuanxiao.dong@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: stable@vger.kernel.org # v4.10+
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170609074805.5101-1-zhenyuw@linux.intel.com

drivers/gpu/drm/i915/i915_pvinfo.h

@@ -36,10 +36,6 @@
 #define VGT_VERSION_MAJOR 1
 #define VGT_VERSION_MINOR 0
 
-#define INTEL_VGT_IF_VERSION_ENCODE(major, minor) ((major) << 16 | (minor))
-#define INTEL_VGT_IF_VERSION \
-	INTEL_VGT_IF_VERSION_ENCODE(VGT_VERSION_MAJOR, VGT_VERSION_MINOR)
-
 /*
  * notifications from guest to vgpu device model
  */
@@ -55,8 +51,8 @@ enum vgt_g2v_type {
 
 struct vgt_if {
 	u64 magic;		/* VGT_MAGIC */
-	uint16_t version_major;
-	uint16_t version_minor;
+	u16 version_major;
+	u16 version_minor;
 	u32 vgt_id;		/* ID of vGT instance */
 	u32 rsv1[12];		/* pad to offset 0x40 */
 	/*

drivers/gpu/drm/i915/i915_vgpu.c

@@ -60,8 +60,8 @@
  */
 void i915_check_vgpu(struct drm_i915_private *dev_priv)
 {
-	uint64_t magic;
-	uint32_t version;
+	u64 magic;
+	u16 version_major;
 
 	BUILD_BUG_ON(sizeof(struct vgt_if) != VGT_PVINFO_SIZE);
 
@@ -69,10 +69,8 @@ void i915_check_vgpu(struct drm_i915_private *dev_priv)
 	if (magic != VGT_MAGIC)
 		return;
 
-	version = INTEL_VGT_IF_VERSION_ENCODE(
-		__raw_i915_read16(dev_priv, vgtif_reg(version_major)),
-		__raw_i915_read16(dev_priv, vgtif_reg(version_minor)));
-	if (version != INTEL_VGT_IF_VERSION) {
+	version_major = __raw_i915_read16(dev_priv, vgtif_reg(version_major));
+	if (version_major < VGT_VERSION_MAJOR) {
 		DRM_INFO("VGT interface version mismatch!\n");
 		return;
 	}