drm/i915: replace X86_FEATURE_PAT with pat_enabled()

PAT can be disabled on boot with "nopat" in the command line. Replace
one x86-ism with another, which is slightly more correct to prepare for
supporting other architectures.

Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211202003048.1015511-1-lucas.demarchi@intel.com

drivers/gpu/drm/i915/gem/i915_gem_mman.c

@@ -72,7 +72,7 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
 	if (args->flags & ~(I915_MMAP_WC))
 		return -EINVAL;
 
-	if (args->flags & I915_MMAP_WC && !boot_cpu_has(X86_FEATURE_PAT))
+	if (args->flags & I915_MMAP_WC && !pat_enabled())
 		return -ENODEV;
 
 	obj = i915_gem_object_lookup(file, args->handle);
@@ -736,7 +736,7 @@ i915_gem_dumb_mmap_offset(struct drm_file *file,
 
 	if (HAS_LMEM(to_i915(dev)))
 		mmap_type = I915_MMAP_TYPE_FIXED;
-	else if (boot_cpu_has(X86_FEATURE_PAT))
+	else if (pat_enabled())
 		mmap_type = I915_MMAP_TYPE_WC;
 	else if (!i915_ggtt_has_aperture(&to_i915(dev)->ggtt))
 		return -ENODEV;
@@ -792,7 +792,7 @@ i915_gem_mmap_offset_ioctl(struct drm_device *dev, void *data,
 		break;
 
 	case I915_MMAP_OFFSET_WC:
-		if (!boot_cpu_has(X86_FEATURE_PAT))
+		if (!pat_enabled())
 			return -ENODEV;
 		type = I915_MMAP_TYPE_WC;
 		break;
@@ -802,7 +802,7 @@ i915_gem_mmap_offset_ioctl(struct drm_device *dev, void *data,
 		break;
 
 	case I915_MMAP_OFFSET_UC:
-		if (!boot_cpu_has(X86_FEATURE_PAT))
+		if (!pat_enabled())
 			return -ENODEV;
 		type = I915_MMAP_TYPE_UC;
 		break;

drivers/gpu/drm/i915/gem/i915_gem_pages.c

@@ -424,8 +424,7 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
 			goto err_unpin;
 		}
 
-		if (GEM_WARN_ON(type == I915_MAP_WC &&
-				!static_cpu_has(X86_FEATURE_PAT)))
+		if (GEM_WARN_ON(type == I915_MAP_WC && !pat_enabled()))
 			ptr = ERR_PTR(-ENODEV);
 		else if (i915_gem_object_has_struct_page(obj))
 			ptr = i915_gem_object_map_page(obj, type);