drm/i915/gvt: cleanup opregion memory allocation code

According to the spec, ACPI OpRegion must be placed at a physical address
below 4G. That is, for a vGPU it must be associated with a GPA below 4G,
but on host side, it doesn't matter where the backing pages actually are.
So when allocating pages from host, the GFP_DMA32 flag is unnecessary.

Also the allocation is from a sleepable context, so GFP_ATOMIC is also
unnecessary.

This patch also removes INTEL_GVT_OPREGION_PORDER and use get_order()
instead.
Signed-off-by: Jike Song <jike.song@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/opregion.c

@@ -36,9 +36,9 @@ static int init_vgpu_opregion(struct intel_vgpu *vgpu, u32 gpa)
 			vgpu->id))
 		return -EINVAL;
 
-	vgpu_opregion(vgpu)->va = (void *)__get_free_pages(GFP_ATOMIC |
-			GFP_DMA32 | __GFP_ZERO,
-			INTEL_GVT_OPREGION_PORDER);
+	vgpu_opregion(vgpu)->va = (void *)__get_free_pages(GFP_KERNEL |
+			__GFP_ZERO,
+			get_order(INTEL_GVT_OPREGION_SIZE));
 
 	if (!vgpu_opregion(vgpu)->va)
 		return -ENOMEM;
@@ -97,7 +97,7 @@ void intel_vgpu_clean_opregion(struct intel_vgpu *vgpu)
 	if (intel_gvt_host.hypervisor_type == INTEL_GVT_HYPERVISOR_XEN) {
 		map_vgpu_opregion(vgpu, false);
 		free_pages((unsigned long)vgpu_opregion(vgpu)->va,
-				INTEL_GVT_OPREGION_PORDER);
+				get_order(INTEL_GVT_OPREGION_SIZE));
 
 		vgpu_opregion(vgpu)->va = NULL;
 	}

drivers/gpu/drm/i915/gvt/reg.h

@@ -50,8 +50,7 @@
 #define INTEL_GVT_OPREGION_PARM                   0x204
 
 #define INTEL_GVT_OPREGION_PAGES	2
-#define INTEL_GVT_OPREGION_PORDER	1
-#define INTEL_GVT_OPREGION_SIZE		(2 * 4096)
+#define INTEL_GVT_OPREGION_SIZE		(INTEL_GVT_OPREGION_PAGES * PAGE_SIZE)
 
 #define VGT_SPRSTRIDE(pipe)	_PIPE(pipe, _SPRA_STRIDE, _PLANE_STRIDE_2_B)