Patch by Andrew Lindh <andrew@netplex.net>
Patch code copied from Linux Kernel 5.17
Code tested on NUC 11 UEFI 64bit EFI-FB and Supermicro X9 UEFI 32bit EFI-FB

--- a/include/xen/interface/xen.h	2019-01-31 07:14:42.000000000 +0000
+++ b/include/xen/interface/xen.h	2022-04-22 17:41:38.053055993 +0000
@@ -737,6 +722,9 @@
 			uint32_t gbl_caps;
 			/* Mode attributes (offset 0x0, VESA command 0x4f01). */
 			uint16_t mode_attrs;
+			uint16_t pad;
+			/* high 32 bits of lfb_base */
+			uint32_t ext_lfb_base;
 		} vesa_lfb;
 	} u;
 };
--- a/arch/x86/xen/vga.c	2019-01-31 07:14:42.000000000 +0000
+++ b/arch/x86/xen/vga.c	2022-04-22 17:41:22.260930826 +0000
@@ -57,16 +57,20 @@
 		screen_info->rsvd_size = info->u.vesa_lfb.rsvd_size;
 		screen_info->rsvd_pos = info->u.vesa_lfb.rsvd_pos;
 
+		if (size >= offsetof(struct dom0_vga_console_info,
+				     u.vesa_lfb.ext_lfb_base)
+		    + sizeof(info->u.vesa_lfb.ext_lfb_base)
+		    && info->u.vesa_lfb.ext_lfb_base) {
+			screen_info->ext_lfb_base = info->u.vesa_lfb.ext_lfb_base;
+			screen_info->capabilities |= VIDEO_CAPABILITY_64BIT_BASE;
+		}
+
 		if (info->video_type == XEN_VGATYPE_EFI_LFB) {
 			screen_info->orig_video_isVGA = VIDEO_TYPE_EFI;
 			break;
 		}
 
 		if (size >= offsetof(struct dom0_vga_console_info,
-				     u.vesa_lfb.gbl_caps)
-		    + sizeof(info->u.vesa_lfb.gbl_caps))
-			screen_info->capabilities = info->u.vesa_lfb.gbl_caps;
-		if (size >= offsetof(struct dom0_vga_console_info,
 				     u.vesa_lfb.mode_attrs)
 		    + sizeof(info->u.vesa_lfb.mode_attrs))
 			screen_info->vesa_attributes = info->u.vesa_lfb.mode_attrs;