efi: dmi: add support for SMBIOS 3.0 UEFI configuration table

This adds support to the UEFI side for detecting the presence of
a SMBIOS 3.0 64-bit entry point. This allows the actual SMBIOS
structure table to reside at a physical offset over 4 GB, which
cannot be supported by the legacy SMBIOS 32-bit entry point.

Since the firmware can legally provide both entry points, store
the SMBIOS 3.0 entry point in a separate variable, and let the
DMI decoding layer decide which one will be used.

Tested-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Acked-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

drivers/xen/efi.c

@@ -294,6 +294,7 @@ static const struct efi efi_xen __initconst = {
 	.acpi                     = EFI_INVALID_TABLE_ADDR,
 	.acpi20                   = EFI_INVALID_TABLE_ADDR,
 	.smbios                   = EFI_INVALID_TABLE_ADDR,
+	.smbios3                  = EFI_INVALID_TABLE_ADDR,
 	.sal_systab               = EFI_INVALID_TABLE_ADDR,
 	.boot_info                = EFI_INVALID_TABLE_ADDR,
 	.hcdp                     = EFI_INVALID_TABLE_ADDR,