x86/EFI: fix boot for pre-UEFI systems

efi/boot.c makes a call to QueryVariableInfo on all systems.  However,
as it is only promised for UEFI 2.0+ systems, pre-UEFI systems can
hang or crash on this call.  The below patch adds a version check, a
technique used in other parts of the Xen EFI codebase.

Signed-off-by: Eric Shelton <eshelton@pobox.com>
Check runtime services version instead of EFI version (while generally
they would be in sync, nothing requires them to be).

Signed-off-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/x86/efi/boot.c b/xen/arch/x86/efi/boot.c
index 117a5cbe43239ea101b463c22beffa292a2af1a0..9718bd7df9af58fb73a91c61cd01cda3a9e7e5b4 100644 (file)
--- a/xen/arch/x86/efi/boot.c
+++ b/xen/arch/x86/efi/boot.c
@@ -1241,12 +1241,14 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
     setup_efi_pci();
 
     /* Get snapshot of variable store parameters. */
-    status = efi_rs->QueryVariableInfo(EFI_VARIABLE_NON_VOLATILE |
+    status = (efi_rs->Hdr.Revision >> 16) >= 2 ?
+             efi_rs->QueryVariableInfo(EFI_VARIABLE_NON_VOLATILE |
                                        EFI_VARIABLE_BOOTSERVICE_ACCESS |
                                        EFI_VARIABLE_RUNTIME_ACCESS,
                                        &efi_boot_max_var_store_size,
                                        &efi_boot_remain_var_store_size,
-                                       &efi_boot_max_var_size);
+                                       &efi_boot_max_var_size) :
+             EFI_INCOMPATIBLE_VERSION;
     if ( EFI_ERROR(status) )
     {
         efi_boot_max_var_store_size = 0;