[PATCH v10 1/2] x86/boot: Align mbi2.c stack to 16 bytes

[Frediano Ziglio <frediano.ziglio@xxxxxxxxx>]

Doing previous testing with an Alder Lake Intel machine with the
"x86/boot: Improve MBI2 structure check" commit test started to fail.
Removing the commit makes the tests succeed however there was not apparent
reason (looking at the code) for the failure.
So I instrumented code to output the structure and tested code with
this extracted data with and without the mentioned commit and results
were the same.
Compiled assembly code from lab was also fine beside not keeping
the 16-byte alignment for the stack.
Turning on stack alignment solve the problem on Alder Lake machine.

Fixes: eb21ce14d709 ('x86/boot: Rewrite EFI/MBI2 code partly in C')
Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Changes since v8:
- added "Fixes:" line;
- typo in commit message: Adler -> Alder;
- add ".init" to mbi2.o;
- reduce difference.

Changes since v9:
- minor commit message fix;
- added Reviewed-by.
---
 xen/arch/x86/efi/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/efi/Makefile b/xen/arch/x86/efi/Makefile
index 7e2b5c07de..c6678652fc 100644
--- a/xen/arch/x86/efi/Makefile
+++ b/xen/arch/x86/efi/Makefile
@@ -9,11 +9,11 @@ $(obj)/%.o: $(src)/%.ihex FORCE
 $(obj)/boot.init.o: $(obj)/buildid.o
 
 $(call cc-option-add,cflags-stack-boundary,CC,-mpreferred-stack-boundary=4)
-$(addprefix $(obj)/,$(EFIOBJ-y)): CFLAGS_stack_boundary := 
$(cflags-stack-boundary)
+$(addprefix $(obj)/,$(EFIOBJ-y) mbi2.init.o): CFLAGS_stack_boundary := 
$(cflags-stack-boundary)
 
 obj-y := common-stub.o stub.o
 obj-$(XEN_BUILD_EFI) := $(filter-out %.init.o,$(EFIOBJ-y))
 obj-bin-$(XEN_BUILD_EFI) := $(filter %.init.o,$(EFIOBJ-y))
-obj-bin-y += mbi2.o
+obj-bin-y += mbi2.init.o
 extra-$(XEN_BUILD_EFI) += buildid.o relocs-dummy.o
 nocov-$(XEN_BUILD_EFI) += stub.o
-- 
2.34.1