[M] Change in coreboot[master]: cpu/x86/smm: Move setting up 64bit mode earlier

[Arthur Heymans (Code Review)]

Hello build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/68897

to look at the new patch set (#4).

Change subject: cpu/x86/smm: Move setting up 64bit mode earlier
......................................................................

cpu/x86/smm: Move setting up 64bit mode earlier

Now there is no need to do it that late in the smm stub. Since we don't
need the stack to save EFER MSR anymore.

This also removes the need exit back to protected mode for the fxrstor
instruction. A further advantage is that all XMM regs (remember that
there are more in long mode) are now properly saved.

TESTED with qemu: both 32 and 64bit smihandler work fine.

Change-Id: Ie247d6fba0dbc953a810038465f1e0d42ca171cf
Signed-off-by: Arthur Heymans 
---
M src/cpu/x86/smm/smm_stub.S
1 file changed, 44 insertions(+), 23 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/97/68897/4