[coreboot-gerrit] Change in coreboot[master]: cpu/x86/smm: Add support for long mode

[Patrick Rudolph (Code Review)]

Hello Kyösti Mälkki, Aaron Durbin, Stefan Reinauer, Paul Menzel, build bot (Jenkins), Raul Rangel, Patrick Georgi, ron minnich, Rudolf Marek, Lee Leahy, David Hendricks, Martin Roth,

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

https://review.coreboot.org/c/coreboot/+/35681

to look at the new patch set (#3).

Change subject: cpu/x86/smm: Add support for long mode
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cpu/x86/smm: Add support for long mode

Enable long mode in SMM handler.
x86_32 isn't affected from this change.

As the rsm instruction used to leave SMM doesn't restore MSR registers,
drop back to protected mode after running the smi_handler and restore
IA32_EFER MSR to previous value.

Tested on Qemu Q35.
Needs tests on real hardware.

Change-Id: I8bba4af4688c723fc079ae905dac95f57ea956f8
Signed-off-by: Patrick Rudolph 
---
M Documentation/arch/x86/index.md
M src/cpu/x86/smm/smmhandler.S
2 files changed, 94 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/81/35681/3