Change in coreboot[master]: [WIP]cpu/x86/smm: Add a Kconfig option to disable smihandler

[Arthur Heymans (Code Review)]

Arthur Heymans has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/51377 )

Change subject: [WIP]cpu/x86/smm: Add a Kconfig option to disable smihandler
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[WIP]cpu/x86/smm: Add a Kconfig option to disable smihandler

Change-Id: Ia3834897d909c0edcf52ebace19586ee5038748d
Signed-off-by: Arthur Heymans 
---
M src/cpu/x86/Kconfig
M src/cpu/x86/smm/smm_module_handler.c
2 files changed, 11 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/77/51377/1

diff --git a/src/cpu/x86/Kconfig b/src/cpu/x86/Kconfig
index b3a16bc..4a6b221 100644
--- a/src/cpu/x86/Kconfig
+++ b/src/cpu/x86/Kconfig
@@ -96,6 +96,13 @@
    default y
    depends on !(NO_SMM || SMM_ASEG)

+config X86_DISABLE_SMIHANDLER
+	bool "Disable smihandler"
+	default n
+	help
+	  This sets up an smihandler that never sets EOS, which effectively
+	  disables SMM.
+
 if SMM_TSEG

config SMM_MODULE_HEAP_SIZE
diff --git a/src/cpu/x86/smm/smm_module_handler.c b/src/cpu/x86/smm/smm_module_handler.c
index 8532d59..e61a28d 100644
--- a/src/cpu/x86/smm/smm_module_handler.c
+++ b/src/cpu/x86/smm/smm_module_handler.c
@@ -132,6 +132,10 @@
    cpu = p->cpu;
    expected_canary = (uintptr_t)p->canary;

+	/* As we don't set EOS, no further SMI# will be generated */
+	if (CONFIG(X86_DISABLE_SMIHANDLER))
+		return;
+
    /* Make sure to set the global runtime. It's OK to race as the value
     * will be the same across CPUs as well as multiple SMIs. */
    if (smm_runtime == NULL) {