[coreboot-gerrit] Change in coreboot[master]: [TEST]cpu/x86/mp_init: Park APs in C7

[Nico Huber (Code Review)]

Nico Huber has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/37007 )

Change subject: [TEST]cpu/x86/mp_init: Park APs in C7
......................................................................

[TEST]cpu/x86/mp_init: Park APs in C7

Change-Id: I960871450407ade6e8f18e69921ce74aa7fbca24
Signed-off-by: Nico Huber 
---
M src/cpu/x86/mp_init.c
1 file changed, 16 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/07/37007/1

diff --git a/src/cpu/x86/mp_init.c b/src/cpu/x86/mp_init.c
index 29ae3de..16435fc 100644
--- a/src/cpu/x86/mp_init.c
+++ b/src/cpu/x86/mp_init.c
@@ -184,7 +184,22 @@

static void park_this_cpu(void *unused)
 {
-	stop_this_cpu();
+	/* need some address of write-back memory, use AP's stack for now */
+	const struct cpu_info *const info = cpu_info();
+	const uintptr_t stack_bottom = ALIGN_DOWN((uintptr_t)&_estack, CONFIG_STACK_SIZE)
+					- (info->index + 1) * CONFIG_STACK_SIZE;
+	asm volatile(
+		"xor %%ecx, %%ecx\n\t"
+		"xor %%edx, %%edx\n"
+		"__monitor:\n\t"
+		"mov %0, %%eax\n\t"
+		"monitor\n\t"
+		"mov $0x60, %%eax\n\t"
+		"mwait\n\t"
+		"jmp __monitor\n\t"
+		:
+		: "r" (stack_bottom)
+		: "eax", "ecx", "edx");
 }

/* By the time APs call ap_init() caching has been setup, and microcode has