[coreboot-gerrit] [S] Change in coreboot[main]: [UNTESTED]cpu/amd: Lock down paging and EFER in SMM

[Arthur Heymans (Code Review)]

Arthur Heymans has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/80187?usp=email )

Change subject: [UNTESTED]cpu/amd: Lock down paging and EFER in SMM
......................................................................

[UNTESTED]cpu/amd: Lock down paging and EFER in SMM

Changing page tables or the value of EFER in SMM is undesirable in the
coreboot use case.

Signed-off-by: Arthur Heymans 
Change-Id: I96fb75759444e9c2afa3bec719045ece1ec2daf8
---
M src/cpu/x86/smm/smm_stub.S
M src/include/cpu/amd/msr.h
2 files changed, 17 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/87/80187/1

diff --git a/src/cpu/x86/smm/smm_stub.S b/src/cpu/x86/smm/smm_stub.S
index f97ab59..cd01611 100644
--- a/src/cpu/x86/smm/smm_stub.S
+++ b/src/cpu/x86/smm/smm_stub.S
@@ -9,6 +9,7 @@
  * found in smm.h.
  */

+#include <cpu/amd/msr.h>
 #include <cpu/x86/cr.h>
 #include <cpu/x86/msr.h>
 #include <cpu/x86/lapic_def.h>
@@ -196,9 +197,15 @@
    mov	%ecx, %edi
    /* entry64.inc preserves ebx, esi, edi, ebp */
 #include <cpu/x86/64bit/entry64.inc>
+#if CONFIG(CPU_AMD_PI) || CONFIG(SOC_AMD_COMMON)
+	/* Lock down paging */
+	movl	$HWCR_MSR, %ecx
+	rdmsr
+	or	$SMM_PGCFG_LOCK, %eax
+	wrmsr
+#endif
    mov	%edi, %ecx

-
    push	%rbx /* uintptr_t *canary */
    push	%rcx /* size_t cpu */

@@ -211,6 +218,14 @@
    push	%ebx /* uintptr_t *canary */
    push	%ecx /* size_t cpu */
    push	%esp /* smm_module_params *arg (allocated on stack). */
+
+#if CONFIG(CPU_AMD_PI) || CONFIG(SOC_AMD_COMMON)
+	/* Lock down paging */
+	movl	$HWCR_MSR, %ecx
+	rdmsr
+	or	$SMM_PGCFG_LOCK, %eax
+	wrmsr
+#endif
    mov	c_handler, %eax
    call	*%eax
 #endif
diff --git a/src/include/cpu/amd/msr.h b/src/include/cpu/amd/msr.h
index 3f7febc..8ad7a2f 100644
--- a/src/include/cpu/amd/msr.h
+++ b/src/include/cpu/amd/msr.h
@@ -16,6 +16,7 @@
 #define FS_Base				0xC0000100
 #define HWCR_MSR			0xC0010015
 #define  SMM_LOCK			(1 << 0)
+#define  SMM_PGCFG_LOCK			(1 << 3)
 #define NB_CFG_MSR			0xC001001f
 #define FidVidStatus			0xC0010042
 #define MC0_CTL_MASK			0xC0010044