This MSR exists since Nehalem and is actively used by Linux, for instance,
to improve sampling efficiency.
Signed-off-by: Igor Druzhinin <igor.druzhi...@citrix.com>
---
New patch in v4 as suggested by Andrew.
---
xen/arch/x86/hvm/vmx/vmx.c | 7 +++++--
xen/include/asm-x86/msr-index.h | 6 +++++-
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 835b905..5a4ca35 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2915,14 +2915,16 @@ static const struct lbr_info {
}, nh_lbr[] = {
{ MSR_IA32_LASTINTFROMIP, 1 },
{ MSR_IA32_LASTINTTOIP, 1 },
- { MSR_C2_LASTBRANCH_TOS, 1 },
+ { MSR_NHL_LBR_SELECT, 1 },
+ { MSR_NHL_LASTBRANCH_TOS, 1 },
{ MSR_P4_LASTBRANCH_0_FROM_LIP, NUM_MSR_P4_LASTBRANCH_FROM_TO },
{ MSR_P4_LASTBRANCH_0_TO_LIP, NUM_MSR_P4_LASTBRANCH_FROM_TO },
{ 0, 0 }
}, sk_lbr[] = {
{ MSR_IA32_LASTINTFROMIP, 1 },
{ MSR_IA32_LASTINTTOIP, 1 },
- { MSR_SKL_LASTBRANCH_TOS, 1 },
+ { MSR_NHL_LBR_SELECT, 1 },
+ { MSR_NHL_LASTBRANCH_TOS, 1 },
{ MSR_SKL_LASTBRANCH_0_FROM_IP, NUM_MSR_SKL_LASTBRANCH },
{ MSR_SKL_LASTBRANCH_0_TO_IP, NUM_MSR_SKL_LASTBRANCH },
{ MSR_SKL_LASTBRANCH_0_INFO, NUM_MSR_SKL_LASTBRANCH },
@@ -2937,6 +2939,7 @@ static const struct lbr_info {
}, gm_lbr[] = {
{ MSR_IA32_LASTINTFROMIP, 1 },
{ MSR_IA32_LASTINTTOIP, 1 },
+ { MSR_GM_LBR_SELECT, 1 },
{ MSR_GM_LASTBRANCH_TOS, 1 },
{ MSR_GM_LASTBRANCH_0_FROM_IP, NUM_MSR_GM_LASTBRANCH_FROM_TO },
{ MSR_GM_LASTBRANCH_0_TO_IP, NUM_MSR_GM_LASTBRANCH_FROM_TO },
diff --git a/xen/include/asm-x86/msr-index.h b/xen/include/asm-x86/msr-index.h
index 43d26ef..25c4308 100644
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -606,14 +606,18 @@
#define NUM_MSR_C2_LASTBRANCH_FROM_TO 4
#define NUM_MSR_ATOM_LASTBRANCH_FROM_TO 8
+/* Nehalem (and newer) last-branch recording */
+#define MSR_NHL_LBR_SELECT 0x000001c8
+#define MSR_NHL_LASTBRANCH_TOS 0x000001c9
+
/* Skylake (and newer) last-branch recording */
-#define MSR_SKL_LASTBRANCH_TOS 0x000001c9
#define MSR_SKL_LASTBRANCH_0_FROM_IP 0x00000680
#define MSR_SKL_LASTBRANCH_0_TO_IP 0x000006c0
#define MSR_SKL_LASTBRANCH_0_INFO 0x00000dc0
#define NUM_MSR_SKL_LASTBRANCH 32
/* Goldmont last-branch recording */
+#define MSR_GM_LBR_SELECT 0x000001c8
#define MSR_GM_LASTBRANCH_TOS 0x000001c9
#define MSR_GM_LASTBRANCH_0_FROM_IP 0x00000680
#define MSR_GM_LASTBRANCH_0_TO_IP 0x000006c0
--
2.7.4
