The lbr_ctl variable in the vmcb control area is used to enable or
disable Last Branch Record (LBR) virtualization. However, this is to be
done using only bit 0 of the variable. To correct this and to prepare
for a new feature, change the current usage to work only on a particular
bit.
Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@xxxxxxx>
---
arch/x86/include/asm/svm.h | 2 ++
arch/x86/kvm/svm.c | 4 ++--
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 14824fc..d1163f6 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -119,6 +119,8 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
#define AVIC_ENABLE_SHIFT 31
#define AVIC_ENABLE_MASK (1 << AVIC_ENABLE_SHIFT)
+#define LBR_CTL_ENABLE_MASK BIT_ULL(0)
+
#define SVM_INTERRUPT_SHADOW_MASK 1
#define SVM_IOIO_STR_SHIFT 2
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index ba9891a..219ac81 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -945,7 +945,7 @@ static void svm_enable_lbrv(struct vcpu_svm *svm)
{
u32 *msrpm = svm->msrpm;
- svm->vmcb->control.lbr_ctl = 1;
+ svm->vmcb->control.lbr_ctl |= LBR_CTL_ENABLE_MASK;
set_msr_interception(msrpm, MSR_IA32_LASTBRANCHFROMIP, 1, 1);
set_msr_interception(msrpm, MSR_IA32_LASTBRANCHTOIP, 1, 1);
set_msr_interception(msrpm, MSR_IA32_LASTINTFROMIP, 1, 1);
@@ -956,7 +956,7 @@ static void svm_disable_lbrv(struct vcpu_svm *svm)
{
u32 *msrpm = svm->msrpm;
- svm->vmcb->control.lbr_ctl = 0;
+ svm->vmcb->control.lbr_ctl &= ~LBR_CTL_ENABLE_MASK;
set_msr_interception(msrpm, MSR_IA32_LASTBRANCHFROMIP, 0, 0);
set_msr_interception(msrpm, MSR_IA32_LASTBRANCHTOIP, 0, 0);
set_msr_interception(msrpm, MSR_IA32_LASTINTFROMIP, 0, 0);
--
2.7.4
