[tip:x86/pti] KVM/x86: Remove indirect MSR op calls from SPEC_CTRL

[tip-bot for Paolo Bonzini]

Commit-ID:  ecb586bd29c99fb4de599dec388658e74388daad
Gitweb: https://git.kernel.org/tip/ecb586bd29c99fb4de599dec388658e74388daad
Author: Paolo Bonzini 
AuthorDate: Thu, 22 Feb 2018 16:43:17 +0100
Committer:  Ingo Molnar 
CommitDate: Fri, 23 Feb 2018 08:24:35 +0100

KVM/x86: Remove indirect MSR op calls from SPEC_CTRL

Having a paravirt indirect call in the IBRS restore path is not a
good idea, since we are trying to protect from speculative execution
of bogus indirect branch targets.  It is also slower, so use
native_wrmsrl() on the vmentry path too.

Signed-off-by: Paolo Bonzini 
Reviewed-by: Jim Mattson 
Cc: David Woodhouse 
Cc: KarimAllah Ahmed 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Radim Krčmář 
Cc: Thomas Gleixner 
Cc: k...@vger.kernel.org
Cc: sta...@vger.kernel.org
Fixes: d28b387fb74da95d69d2615732f50cceb38e9a4d
Link: http://lkml.kernel.org/r/20180222154318.20361-2-pbonz...@redhat.com
Signed-off-by: Ingo Molnar 
---
 arch/x86/kvm/svm.c | 7 ---
 arch/x86/kvm/vmx.c | 7 ---
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b3e488a74828..1598beeda11c 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -49,6 +49,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 
 #include 
@@ -5355,7 +5356,7 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
 * being speculatively taken.
 */
if (svm->spec_ctrl)
-   wrmsrl(MSR_IA32_SPEC_CTRL, svm->spec_ctrl);
+   native_wrmsrl(MSR_IA32_SPEC_CTRL, svm->spec_ctrl);
 
asm volatile (
"push %%" _ASM_BP "; \n\t"
@@ -5465,10 +5466,10 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
 * save it.
 */
if (!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL))
-   rdmsrl(MSR_IA32_SPEC_CTRL, svm->spec_ctrl);
+   svm->spec_ctrl = native_read_msr(MSR_IA32_SPEC_CTRL);
 
if (svm->spec_ctrl)
-   wrmsrl(MSR_IA32_SPEC_CTRL, 0);
+   native_wrmsrl(MSR_IA32_SPEC_CTRL, 0);
 
/* Eliminate branch target predictions from guest mode */
vmexit_fill_RSB();
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 3dec126aa302..0927be315965 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -51,6 +51,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 
 #include "trace.h"
@@ -9452,7 +9453,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
 * being speculatively taken.
 */
if (vmx->spec_ctrl)
-   wrmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
+   native_wrmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
 
vmx->__launched = vmx->loaded_vmcs->launched;
asm(
@@ -9588,10 +9589,10 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu 
*vcpu)
 * save it.
 */
if (!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL))
-   rdmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
+   vmx->spec_ctrl = native_read_msr(MSR_IA32_SPEC_CTRL);
 
if (vmx->spec_ctrl)
-   wrmsrl(MSR_IA32_SPEC_CTRL, 0);
+   native_wrmsrl(MSR_IA32_SPEC_CTRL, 0);
 
/* Eliminate branch target predictions from guest mode */
vmexit_fill_RSB();

[tip:x86/pti] KVM/x86: Remove indirect MSR op calls from SPEC_CTRL

[tip-bot for Paolo Bonzini]

Commit-ID:  ecb586bd29c99fb4de599dec388658e74388daad
Gitweb: https://git.kernel.org/tip/ecb586bd29c99fb4de599dec388658e74388daad
Author: Paolo Bonzini 
AuthorDate: Thu, 22 Feb 2018 16:43:17 +0100
Committer:  Ingo Molnar 
CommitDate: Fri, 23 Feb 2018 08:24:35 +0100

KVM/x86: Remove indirect MSR op calls from SPEC_CTRL

Having a paravirt indirect call in the IBRS restore path is not a
good idea, since we are trying to protect from speculative execution
of bogus indirect branch targets.  It is also slower, so use
native_wrmsrl() on the vmentry path too.

Signed-off-by: Paolo Bonzini 
Reviewed-by: Jim Mattson 
Cc: David Woodhouse 
Cc: KarimAllah Ahmed 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Radim Krčmář 
Cc: Thomas Gleixner 
Cc: k...@vger.kernel.org
Cc: sta...@vger.kernel.org
Fixes: d28b387fb74da95d69d2615732f50cceb38e9a4d
Link: http://lkml.kernel.org/r/20180222154318.20361-2-pbonz...@redhat.com
Signed-off-by: Ingo Molnar 
---
 arch/x86/kvm/svm.c | 7 ---
 arch/x86/kvm/vmx.c | 7 ---
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b3e488a74828..1598beeda11c 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -49,6 +49,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 
 #include 
@@ -5355,7 +5356,7 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
 * being speculatively taken.
 */
if (svm->spec_ctrl)
-   wrmsrl(MSR_IA32_SPEC_CTRL, svm->spec_ctrl);
+   native_wrmsrl(MSR_IA32_SPEC_CTRL, svm->spec_ctrl);
 
asm volatile (
"push %%" _ASM_BP "; \n\t"
@@ -5465,10 +5466,10 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
 * save it.
 */
if (!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL))
-   rdmsrl(MSR_IA32_SPEC_CTRL, svm->spec_ctrl);
+   svm->spec_ctrl = native_read_msr(MSR_IA32_SPEC_CTRL);
 
if (svm->spec_ctrl)
-   wrmsrl(MSR_IA32_SPEC_CTRL, 0);
+   native_wrmsrl(MSR_IA32_SPEC_CTRL, 0);
 
/* Eliminate branch target predictions from guest mode */
vmexit_fill_RSB();
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 3dec126aa302..0927be315965 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -51,6 +51,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 
 #include "trace.h"
@@ -9452,7 +9453,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
 * being speculatively taken.
 */
if (vmx->spec_ctrl)
-   wrmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
+   native_wrmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
 
vmx->__launched = vmx->loaded_vmcs->launched;
asm(
@@ -9588,10 +9589,10 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu 
*vcpu)
 * save it.
 */
if (!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL))
-   rdmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
+   vmx->spec_ctrl = native_read_msr(MSR_IA32_SPEC_CTRL);
 
if (vmx->spec_ctrl)
-   wrmsrl(MSR_IA32_SPEC_CTRL, 0);
+   native_wrmsrl(MSR_IA32_SPEC_CTRL, 0);
 
/* Eliminate branch target predictions from guest mode */
vmexit_fill_RSB();