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From: Youquan Song <youquan.song@intel.com>
To: stable@vger.kernel.org, gregkh@linuxfoundation.org
Cc: tim.c.chen@linux.intel.com, ashok.raj@intel.com,
	dave.hansen@intel.com, yi.y.sun@linux.intel.com,
	youquan.song@intel.com, youquan.song@linux.intel.com,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"David Woodhouse" <dwmw@amazon.co.uk>,
	"KarimAllah Ahmed" <karahmed@amazon.de>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	kvm@vger.kernel.org
Subject: [PATCH 22/24] KVM/x86: Remove indirect MSR op calls from SPEC_CTRL
Date: Tue, 17 Apr 2018 00:27:18 -0400	[thread overview]
Message-ID: <1523939240-16508-22-git-send-email-youquan.song@intel.com> (raw)
In-Reply-To: <1523939240-16508-1-git-send-email-youquan.song@intel.com>

From: Paolo Bonzini <pbonzini@redhat.com>

commit ecb586bd29c99fb4de599dec388658e74388daad upstream.

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 <pbonzini@redhat.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: KarimAllah Ahmed <karahmed@amazon.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: d28b387fb74da95d69d2615732f50cceb38e9a4d
Link: http://lkml.kernel.org/r/20180222154318.20361-2-pbonzini@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com> [v4.4 backport]

Conflicts:
	arch/x86/kvm/svm.c
---
 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 c2bfd65..e13d7e9 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -37,6 +37,7 @@
 #include <asm/desc.h>
 #include <asm/debugreg.h>
 #include <asm/kvm_para.h>
+#include <asm/microcode.h>
 #include <asm/nospec-branch.h>
 
 #include <asm/virtext.h>
@@ -3905,7 +3906,7 @@ 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"
@@ -4015,10 +4016,10 @@ 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 cec4c32..6600952 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -48,6 +48,7 @@
 #include <asm/kexec.h>
 #include <asm/apic.h>
 #include <asm/irq_remapping.h>
+#include <asm/microcode.h>
 #include <asm/nospec-branch.h>
 
 #include "trace.h"
@@ -8617,7 +8618,7 @@ 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(
@@ -8753,10 +8754,10 @@ 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();
-- 
1.8.3.1

  parent reply	other threads:[~2018-04-16 16:58 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-17  4:26 [PATCH 01/24] x86/cpufeatures: Add CPUID_7_EDX CPUID leaf Youquan Song
2018-04-16 18:27 ` Greg KH
2018-04-17  4:26 ` [PATCH 02/24] x86/cpufeatures: Add Intel feature bits for Speculation Control Youquan Song
2018-04-17  4:26 ` [PATCH 03/24] x86/cpufeatures: Add AMD " Youquan Song
2018-04-17  4:27 ` [PATCH 04/24] x86/msr: Add definitions for new speculation control MSRs Youquan Song
2018-04-17  4:27 ` [PATCH 05/24] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown Youquan Song
2018-04-17  4:27 ` [PATCH 06/24] x86/cpufeature: Blacklist SPEC_CTRL/PRED_CMD on early Spectre v2 microcodes Youquan Song
2018-04-17  4:27 ` [PATCH 07/24] x86/speculation: Add basic IBPB (Indirect Branch Prediction Barrier) support Youquan Song
2018-04-17  4:27 ` [PATCH 08/24] x86/cpufeatures: Clean up Spectre v2 related CPUID flags Youquan Song
2018-04-17  4:27 ` [PATCH 09/24] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel Youquan Song
2018-04-17  4:27 ` [PATCH 10/24] x86/speculation: Add <asm/msr-index.h> dependency Youquan Song
2018-04-17  4:27 ` [PATCH 11/24] x86/mm: Give each mm TLB flush generation a unique ID Youquan Song
2018-04-17  4:27 ` [PATCH 12/24] x86/speculation: Use Indirect Branch Prediction Barrier in context switch Youquan Song
2018-04-17  4:27 ` [PATCH 13/24] x86/speculation: Use IBRS if available before calling into firmware Youquan Song
2018-04-17  4:27 ` [PATCH 14/24] x86/speculation: Move firmware_restrict_branch_speculation_*() from C to CPP Youquan Song
2018-04-17  4:27 ` [PATCH 15/24] KVM: nVMX: Eliminate vmcs02 pool Youquan Song
2018-04-17  4:27 ` [PATCH 16/24] KVM: VMX: introduce alloc_loaded_vmcs Youquan Song
2018-04-17  4:27 ` [PATCH 17/24] KVM: VMX: make MSR bitmaps per-VCPU Youquan Song
2018-04-17  4:27 ` [PATCH 18/24] KVM/x86: Add IBPB support Youquan Song
2018-04-17  4:27 ` [PATCH 19/24] KVM/VMX: Emulate MSR_IA32_ARCH_CAPABILITIES Youquan Song
2018-04-17  4:27 ` [PATCH 20/24] KVM/VMX: Allow direct access to MSR_IA32_SPEC_CTRL Youquan Song
2018-04-17  4:27 ` [PATCH 21/24] KVM/SVM: " Youquan Song
2018-04-17  4:27 ` Youquan Song [this message]
2018-04-17  4:27 ` [PATCH 23/24] KVM/VMX: Optimize vmx_vcpu_run() and svm_vcpu_run() by marking the RDMSR path as unlikely() Youquan Song
2018-04-17  4:27 ` [PATCH 24/24] x86/spectre_v2: Don't check microcode versions when running under hypervisors Youquan Song
2018-04-18  3:18 [PATCH 00/24] Backport Speculation Control support for 4.4 Youquan Song
2018-04-18  3:18 ` [PATCH 22/24] KVM/x86: Remove indirect MSR op calls from SPEC_CTRL Youquan Song
2018-04-25 14:26   ` Greg KH

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