From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: jmattson@google.com, aliguori@amazon.com,
thomas.lendacky@amd.com, dwmw@amazon.co.uk, bp@alien8.de
Subject: [PATCH 3/7] kvm: vmx: pass MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD down to the guest
Date: Mon, 8 Jan 2018 19:08:41 +0100 [thread overview]
Message-ID: <1515434925-10250-4-git-send-email-pbonzini@redhat.com> (raw)
In-Reply-To: <1515434925-10250-1-git-send-email-pbonzini@redhat.com>
Direct access to MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD is important
for performance. Allow load/store of MSR_IA32_SPEC_CTRL, restore guest
IBRS on VM entry and set it to 0 on VM exit (because Linux does not use
it yet).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 669f5f74857d..d00bcad7336e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -120,6 +120,8 @@
module_param_named(preemption_timer, enable_preemption_timer, bool, S_IRUGO);
#endif
+static bool __read_mostly have_spec_ctrl;
+
#define KVM_GUEST_CR0_MASK (X86_CR0_NW | X86_CR0_CD)
#define KVM_VM_CR0_ALWAYS_ON_UNRESTRICTED_GUEST (X86_CR0_WP | X86_CR0_NE)
#define KVM_VM_CR0_ALWAYS_ON \
@@ -609,6 +611,8 @@ struct vcpu_vmx {
u64 msr_host_kernel_gs_base;
u64 msr_guest_kernel_gs_base;
#endif
+ u64 spec_ctrl;
+
u32 vm_entry_controls_shadow;
u32 vm_exit_controls_shadow;
u32 secondary_exec_control;
@@ -3361,6 +3365,9 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_IA32_TSC:
msr_info->data = guest_read_tsc(vcpu);
break;
+ case MSR_IA32_SPEC_CTRL:
+ msr_info->data = to_vmx(vcpu)->spec_ctrl;
+ break;
case MSR_IA32_SYSENTER_CS:
msr_info->data = vmcs_read32(GUEST_SYSENTER_CS);
break;
@@ -3500,6 +3507,9 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_IA32_TSC:
kvm_write_tsc(vcpu, msr_info);
break;
+ case MSR_IA32_SPEC_CTRL:
+ to_vmx(vcpu)->spec_ctrl = msr_info->data;
+ break;
case MSR_IA32_CR_PAT:
if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data))
@@ -7062,6 +7072,17 @@ static __init int hardware_setup(void)
goto out;
}
+ /*
+ * FIXME: this is only needed until SPEC_CTRL is supported
+ * by upstream Linux in cpufeatures, then it can be replaced
+ * with static_cpu_has.
+ */
+ have_spec_ctrl = cpu_has_spec_ctrl();
+ if (have_spec_ctrl)
+ pr_info("kvm: SPEC_CTRL available\n");
+ else
+ pr_info("kvm: SPEC_CTRL not available\n");
+
if (boot_cpu_has(X86_FEATURE_NX))
kvm_enable_efer_bits(EFER_NX);
@@ -7131,6 +7152,8 @@ static __init int hardware_setup(void)
vmx_disable_intercept_for_msr(MSR_IA32_SYSENTER_CS, false);
vmx_disable_intercept_for_msr(MSR_IA32_SYSENTER_ESP, false);
vmx_disable_intercept_for_msr(MSR_IA32_SYSENTER_EIP, false);
+ vmx_disable_intercept_for_msr(MSR_IA32_SPEC_CTRL, false);
+ vmx_disable_intercept_for_msr(MSR_IA32_PRED_CMD, false);
memcpy(vmx_msr_bitmap_legacy_x2apic_apicv,
vmx_msr_bitmap_legacy, PAGE_SIZE);
@@ -9597,6 +9620,9 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
pt_guest_enter(vmx);
+ if (have_spec_ctrl && vmx->spec_ctrl != 0)
+ wrmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
+
atomic_switch_perf_msrs(vmx);
vmx_arm_hv_timer(vcpu);
@@ -9707,6 +9733,12 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
#endif
);
+ if (have_spec_ctrl) {
+ rdmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
+ if (vmx->spec_ctrl)
+ wrmsrl(MSR_IA32_SPEC_CTRL, 0);
+ }
+
/* MSR_IA32_DEBUGCTLMSR is zeroed on vmexit. Restore it if needed */
if (vmx->host_debugctlmsr)
update_debugctlmsr(vmx->host_debugctlmsr);
--
1.8.3.1
next prev parent reply other threads:[~2018-01-08 18:09 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-08 18:08 [PATCH 0/7] KVM: x86: expose CVE-2017-5715 ("Spectre variant 2") mitigations to guest Paolo Bonzini
2018-01-08 18:08 ` [PATCH 1/7] KVM: x86: add SPEC_CTRL and IBPB_SUPPORT accessors Paolo Bonzini
2018-01-08 18:33 ` Konrad Rzeszutek Wilk
2018-01-08 19:09 ` Liran Alon
2018-01-09 10:32 ` Paolo Bonzini
2018-01-09 11:14 ` David Hildenbrand
2018-01-09 11:18 ` Paolo Bonzini
2018-01-08 18:08 ` [PATCH 2/7] x86/msr: add definitions for indirect branch predictor MSRs Paolo Bonzini
2018-01-08 18:35 ` Konrad Rzeszutek Wilk
2018-01-08 18:52 ` Jim Mattson
2018-01-08 19:10 ` Liran Alon
2018-01-08 18:08 ` Paolo Bonzini [this message]
2018-01-08 18:43 ` [PATCH 3/7] kvm: vmx: pass MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD down to the guest Konrad Rzeszutek Wilk
2018-01-08 19:18 ` Jim Mattson
2018-01-08 20:23 ` Liran Alon
2018-01-08 22:32 ` Paolo Bonzini
2018-01-08 23:19 ` Jim Mattson
2018-01-09 10:11 ` Paolo Bonzini
2018-01-08 19:22 ` Liran Alon
2018-01-08 19:41 ` David Woodhouse
2018-01-08 22:33 ` Paolo Bonzini
2018-01-08 22:09 ` Ashok Raj
2018-01-08 22:25 ` Paolo Bonzini
2018-01-11 2:47 ` Tim Chen
2018-01-11 10:41 ` Paolo Bonzini
2018-01-08 18:08 ` [PATCH 4/7] kvm: vmx: Set IBPB when running a different VCPU Paolo Bonzini
2018-01-08 19:23 ` Liran Alon
2018-01-08 19:36 ` Jim Mattson
2018-01-09 8:33 ` Paolo Bonzini
2018-01-09 11:01 ` David Hildenbrand
2018-01-08 18:08 ` [PATCH 5/7] kvm: svm: pass MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD down to guest Paolo Bonzini
2018-01-08 19:41 ` Liran Alon
2018-01-08 18:08 ` [PATCH 6/7] x86/svm: Set IBPB when running a different VCPU Paolo Bonzini
2018-01-08 20:00 ` Liran Alon
2018-01-09 11:07 ` Paolo Bonzini
2018-01-08 18:08 ` [PATCH 7/7] KVM: x86: add SPEC_CTRL and IBPB_SUPPORT to MSR and CPUID lists Paolo Bonzini
2018-01-08 20:07 ` Liran Alon
2018-01-08 20:15 ` Jim Mattson
2018-01-09 10:15 ` [PATCH 0/7] KVM: x86: expose CVE-2017-5715 ("Spectre variant 2") mitigations to guest Thomas Gleixner
2018-01-09 11:12 ` Paolo Bonzini
2018-01-09 12:03 ` Thomas Gleixner
2018-01-09 14:06 ` Paolo Bonzini
2018-01-08 23:58 [PATCH 3/7] kvm: vmx: pass MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD down to the guest Liran Alon
2018-01-09 8:35 ` Paolo Bonzini
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