Hello Paolo,
I've back ported this patch on 4.1, after adding the per-vcpu MSR
bitmap. Also enabled the SPEC_CTRL_MSR intercept if qemu instructed so [1].
Reviewed-by: Mihai Carabas <mihai.carabas@xxxxxxxxxx>
[1]
+++ b/arch/x86/kvm/vmx.c
@@ -8391,6 +8391,16 @@ static struct kvm_vcpu *vmx_create_vcpu(struct
kvm *kvm, unsigned int id)
vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_PRED_CMD,
MSR_TYPE_R | MSR_TYPE_W);
vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_BNDCFGS,
MSR_TYPE_R | MSR_TYPE_W);
+ /*
+ * If the physical CPU or the vCPU of this VM doesn't
+ * support SPEC_CTRL feature, catch each access to it.
+ */
+ if (!static_cpu_has(X86_FEATURE_SPEC_CTRL) ||
+ !guest_cpuid_has_spec_ctrl(&vmx->vcpu))
+ vmx_enable_intercept_for_msr(
+ msr_bitmap,
+ MSR_IA32_SPEC_CTRL,
+ MSR_TYPE_R | MSR_TYPE_W);
/*
* If PML is turned on, failure on enabling PML just results in
failure
On 09.01.2018 14:03, Paolo Bonzini wrote:
MSR_IA32_SPEC_CTRL is not available unless CPU[7,0].EDX[26] is 1.
Check that against host CPUID or guest CPUID, respectively for
host-initiated and guest-initiated accesses.
Suggested-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
This is for after X86_FEATURE_SPEC_CTRL is added to Linux, but
I still wanted to ack Jim's improvement.
arch/x86/kvm/svm.c | 8 ++++++++
arch/x86/kvm/vmx.c | 8 ++++++++
2 files changed, 16 insertions(+)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 97126c2bd663..3a646580d7c5 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3648,6 +3648,10 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
msr_info->data = svm->nested.vm_cr_msr;
break;
case MSR_IA32_SPEC_CTRL:
+ if (!static_cpu_has(X86_FEATURE_SPEC_CTRL) ||
+ (!msr_info->host_initiated &&
+ !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL)))
+ return 1;
msr_info->data = svm->spec_ctrl;
break;
case MSR_IA32_UCODE_REV:
@@ -3806,6 +3810,10 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
vcpu_unimpl(vcpu, "unimplemented wrmsr: 0x%x data 0x%llx\n", ecx, data);
break;
case MSR_IA32_SPEC_CTRL:
+ if (!static_cpu_has(X86_FEATURE_SPEC_CTRL) ||
+ (!msr_info->host_initiated &&
+ !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL)))
+ return 1;
svm->spec_ctrl = data;
break;
case MSR_IA32_APICBASE:
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 49b4a2d61603..42bc7ee293e4 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3368,6 +3368,10 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
msr_info->data = guest_read_tsc(vcpu);
break;
case MSR_IA32_SPEC_CTRL:
+ if (!static_cpu_has(X86_FEATURE_SPEC_CTRL) ||
+ (!msr_info->host_initiated &&
+ !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL)))
+ return 1;
msr_info->data = to_vmx(vcpu)->spec_ctrl;
break;
case MSR_IA32_SYSENTER_CS:
@@ -3510,6 +3514,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
kvm_write_tsc(vcpu, msr_info);
break;
case MSR_IA32_SPEC_CTRL:
+ if (!static_cpu_has(X86_FEATURE_SPEC_CTRL) ||
+ (!msr_info->host_initiated &&
+ !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL)))
+ return 1;
to_vmx(vcpu)->spec_ctrl = data;
break;
case MSR_IA32_CR_PAT:
