Linux Patch #10
PATCH v6 10/10 Linux Patch #10
Expose the CPUID.7.EDX[31] bit to the guest, and also guard against various combinations of of SPEC_CTRL MSR values.
The handling of MSR (to take into account the host value of SPEC_CTRL Bit(2)) is taken care of in patch:
KVM/SVM/VMX/x86/spectre_v2: Support the combination of guest IBRS and ours.
Signed-off-by Konrad Rzeszutek Wilk <[email protected]>
---
v2: New patch.
v4: s/MDD/RDS/
--- arch/x86/kvm/cpuid.c | 2 +- arch/x86/kvm/vmx.c | 8 +++++--- 2 files changed, 6 insertions(+), 4 deletions(-)
arch/x86/kvm/cpuid.c +1 -1
@@ -407,7 +407,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,/* cpuid 7.0.edx*/ const u32 kvm_cpuid_7_0_edx_x86_features = -F (AVX512_4VNNIW ) |F (AVX512_4FMAPS ) |F (SPEC_CTRL ) | +F (AVX512_4VNNIW ) |F (AVX512_4FMAPS ) |F (SPEC_CTRL ) |F (RDS ) |F (ARCH_CAPABILITIES );/* all calls to cpuid_count() should be made on the same cpu */
arch/x86/kvm/vmx.c +5 -3
@@ -3524,7 +3524,8 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)case MSR_IA32_SPEC_CTRL :if (!msr_info->host_initiated && !guest_cpuid_has (vcpu,X86_FEATURE_IBRS ) && - !guest_cpuid_has (vcpu,X86_FEATURE_SPEC_CTRL )) + !guest_cpuid_has (vcpu,X86_FEATURE_SPEC_CTRL ) && + !guest_cpuid_has (vcpu,X86_FEATURE_RDS ))return 1 ; msr_info->data =to_vmx (vcpu)->spec_ctrl;
@@ -3643,11 +3644,12 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)case MSR_IA32_SPEC_CTRL :if (!msr_info->host_initiated && !guest_cpuid_has (vcpu,X86_FEATURE_IBRS ) && - !guest_cpuid_has (vcpu,X86_FEATURE_SPEC_CTRL )) + !guest_cpuid_has (vcpu,X86_FEATURE_SPEC_CTRL ) && + !guest_cpuid_has (vcpu,X86_FEATURE_RDS ))return 1 ;/* The STIBP bit doesn't fault even if it's not advertised */ -if (data & ~(SPEC_CTRL_IBRS |SPEC_CTRL_STIBP )) +if (data & ~(SPEC_CTRL_IBRS |SPEC_CTRL_STIBP |SPEC_CTRL_RDS ))return 1 ; vmx->spec_ctrl = data;
Signature · 1 line
2.14.3