diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 1da558f28aa5..b9d14fdbd2d8 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -4327,7 +4327,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) !guest_has_spec_ctrl_msr(vcpu)) return 1; - if (data & ~kvm_spec_ctrl_valid_bits(vcpu)) + if (kvm_spec_ctrl_test_value(data)) return 1; svm->spec_ctrl = data; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index e7fd2f00edc1..e177848a3631 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1974,7 +1974,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) !guest_has_spec_ctrl_msr(vcpu)) return 1; - if (data & ~kvm_spec_ctrl_valid_bits(vcpu)) + if (kvm_spec_ctrl_test_value(data)) return 1; vmx->spec_ctrl = data; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 73095d721399..153659e8f403 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10374,28 +10374,32 @@ bool kvm_arch_no_poll(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(kvm_arch_no_poll); -u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu) + +int kvm_spec_ctrl_test_value(u64 value) { - uint64_t bits = SPEC_CTRL_IBRS | SPEC_CTRL_STIBP | SPEC_CTRL_SSBD; + /* + * test that setting IA32_SPEC_CTRL to given value + * is allowed by the host processor + */ - /* The STIBP bit doesn't fault even if it's not advertised */ - if (!guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) && - !guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS)) - bits &= ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP); - if (!boot_cpu_has(X86_FEATURE_SPEC_CTRL) && - !boot_cpu_has(X86_FEATURE_AMD_IBRS)) - bits &= ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP); + u64 saved_value; + unsigned long flags; + int ret = 0; - if (!guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL_SSBD) && - !guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD)) - bits &= ~SPEC_CTRL_SSBD; - if (!boot_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) && - !boot_cpu_has(X86_FEATURE_AMD_SSBD)) - bits &= ~SPEC_CTRL_SSBD; + local_irq_save(flags); - return bits; + if (rdmsrl_safe(MSR_IA32_SPEC_CTRL, &saved_value)) + ret = 1; + else if (wrmsrl_safe(MSR_IA32_SPEC_CTRL, value)) + ret = 1; + else + wrmsrl(MSR_IA32_SPEC_CTRL, saved_value); + + local_irq_restore(flags); + + return ret; } -EXPORT_SYMBOL_GPL(kvm_spec_ctrl_valid_bits); +EXPORT_SYMBOL_GPL(kvm_spec_ctrl_test_value); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio); diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 301286d92432..c520d373790a 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -368,6 +368,6 @@ static inline bool kvm_pat_valid(u64 data) void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu); void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu); -u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu); +int kvm_spec_ctrl_test_value(u64 value); #endif