diff options
| -rw-r--r-- | arch/x86/kvm/x86.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6b667c651951..cf33b7d910a6 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1559,6 +1559,25 @@ static u32 msr_based_features[ARRAY_SIZE(msr_based_features_all_except_vmx) + static unsigned int num_msr_based_features; /* + * All feature MSRs except uCode revID, which tracks the currently loaded uCode + * patch, are immutable once the vCPU model is defined. + */ +static bool kvm_is_immutable_feature_msr(u32 msr) +{ + int i; + + if (msr >= KVM_FIRST_EMULATED_VMX_MSR && msr <= KVM_LAST_EMULATED_VMX_MSR) + return true; + + for (i = 0; i < ARRAY_SIZE(msr_based_features_all_except_vmx); i++) { + if (msr == msr_based_features_all_except_vmx[i]) + return msr != MSR_IA32_UCODE_REV; + } + + return false; +} + +/* * Some IA32_ARCH_CAPABILITIES bits have dependencies on MSRs that KVM * does not yet virtualize. These include: * 10 - MISC_PACKAGE_CTRLS @@ -2175,6 +2194,22 @@ static int do_get_msr(struct kvm_vcpu *vcpu, unsigned index, u64 *data) static int do_set_msr(struct kvm_vcpu *vcpu, unsigned index, u64 *data) { + u64 val; + + /* + * Disallow writes to immutable feature MSRs after KVM_RUN. KVM does + * not support modifying the guest vCPU model on the fly, e.g. changing + * the nVMX capabilities while L2 is running is nonsensical. Ignore + * writes of the same value, e.g. to allow userspace to blindly stuff + * all MSRs when emulating RESET. + */ + if (kvm_vcpu_has_run(vcpu) && kvm_is_immutable_feature_msr(index)) { + if (do_get_msr(vcpu, index, &val) || *data != val) + return -EINVAL; + + return 0; + } + return kvm_set_msr_ignored_check(vcpu, index, *data, true); } |