From 1221f1504140b2c4aa56b66ee52c714506a04eed Mon Sep 17 00:00:00 2001 From: Roman Kagan Date: Fri, 30 Mar 2018 20:02:09 +0300 Subject: [PATCH] i386/hyperv: error out if features requested but unsupported In order to guarantee compatibility on migration, QEMU should have complete control over the features it announces to the guest via CPUID. However, for a number of Hyper-V-related cpu properties, if the corresponding feature is not supported by the underlying KVM, the propery is silently ignored and the feature is not announced to the guest. Refuse to start with an error instead. Signed-off-by: Roman Kagan Message-Id: <20180330170209.20627-3-rkagan@virtuozzo.com> Reviewed-by: Eduardo Habkost Signed-off-by: Paolo Bonzini --- target/i386/kvm.c | 43 ++++++++++++++++++++++++++++++++++--------- 1 file changed, 34 insertions(+), 9 deletions(-) diff --git a/target/i386/kvm.c b/target/i386/kvm.c index b35623ae24..6c49954e68 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -632,11 +632,6 @@ static int hyperv_handle_properties(CPUState *cs) X86CPU *cpu = X86_CPU(cs); CPUX86State *env = &cpu->env; - if (cpu->hyperv_time && - kvm_check_extension(cs->kvm_state, KVM_CAP_HYPERV_TIME) <= 0) { - cpu->hyperv_time = false; - } - if (cpu->hyperv_relaxed_timing) { env->features[FEAT_HYPERV_EAX] |= HV_HYPERCALL_AVAILABLE; } @@ -645,6 +640,12 @@ static int hyperv_handle_properties(CPUState *cs) env->features[FEAT_HYPERV_EAX] |= HV_APIC_ACCESS_AVAILABLE; } if (cpu->hyperv_time) { + if (kvm_check_extension(cs->kvm_state, KVM_CAP_HYPERV_TIME) <= 0) { + fprintf(stderr, "Hyper-V clocksources " + "(requested by 'hv-time' cpu flag) " + "are not supported by kernel\n"); + return -ENOSYS; + } env->features[FEAT_HYPERV_EAX] |= HV_HYPERCALL_AVAILABLE; env->features[FEAT_HYPERV_EAX] |= HV_TIME_REF_COUNT_AVAILABLE; env->features[FEAT_HYPERV_EAX] |= HV_REFERENCE_TSC_AVAILABLE; @@ -659,17 +660,41 @@ static int hyperv_handle_properties(CPUState *cs) env->features[FEAT_HYPERV_EAX] |= HV_ACCESS_FREQUENCY_MSRS; env->features[FEAT_HYPERV_EDX] |= HV_FREQUENCY_MSRS_AVAILABLE; } - if (cpu->hyperv_crash && has_msr_hv_crash) { + if (cpu->hyperv_crash) { + if (!has_msr_hv_crash) { + fprintf(stderr, "Hyper-V crash MSRs " + "(requested by 'hv-crash' cpu flag) " + "are not supported by kernel\n"); + return -ENOSYS; + } env->features[FEAT_HYPERV_EDX] |= HV_GUEST_CRASH_MSR_AVAILABLE; } env->features[FEAT_HYPERV_EDX] |= HV_CPU_DYNAMIC_PARTITIONING_AVAILABLE; - if (cpu->hyperv_reset && has_msr_hv_reset) { + if (cpu->hyperv_reset) { + if (!has_msr_hv_reset) { + fprintf(stderr, "Hyper-V reset MSR " + "(requested by 'hv-reset' cpu flag) " + "is not supported by kernel\n"); + return -ENOSYS; + } env->features[FEAT_HYPERV_EAX] |= HV_RESET_AVAILABLE; } - if (cpu->hyperv_vpindex && has_msr_hv_vpindex) { + if (cpu->hyperv_vpindex) { + if (!has_msr_hv_vpindex) { + fprintf(stderr, "Hyper-V VP_INDEX MSR " + "(requested by 'hv-vpindex' cpu flag) " + "is not supported by kernel\n"); + return -ENOSYS; + } env->features[FEAT_HYPERV_EAX] |= HV_VP_INDEX_AVAILABLE; } - if (cpu->hyperv_runtime && has_msr_hv_runtime) { + if (cpu->hyperv_runtime) { + if (!has_msr_hv_runtime) { + fprintf(stderr, "Hyper-V VP_RUNTIME MSR " + "(requested by 'hv-runtime' cpu flag) " + "is not supported by kernel\n"); + return -ENOSYS; + } env->features[FEAT_HYPERV_EAX] |= HV_VP_RUNTIME_AVAILABLE; } if (cpu->hyperv_synic) {