From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55474) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f1D2B-0001ZM-6j for qemu-devel@nongnu.org; Wed, 28 Mar 2018 11:30:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f1D27-0005xG-7Y for qemu-devel@nongnu.org; Wed, 28 Mar 2018 11:30:43 -0400 Received: from mail-db5eur01on0115.outbound.protection.outlook.com ([104.47.2.115]:29664 helo=EUR01-DB5-obe.outbound.protection.outlook.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1f1D26-0005tY-VW for qemu-devel@nongnu.org; Wed, 28 Mar 2018 11:30:39 -0400 From: Roman Kagan Date: Wed, 28 Mar 2018 18:30:24 +0300 Message-Id: <20180328153024.23039-3-rkagan@virtuozzo.com> In-Reply-To: <20180328153024.23039-1-rkagan@virtuozzo.com> References: <20180328153024.23039-1-rkagan@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain Subject: [Qemu-devel] [PATCH for-2.12 v2 2/2] i386/hyperv: error out if features requested but unsupported List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, Paolo Bonzini , Eduardo Habkost , Vitaly Kuznetsov 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 --- v1 -> v2: - indicate what flag requested the feature that can't be enabled in the error message - fix a typo in the error message for VP_RUNTIME target/i386/kvm.c | 32 ++++++++++++++++++++++++++++---- 1 file changed, 28 insertions(+), 4 deletions(-) diff --git a/target/i386/kvm.c b/target/i386/kvm.c index b35623ae24..113926aff2 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -659,17 +659,41 @@ 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) { -- 2.14.3