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bh=skdk48aJyf/65+fkWAFyVF904IQGtwuPwwRzyOq7gN4=; b=Eg9f3nk36x3j1ogzmJqiBaOqSiMD9EddcYQHeQF/i9pNPYSSf1MFfbuGlVodgo1nsbfU2M x5Hc/H76D8IieDRgIVUSU5xOtgu7+UvenFnPjs8nstHXRqtMXXzm4mqgKqwtn0DogbbRJR tZnncIf7qIwaVSNOLzOpV0KYj7g+nlg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-415-be7mlAHeOjOx57ovyiwV5A-1; Fri, 21 May 2021 17:20:23 -0400 X-MC-Unique: be7mlAHeOjOx57ovyiwV5A-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8B4F4801B13 for ; Fri, 21 May 2021 21:20:22 +0000 (UTC) Received: from localhost (ovpn-115-27.rdu2.redhat.com [10.10.115.27]) by smtp.corp.redhat.com (Postfix) with ESMTP id 525E460CCC; Fri, 21 May 2021 21:20:22 +0000 (UTC) Date: Fri, 21 May 2021 17:20:21 -0400 From: Eduardo Habkost To: Vitaly Kuznetsov Subject: Re: [PATCH v6 10/19] i386: move eVMCS enablement to hyperv_init_vcpu() Message-ID: <20210521212021.lsf2pzfu647ocqj3@habkost.net> References: <20210422161130.652779-1-vkuznets@redhat.com> <20210422161130.652779-11-vkuznets@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210422161130.652779-11-vkuznets@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=ehabkost@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=ehabkost@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.374, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini , Marcelo Tosatti , qemu-devel@nongnu.org, Igor Mammedov Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Apr 22, 2021 at 06:11:21PM +0200, Vitaly Kuznetsov wrote: > hyperv_expand_features() will be called before we create vCPU so > evmcs enablement should go away. hyperv_init_vcpu() looks like the > right place. > > Signed-off-by: Vitaly Kuznetsov > --- > target/i386/kvm/kvm.c | 60 ++++++++++++++++++++++++++----------------- > 1 file changed, 37 insertions(+), 23 deletions(-) > > diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c > index 6b391db7a030..a2ef2dc154a2 100644 > --- a/target/i386/kvm/kvm.c > +++ b/target/i386/kvm/kvm.c > @@ -962,6 +962,7 @@ static struct kvm_cpuid2 *get_supported_hv_cpuid(CPUState *cs) > { > struct kvm_cpuid2 *cpuid; > int max = 7; /* 0x40000000..0x40000005, 0x4000000A */ > + int i; > > /* > * When the buffer is too small, KVM_GET_SUPPORTED_HV_CPUID fails with > @@ -971,6 +972,22 @@ static struct kvm_cpuid2 *get_supported_hv_cpuid(CPUState *cs) > while ((cpuid = try_get_hv_cpuid(cs, max)) == NULL) { > max++; > } > + > + /* > + * KVM_GET_SUPPORTED_HV_CPUID does not set EVMCS CPUID bit before > + * KVM_CAP_HYPERV_ENLIGHTENED_VMCS is enabled but we want to get the > + * information early, just check for the capability and set the bit > + * manually. > + */ Should we add a comment noting that this hack won't be necessary if using the system ioctl? I assume we still want to support Linux < v5.11 for a while, so simply > + if (kvm_check_extension(cs->kvm_state, > + KVM_CAP_HYPERV_ENLIGHTENED_VMCS) > 0) { > + for (i = 0; i < cpuid->nent; i++) { > + if (cpuid->entries[i].function == HV_CPUID_ENLIGHTMENT_INFO) { > + cpuid->entries[i].eax |= HV_ENLIGHTENED_VMCS_RECOMMENDED; > + } > + } > + } > + > return cpuid; > } > > @@ -1200,24 +1217,6 @@ static int hyperv_expand_features(CPUState *cs) > if (!hyperv_enabled(cpu)) > return 0; > > - if (hyperv_feat_enabled(cpu, HYPERV_FEAT_EVMCS) || > - cpu->hyperv_passthrough) { > - uint16_t evmcs_version; > - > - r = kvm_vcpu_enable_cap(cs, KVM_CAP_HYPERV_ENLIGHTENED_VMCS, 0, > - (uintptr_t)&evmcs_version); > - > - if (hyperv_feat_enabled(cpu, HYPERV_FEAT_EVMCS) && r) { > - fprintf(stderr, "Hyper-V %s is not supported by kernel\n", > - kvm_hyperv_properties[HYPERV_FEAT_EVMCS].desc); > - return -ENOSYS; > - } > - > - if (!r) { > - cpu->hyperv_nested[0] = evmcs_version; > - } > - } > - > if (cpu->hyperv_passthrough) { > cpu->hyperv_vendor_id[0] = > hv_cpuid_get_host(cs, HV_CPUID_VENDOR_AND_MAX_FUNCTIONS, R_EBX); > @@ -1455,6 +1454,21 @@ static int hyperv_init_vcpu(X86CPU *cpu) > } > } > > + if (hyperv_feat_enabled(cpu, HYPERV_FEAT_EVMCS)) { > + uint16_t evmcs_version; > + > + ret = kvm_vcpu_enable_cap(cs, KVM_CAP_HYPERV_ENLIGHTENED_VMCS, 0, > + (uintptr_t)&evmcs_version); > + > + if (ret < 0) { > + fprintf(stderr, "Hyper-V %s is not supported by kernel\n", > + kvm_hyperv_properties[HYPERV_FEAT_EVMCS].desc); > + return ret; > + } > + > + cpu->hyperv_nested[0] = evmcs_version; Wait, won't this break guest ABI? Do we want to make HYPERV_FEAT_EVMCS a migration blocker until this is fixed? > + } > + > return 0; > } > > @@ -1519,6 +1533,11 @@ int kvm_arch_init_vcpu(CPUState *cs) > } > > if (hyperv_enabled(cpu)) { > + r = hyperv_init_vcpu(cpu); > + if (r) { > + return r; > + } > + > cpuid_i = hyperv_fill_cpuids(cs, cpuid_data.entries); > kvm_base = KVM_CPUID_SIGNATURE_NEXT; > has_msr_hv_hypercall = true; > @@ -1868,11 +1887,6 @@ int kvm_arch_init_vcpu(CPUState *cs) > > kvm_init_msrs(cpu); > > - r = hyperv_init_vcpu(cpu); > - if (r) { > - goto fail; > - } > - > return 0; I would move the two hunks above to a separate patch, but not a big deal. The guest ABI issue is existing, and the comment suggestion can be done in a follow up patch, so: Reviewed-by: Eduardo Habkost > > fail: > -- > 2.30.2 > -- Eduardo