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bh=YaN20WxT9swZk3ctK7m51QwSlcHWzGaIIaqOlpuC7Wg=; b=inB/DsVYZx93z5tGz5SeRHcODAldTSk4qaYiuZ5itPIi6+Aw759ZRicJveegs22vbKGJH0 mrMNeWoYiTBZly6QbzXjAHmgoGB54oT+wDNZyoL0nZvdylVufXL1Cavp55uQAnnw/C67/N 0fKvybonQ7+FdtSxfBokfVyr3d5PBi8= X-MC-Unique: YeRHXkFjOPC8aG7d_krxVQ-1 From: Vitaly Kuznetsov To: qemu-devel@nongnu.org, Eduardo Habkost Subject: [PATCH 2/3] i386: Support KVM_CAP_ENFORCE_PV_FEATURE_CPUID Date: Thu, 22 Jul 2021 14:15:27 +0200 Message-Id: <20210722121528.258426-3-vkuznets@redhat.com> In-Reply-To: <20210722121528.258426-1-vkuznets@redhat.com> References: <20210722121528.258426-1-vkuznets@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=vkuznets@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=216.205.24.124; envelope-from=vkuznets@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.472, 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 , Igor Mammedov Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1626956279523100001 Content-Type: text/plain; charset="utf-8" By default, KVM allows the guest to use all currently supported PV features even when they were not announced in guest visible CPUIDs. Introduce a new "kvm-pv-enforce-cpuid" flag to limit the supported feature set to the exposed features. The feature is supported by Linux >=3D 5.10 and is not enabled by default in QEMU. Signed-off-by: Vitaly Kuznetsov --- docs/kvm-pv.txt | 13 ++++++++++++- target/i386/cpu.c | 2 ++ target/i386/cpu.h | 3 +++ target/i386/kvm/kvm.c | 10 ++++++++++ 4 files changed, 27 insertions(+), 1 deletion(-) diff --git a/docs/kvm-pv.txt b/docs/kvm-pv.txt index 84ad7fa60f8d..d1aac533feea 100644 --- a/docs/kvm-pv.txt +++ b/docs/kvm-pv.txt @@ -87,6 +87,17 @@ the number of supported vCPUs for a given configuration = lower). Tells the guest that guest visible TSC value can be fully trusted for kvmc= lock computations and no warps are expected. =20 -4. Useful links +4. Supplementary features +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D + +4.1. kvm-pv-enforce-cpuid +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D +By default, KVM allows the guest to use all currently supported PV feature= s even +when they were not announced in guest visible CPUIDs. 'kvm-pv-enforce-cpui= d' +feature alters this behavior and limits the supported feature set to the +exposed features only. + + +5. Useful links =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Please refer to Documentation/virt/kvm in Linux for additional detail. diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 48b55ebd0a67..0a0d2cddc9d2 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -6668,6 +6668,8 @@ static Property x86_cpu_properties[] =3D { DEFINE_PROP_BOOL("l3-cache", X86CPU, enable_l3_cache, true), DEFINE_PROP_BOOL("kvm-no-smi-migration", X86CPU, kvm_no_smi_migration, false), + DEFINE_PROP_BOOL("kvm-pv-enforce-cpuid", X86CPU, kvm_pv_enforce_cpuid, + false), DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, vmware_cpuid_freq, true), DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true), DEFINE_PROP_BOOL("x-migrate-smi-count", X86CPU, migrate_smi_count, diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 5d98a4e7c025..31f1f7caf116 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -1768,6 +1768,9 @@ struct X86CPU { /* Stop SMI delivery for migration compatibility with old machines */ bool kvm_no_smi_migration; =20 + /* Forcefully disable KVM PV features not exposed in guest CPUIDs */ + bool kvm_pv_enforce_cpuid; + /* Number of physical address bits supported */ uint32_t phys_bits; =20 diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 59ed8327ac13..452b04f469b5 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -1617,6 +1617,16 @@ int kvm_arch_init_vcpu(CPUState *cs) =20 cpu_x86_cpuid(env, 0, 0, &limit, &unused, &unused, &unused); =20 + if (cpu->kvm_pv_enforce_cpuid) { + r =3D kvm_vcpu_enable_cap(cs, KVM_CAP_ENFORCE_PV_FEATURE_CPUID, 0,= 1); + if (r < 0) { + fprintf(stderr, + "failed to enable KVM_CAP_ENFORCE_PV_FEATURE_CPUID: %s= ", + strerror(-r)); + abort(); + } + } + for (i =3D 0; i <=3D limit; i++) { if (cpuid_i =3D=3D KVM_MAX_CPUID_ENTRIES) { fprintf(stderr, "unsupported level value: 0x%x\n", limit); --=20 2.31.1