From 988f7b8bfeffbf521814d1e48c321f7674277512 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Thu, 2 Sep 2021 11:35:25 +0200 Subject: [PATCH] i386: Support KVM_CAP_ENFORCE_PV_FEATURE_CPUID 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 >= 5.10 and is not enabled by default in QEMU. Signed-off-by: Vitaly Kuznetsov Message-Id: <20210902093530.345756-4-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini --- target/i386/cpu.c | 2 ++ target/i386/cpu.h | 3 +++ target/i386/kvm/kvm.c | 10 ++++++++++ 3 files changed, 15 insertions(+) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index cacec605bf..598019de12 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -6860,6 +6860,8 @@ static Property x86_cpu_properties[] = { 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 29552dc2a7..c990150373 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -1802,6 +1802,9 @@ struct X86CPU { /* Stop SMI delivery for migration compatibility with old machines */ bool kvm_no_smi_migration; + /* 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; diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 7f1b060e6d..d6a70c27e5 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -1629,6 +1629,16 @@ int kvm_arch_init_vcpu(CPUState *cs) cpu_x86_cpuid(env, 0, 0, &limit, &unused, &unused, &unused); + if (cpu->kvm_pv_enforce_cpuid) { + r = 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 = 0; i <= limit; i++) { if (cpuid_i == KVM_MAX_CPUID_ENTRIES) { fprintf(stderr, "unsupported level value: 0x%x\n", limit);