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    Subject[PATCH v3 7/8] kvm: x86: Emulate MSR IA32_CORE_CAPABILITIES
    Date
    Emulate MSR_IA32_CORE_CAPABILITIES in software and unconditionally
    advertise its support to userspace. Like MSR_IA32_ARCH_CAPABILITIES, it
    is a feature-enumerating MSR and can be fully emulated regardless of
    hardware support. Existence of CORE_CAPABILITIES is enumerated via
    CPUID.(EAX=7H,ECX=0):EDX[30].

    Note, support for individual features enumerated via CORE_CAPABILITIES,
    e.g., split lock detection, will be added in future patches.

    Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
    ---
    arch/x86/include/asm/kvm_host.h | 1 +
    arch/x86/kvm/cpuid.c | 5 +++--
    arch/x86/kvm/x86.c | 22 ++++++++++++++++++++++
    3 files changed, 26 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
    index 329d01c689b7..dc231240102f 100644
    --- a/arch/x86/include/asm/kvm_host.h
    +++ b/arch/x86/include/asm/kvm_host.h
    @@ -591,6 +591,7 @@ struct kvm_vcpu_arch {
    u64 ia32_xss;
    u64 microcode_version;
    u64 arch_capabilities;
    + u64 core_capabilities;

    /*
    * Paging state of the vcpu
    diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
    index b1c469446b07..7282d04f3a6b 100644
    --- a/arch/x86/kvm/cpuid.c
    +++ b/arch/x86/kvm/cpuid.c
    @@ -409,10 +409,11 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
    boot_cpu_has(X86_FEATURE_AMD_SSBD))
    entry->edx |= F(SPEC_CTRL_SSBD);
    /*
    - * We emulate ARCH_CAPABILITIES in software even
    - * if the host doesn't support it.
    + * ARCH_CAPABILITIES and CORE_CAPABILITIES are emulated in
    + * software regardless of host support.
    */
    entry->edx |= F(ARCH_CAPABILITIES);
    + entry->edx |= F(CORE_CAPABILITIES);
    break;
    case 1:
    entry->eax &= kvm_cpuid_7_1_eax_x86_features;
    diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    index fab4d25575bf..ed16644289a3 100644
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -1222,6 +1222,7 @@ static const u32 emulated_msrs_all[] = {
    MSR_IA32_TSC_ADJUST,
    MSR_IA32_TSCDEADLINE,
    MSR_IA32_ARCH_CAPABILITIES,
    + MSR_IA32_CORE_CAPS,
    MSR_IA32_MISC_ENABLE,
    MSR_IA32_MCG_STATUS,
    MSR_IA32_MCG_CTL,
    @@ -1288,6 +1289,7 @@ static const u32 msr_based_features_all[] = {
    MSR_F10H_DECFG,
    MSR_IA32_UCODE_REV,
    MSR_IA32_ARCH_CAPABILITIES,
    + MSR_IA32_CORE_CAPS,
    };

    static u32 msr_based_features[ARRAY_SIZE(msr_based_features_all)];
    @@ -1341,12 +1343,20 @@ static u64 kvm_get_arch_capabilities(void)
    return data;
    }

    +static u64 kvm_get_core_capabilities(void)
    +{
    + return 0;
    +}
    +
    static int kvm_get_msr_feature(struct kvm_msr_entry *msr)
    {
    switch (msr->index) {
    case MSR_IA32_ARCH_CAPABILITIES:
    msr->data = kvm_get_arch_capabilities();
    break;
    + case MSR_IA32_CORE_CAPS:
    + msr->data = kvm_get_core_capabilities();
    + break;
    case MSR_IA32_UCODE_REV:
    rdmsrl_safe(msr->index, &msr->data);
    break;
    @@ -2716,6 +2726,11 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
    return 1;
    vcpu->arch.arch_capabilities = data;
    break;
    + case MSR_IA32_CORE_CAPS:
    + if (!msr_info->host_initiated)
    + return 1;
    + vcpu->arch.core_capabilities = data;
    + break;
    case MSR_EFER:
    return set_efer(vcpu, msr_info);
    case MSR_K7_HWCR:
    @@ -3044,6 +3059,12 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
    return 1;
    msr_info->data = vcpu->arch.arch_capabilities;
    break;
    + case MSR_IA32_CORE_CAPS:
    + if (!msr_info->host_initiated &&
    + !guest_cpuid_has(vcpu, X86_FEATURE_CORE_CAPABILITIES))
    + return 1;
    + msr_info->data = vcpu->arch.core_capabilities;
    + break;
    case MSR_IA32_POWER_CTL:
    msr_info->data = vcpu->arch.msr_ia32_power_ctl;
    break;
    @@ -9282,6 +9303,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
    goto free_guest_fpu;

    vcpu->arch.arch_capabilities = kvm_get_arch_capabilities();
    + vcpu->arch.core_capabilities = kvm_get_core_capabilities();
    vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT;
    kvm_vcpu_mtrr_init(vcpu);
    vcpu_load(vcpu);
    --
    2.23.0
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