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    Subject[PATCH v6 18/38] KVM: x86: hyper-v: Introduce fast guest_hv_cpuid_has_l2_tlb_flush() check
    Date
    Introduce a helper to quickly check if KVM needs to handle VMCALL/VMMCALL
    from L2 in L0 to process L2 TLB flush requests.

    Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
    ---
    arch/x86/include/asm/kvm_host.h | 1 +
    arch/x86/kvm/hyperv.c | 6 ++++++
    arch/x86/kvm/hyperv.h | 7 +++++++
    3 files changed, 14 insertions(+)

    diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
    index 5d60c66ee0de..f9a34af0a5cc 100644
    --- a/arch/x86/include/asm/kvm_host.h
    +++ b/arch/x86/include/asm/kvm_host.h
    @@ -642,6 +642,7 @@ struct kvm_vcpu_hv {
    u32 enlightenments_eax; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EAX */
    u32 enlightenments_ebx; /* HYPERV_CPUID_ENLIGHTMENT_INFO.EBX */
    u32 syndbg_cap_eax; /* HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES.EAX */
    + u32 nested_features_eax; /* HYPERV_CPUID_NESTED_FEATURES.EAX */
    } cpuid_cache;

    struct kvm_vcpu_hv_tlb_flush_fifo tlb_flush_fifo[HV_NR_TLB_FLUSH_FIFOS];
    diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
    index 740190917c1c..4396d75588d8 100644
    --- a/arch/x86/kvm/hyperv.c
    +++ b/arch/x86/kvm/hyperv.c
    @@ -2229,6 +2229,12 @@ void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu)
    hv_vcpu->cpuid_cache.syndbg_cap_eax = entry->eax;
    else
    hv_vcpu->cpuid_cache.syndbg_cap_eax = 0;
    +
    + entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_NESTED_FEATURES, 0);
    + if (entry)
    + hv_vcpu->cpuid_cache.nested_features_eax = entry->eax;
    + else
    + hv_vcpu->cpuid_cache.nested_features_eax = 0;
    }

    int kvm_hv_set_enforce_cpuid(struct kvm_vcpu *vcpu, bool enforce)
    diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
    index 7778b3a5913c..2aa6fb7fc599 100644
    --- a/arch/x86/kvm/hyperv.h
    +++ b/arch/x86/kvm/hyperv.h
    @@ -170,6 +170,13 @@ static inline void kvm_hv_vcpu_empty_flush_tlb(struct kvm_vcpu *vcpu, bool is_gu
    kfifo_reset_out(&tlb_flush_fifo->entries);
    }

    +static inline bool guest_hv_cpuid_has_l2_tlb_flush(struct kvm_vcpu *vcpu)
    +{
    + struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
    +
    + return hv_vcpu && (hv_vcpu->cpuid_cache.nested_features_eax & HV_X64_NESTED_DIRECT_FLUSH);
    +}
    +
    static inline bool kvm_hv_is_tlb_flush_hcall(struct kvm_vcpu *vcpu)
    {
    struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
    --
    2.35.3
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