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    Subject[PATCH 18/23] KVM: SVM: Don't manually emulate RDPMC if nrips=0
    Date
    From: Sean Christopherson <seanjc@google.com>

    Remove bizarre code that causes KVM to run RDPMC through the emulator
    when nrips is disabled. Accelerated emulation of RDPMC doesn't rely on
    any additional data from the VMCB, and SVM has generic handling for
    updating RIP to skip instructions when nrips is disabled.

    Signed-off-by: Sean Christopherson <seanjc@google.com>
    Message-Id: <20210205005750.3841462-9-seanjc@google.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    ---
    arch/x86/kvm/svm/svm.c | 10 +---------
    1 file changed, 1 insertion(+), 9 deletions(-)

    diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
    index 8cb31603bce5..3725a4636930 100644
    --- a/arch/x86/kvm/svm/svm.c
    +++ b/arch/x86/kvm/svm/svm.c
    @@ -2424,14 +2424,6 @@ static int rsm_interception(struct kvm_vcpu *vcpu)
    return kvm_emulate_instruction_from_buffer(vcpu, rsm_ins_bytes, 2);
    }

    -static int rdpmc_interception(struct kvm_vcpu *vcpu)
    -{
    - if (!nrips)
    - return emulate_on_interception(vcpu);
    -
    - return kvm_emulate_rdpmc(vcpu);
    -}
    -
    static bool check_selective_cr0_intercepted(struct kvm_vcpu *vcpu,
    unsigned long val)
    {
    @@ -3058,7 +3050,7 @@ static int (*const svm_exit_handlers[])(struct kvm_vcpu *vcpu) = {
    [SVM_EXIT_SMI] = kvm_emulate_as_nop,
    [SVM_EXIT_INIT] = kvm_emulate_as_nop,
    [SVM_EXIT_VINTR] = interrupt_window_interception,
    - [SVM_EXIT_RDPMC] = rdpmc_interception,
    + [SVM_EXIT_RDPMC] = kvm_emulate_rdpmc,
    [SVM_EXIT_CPUID] = kvm_emulate_cpuid,
    [SVM_EXIT_IRET] = iret_interception,
    [SVM_EXIT_INVD] = kvm_emulate_invd,
    --
    2.26.2

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