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    Subject[PATCH MANUALSEL 5.14 3/5] KVM: VMX: Remove redundant handling of bus lock vmexit
    Date
    From: Hao Xiang <hao.xiang@linux.alibaba.com>

    [ Upstream commit d61863c66f9b443192997613cd6aeca3f65cc313 ]

    Hardware may or may not set exit_reason.bus_lock_detected on BUS_LOCK
    VM-Exits. Dealing with KVM_RUN_X86_BUS_LOCK in handle_bus_lock_vmexit
    could be redundant when exit_reason.basic is EXIT_REASON_BUS_LOCK.

    We can remove redundant handling of bus lock vmexit. Unconditionally Set
    exit_reason.bus_lock_detected in handle_bus_lock_vmexit(), and deal with
    KVM_RUN_X86_BUS_LOCK only in vmx_handle_exit().

    Signed-off-by: Hao Xiang <hao.xiang@linux.alibaba.com>
    Message-Id: <1634299161-30101-1-git-send-email-hao.xiang@linux.alibaba.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/x86/kvm/vmx/vmx.c | 15 +++++++++------
    1 file changed, 9 insertions(+), 6 deletions(-)

    diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
    index 55de1eb135f9..87150b3c9c5f 100644
    --- a/arch/x86/kvm/vmx/vmx.c
    +++ b/arch/x86/kvm/vmx/vmx.c
    @@ -5551,9 +5551,13 @@ static int handle_encls(struct kvm_vcpu *vcpu)

    static int handle_bus_lock_vmexit(struct kvm_vcpu *vcpu)
    {
    - vcpu->run->exit_reason = KVM_EXIT_X86_BUS_LOCK;
    - vcpu->run->flags |= KVM_RUN_X86_BUS_LOCK;
    - return 0;
    + /*
    + * Hardware may or may not set the BUS_LOCK_DETECTED flag on BUS_LOCK
    + * VM-Exits. Unconditionally set the flag here and leave the handling to
    + * vmx_handle_exit().
    + */
    + to_vmx(vcpu)->exit_reason.bus_lock_detected = true;
    + return 1;
    }

    /*
    @@ -6039,9 +6043,8 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
    int ret = __vmx_handle_exit(vcpu, exit_fastpath);

    /*
    - * Even when current exit reason is handled by KVM internally, we
    - * still need to exit to user space when bus lock detected to inform
    - * that there is a bus lock in guest.
    + * Exit to user space when bus lock detected to inform that there is
    + * a bus lock in guest.
    */
    if (to_vmx(vcpu)->exit_reason.bus_lock_detected) {
    if (ret > 0)
    --
    2.33.0
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