linux-kernel - Re: [PATCH] KVM: VMX: Check if bus lock vmexit was preempted

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Date:   Wed, 22 Sep 2021 14:40:45 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Xiaoyao Li <xiaoyao.li@...el.com>,
        Hao Xiang <hao.xiang@...ux.alibaba.com>, kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, chenyi.qiang@...el.com,
        shannon.zhao@...ux.alibaba.com,
        Sean Christopherson <seanjc@...gle.com>
Subject: Re: [PATCH] KVM: VMX: Check if bus lock vmexit was preempted

On 22/09/21 12:32, Xiaoyao Li wrote:
>>
> 
> EXIT_REASON.bus_lock_detected may or may not be set when exit reason == 
> EXIT_REASON_BUS_LOCK. Intel will update ISE or SDM to state it.
> 
> Maybe we can do below in handle_bus_lock_vmexit handler:
> 
>      if (!to_vmx(vcpu)->exit_reason.bus_lock_detected)
>          to_vmx(vcpu)->exit_reason.bus_lock_detected = 1;
> 
> But is manually changing the hardware reported value for software 
> purpose a good thing?

No.  That said, Hao's patch is just making the code clearer; there's no 
behavioral change since the "if" will just redo the same assignments as 
handle_bus_lock_vmexit.

Paolo