linux-kernel - Re: [PATCH v2 3/3] KVM: vmx: handle vm-exit for UMWAIT and TPAUSE

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Date:   Wed, 29 May 2019 03:28:19 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Tao Xu <tao3.xu@...el.com>, rkrcmar@...hat.com, corbet@....net,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        sean.j.christopherson@...el.com
Cc:     x86@...nel.org, kvm@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, jingqi.liu@...el.com
Subject: Re: [PATCH v2 3/3] KVM: vmx: handle vm-exit for UMWAIT and TPAUSE

On 24/05/19 09:56, Tao Xu wrote:
> As the latest Intel 64 and IA-32 Architectures Software Developer's
> Manual, UMWAIT and TPAUSE instructions cause a VM exit if the
> “RDTSC exiting” and “enable user wait and pause” VM-execution controls
> are both 1.
> 
> This patch is to handle the vm-exit for UMWAIT and TPAUSE as invalid_op.

KVM never enables RDTSC exiting, so this is not necessary.

Paolo