linux-kernel - Re: [PATCH v2] X86/VMX: Disable VMX preemption timer if MWAIT is not intercepted

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Date:   Tue, 10 Apr 2018 12:16:53 +0000
From:   "Raslan, KarimAllah" <karahmed@...zon.de>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>
CC:     "tglx@...utronix.de" <tglx@...utronix.de>,
        "hpa@...or.com" <hpa@...or.com>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH v2] X86/VMX: Disable VMX preemption timer if MWAIT is not
 intercepted

On Tue, 2018-04-10 at 13:07 +0200, Paolo Bonzini wrote:
> On 10/04/2018 12:08, KarimAllah Ahmed wrote:
> > 
> > @@ -11908,6 +11908,9 @@ static int vmx_set_hv_timer(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc)
> >  	u64 guest_tscl = kvm_read_l1_tsc(vcpu, tscl);
> >  	u64 delta_tsc = max(guest_deadline_tsc, guest_tscl) - guest_tscl;
> >  
> > +	if (kvm_pause_in_guest(vcpu->kvm))
> > +		return -EOPNOTSUPP;
> > +
> 
> This is still doing a relatively expensive kvm_read_l1_tsc, so move it
> even further up. :)

hehe .. done in v3 :)

> 
> Paolo
> 
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