linux-kernel - Re: [PART1 RFC v2 09/10] svm: Do not intercept CR8 when enable AVIC

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Date:	Mon, 14 Mar 2016 13:09:00 +0700
From:	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
To:	Paolo Bonzini <pbonzini@...hat.com>, <rkrcmar@...hat.com>,
	<joro@...tes.org>, <bp@...en8.de>, <gleb@...nel.org>,
	<alex.williamson@...hat.com>
CC:	<kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<wei@...hat.com>, <sherry.hurwitz@....com>
Subject: Re: [PART1 RFC v2 09/10] svm: Do not intercept CR8 when enable AVIC

Hi

On 03/07/2016 10:39 PM, Paolo Bonzini wrote:
>> +		svm_x86_ops.update_cr8_intercept = NULL;
>> >  	} else {
>> >  		svm_x86_ops.deliver_posted_interrupt = NULL;
>> >  	}
>> >@@ -1116,7 +1119,8 @@ static void init_vmcb(struct vcpu_svm *svm)
>> >  	set_cr_intercept(svm, INTERCEPT_CR0_WRITE);
>> >  	set_cr_intercept(svm, INTERCEPT_CR3_WRITE);
>> >  	set_cr_intercept(svm, INTERCEPT_CR4_WRITE);
>> >-	set_cr_intercept(svm, INTERCEPT_CR8_WRITE);
>> >+	if (!avic)
> Remember that AVIC enabled/disabled must be refreshed when the
> .refresh_apicv_exec_ctrl callback is invoked, so it is not enough to use
> the global variable.
>
> Paolo
>

Good point. I'll fix this.  By the way, how can we enable APICv only in 
certain VM? Does Qemu/KVM have any specific flags that we can pass to 
enable/disable this?

Thanks,
Suravee