linux-kernel - Re: [PATCH 1/2] KVM: x86: set TMR when the interrupt is accepted

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Message-ID: <55CC47E4.5090200@redhat.com>
Date:	Thu, 13 Aug 2015 09:31:48 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	"Zhang, Yang Z" <yang.z.zhang@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>
Cc:	"alex.williamson@...hat.com" <alex.williamson@...hat.com>,
	"srutherford@...el.com" <srutherford@...el.com>,
	"Gudimetla, Giridhar Kumar" <giridhar.kumar.gudimetla@...el.com>,
	"Nakajima, Jun" <jun.nakajima@...el.com>
Subject: Re: [PATCH 1/2] KVM: x86: set TMR when the interrupt is accepted



On 13/08/2015 08:35, Zhang, Yang Z wrote:
>> You may be right. It is safe if no future hardware plans to use
>> it. Let me check with our hardware team to see whether it will be
>> used or not in future.
> 
> After checking with Jun, there is no guarantee that the guest running
> on another CPU will operate properly if hypervisor modify the vTMR
> from another CPU. So the hypervisor should not to do it.

I guess I can cause a vmexit on level-triggered interrupts, it's not a
big deal, but no weasel words, please.

What's going to break, and where is it documented?

Paolo
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