linux-kernel - Re: [PATCH] x86: kvm: reset the bootstrap processor when it gets an INIT

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Date:	Sun, 10 Mar 2013 20:10:36 +0200
From:	Gleb Natapov <gleb@...hat.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	mtosatti@...hat.com, jan.kiszka@...mens.com
Subject: Re: [PATCH] x86: kvm: reset the bootstrap processor when it gets an
 INIT

On Sun, Mar 10, 2013 at 06:19:07PM +0100, Paolo Bonzini wrote:
> Il 10/03/2013 16:35, Gleb Natapov ha scritto:
> >> > However, it would effectively redefine the meaning of
> >> > KVM_MP_STATE_INIT_RECEIVED and KVM_MP_STATE_SIPI_RECEIVED, respectively
> >> > to KVM_MP_STATE_WAIT_FOR_SIPI and KVM_MP_STATE_RESETTING.  I wasn't sure
> >> > if this is considered an API change (personally, I would treat it as one).
> >> > 
> > If it is kernel module internal it definitely is not API change.
> > INIT/SIPI handling is a bit ad-hoc right now anyway as Jan noticed. For
> > instance INIT does not really resets VCPU. Only after SIPI it is really
> > reset, so KVM_MP_STATE_SIPI_RECEIVED is really KVM_MP_STATE_RESET_ME_RIGHT_NOW
> > state.
> 
> Yeah, and the current definition is ambiguous (without hypervisor
> patches, there's no way to use it as the names would suggest), so
> perhaps the right thing to do is to rename the states (old names kept
> for backwards compatibility only) and work from there.
> 
I do not see how renaming clarify things. From userspace point of view
KVM_MP_STATE_SIPI_RECEIVED does not exists. If AP is hard reset
userspase makes it UNINIT, if soft reset it makes it INIT_RECEIVED, if
BSP it makes it running no matter what type of reset.

--
			Gleb.
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