From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH RFC V3 2/4] kvm hypervisor : Add a hypercall to KVM
	hypervisor to support pv-ticketlocks
Date: Wed, 7 Dec 2011 11:39:47 -0200
Message-ID: <20111207133947.GA1708@amt.cnet>
References: <20111130085921.23386.89708.sendpatchset@oc5400248562.ibm.com>
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	<20111207123330.GA32212@amt.cnet> <4EDF6049.2030204@redhat.com>
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To: Avi Kivity <avi@redhat.com>
Cc: Raghavendra K T <raghukt@linux.vnet.ibm.com>, x86@kernel.org, Peter Zijlstra <peterz@infradead.org>, Virtualization <virtualization@lists.linux-foundation.org>, "H. Peter Anvin" <hpa@zytor.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Xen <xen-devel@lists.xensource.com>, Dave Jiang <dave.jiang@intel.com>, KVM <kvm@vger.kernel.org>, Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>, Ingo Molnar <mingo@redhat.com>, Rik van Riel <riel@redhat.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>, Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>, Sasha Levin <levinsasha928@gmail.com>, Sedat Dilek <sedat.dilek@gmail.com>, Thomas Gleixner <tglx@linutronix.de>, Yinghai Lu <yinghai@kernel.org>, Greg Kroah-Hartman <gregkh@suse.de>, LKML <linux-kernel@vger.kernel.org>, Dave Hansen <dave@linux.vnet.ibm.com>, Suzuk
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On Wed, Dec 07, 2011 at 02:47:05PM +0200, Avi Kivity wrote:
> On 12/07/2011 02:33 PM, Marcelo Tosatti wrote:
> > > 
> > > Also Avi pointed that, logically kvm_arch_vcpu_ioctl_set_mpstate should
> > > be called only in vcpu thread, so after further debugging, I noticed
> > > that,  setting vcpuN->mp_state = KVM_MP_STATE_RUNNABLE; is not
> > > necessary.
> > > I 'll remove that in the next patch. Thanks for pointing.
> >
> > In fact you don't need kvm_arch_vcpu_ioctl_set_mpstate either, only the
> > new "kicked" flag.
> 
> If we have a kicked flag, it becomes necessary to live migrate it.
> 
> Maybe we can change KVM_GET_MP_STATE to fold the kicked flag into the mp
> state (converting HALTED into RUNNABLE).

Yep, that works.

> Also I think we can keep the kicked flag in vcpu->requests, no need for
> new storage.

Was going to suggest it but it violates the currently organized
processing of entries at the beginning of vcpu_enter_guest.

That is, this "kicked" flag is different enough from vcpu->requests
processing that a separate variable seems worthwhile (even more
different with convertion to MP_STATE at KVM_GET_MP_STATE).