Subject: Re: [PATCH 1/3] Implement emulator_write_phys()
From: Anthony Liguori <aliguori@us.ibm.com>
To: Avi Kivity <avi@qumranet.com>
Cc: kvm-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
In-Reply-To: <46D2F1B7.70604@qumranet.com>
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Organization: IBM
Date: Mon, 27 Aug 2007 12:23:39 -0500
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On Mon, 2007-08-27 at 18:45 +0300, Avi Kivity wrote:
> Anthony Liguori wrote:
> > Since a hypercall may span two pages and is a gva, we need a function to write
> > to a gva that may span multiple pages.  emulator_write_phys() seems like the
> > logical choice for this.
> >
> > @@ -962,8 +962,35 @@ static int emulator_write_std(unsigned long addr,
> >  			      unsigned int bytes,
> >  			      struct kvm_vcpu *vcpu
> 
> I think that emulator_write_emulated(), except for being awkwardly 
> named, should do the job.  We have enough APIs.
> 
> But!  We may not overwrite the hypercall instruction while a vcpu may be 
> executing, since there's no atomicity guarantee for code fetch.  We have 
> to to be out of guest mode while writing that insn.


Hrm, good catch.

How can we get out of guest mode given SMP guest support?

Regards,

Anthony Liguori

> 
> 

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