From: Scott Wood <scottwood@freescale.com>
To: kvm-ppc@vger.kernel.org
Subject: Re: [PATCH 3/5] KVM: PPC: Paravirtualize SPRG4-7, ESR, PIR, MASn
Date: Mon, 19 Sep 2011 16:05:06 +0000 [thread overview]
Message-ID: <4E776832.8000502@freescale.com> (raw)
In-Reply-To: <20110826233142.GC30607@schlenkerla.am.freescale.net>
On 09/19/2011 04:23 AM, Alexander Graf wrote:
>
> On 15.09.2011, at 20:26, Scott Wood wrote:
>
>> However, I think it could work reasonably well to use this as the
>> backing store instead of vcpu->arch.sprg4-7. The guest would still see
>> inconsistency if it writes to paravirt and then reads from the hw reg
>> without an intervening exit, so that restriction on use still applies,
>> but qemu would see the right thing in sregs, and we wouldn't have the
>> duplication.
>
> Yes, also guest user space would still be fine when guest kernel space writes to the PV reg.
We'd be relying on the fact that there's always an intervening exit to
do rfi without E.HV, and that the guest has direct read/write access
(thus no paravirt) with E.HV. Will make a note of that in the comments.
-Scott
prev parent reply other threads:[~2011-09-19 16:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-26 23:31 [PATCH 3/5] KVM: PPC: Paravirtualize SPRG4-7, ESR, PIR, MASn Scott Wood
2011-09-05 22:28 ` Alexander Graf
2011-09-15 18:26 ` Scott Wood
2011-09-19 9:23 ` Alexander Graf
2011-09-19 16:05 ` Scott Wood [this message]
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