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From: Paul Mackerras <paulus@ozlabs.org>
To: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Cc: kvm-ppc@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH] KVM: PPC: Book3S HV: Save/restore vrsave register in kvmhv_p9_guest_entry()
Date: Tue, 30 Apr 2019 20:08:52 +1000	[thread overview]
Message-ID: <20190430100852.GI32205@blackberry> (raw)
In-Reply-To: <20190430004123.1189-1-sjitindarsingh@gmail.com>

On Tue, Apr 30, 2019 at 10:41:23AM +1000, Suraj Jitindar Singh wrote:
> On POWER9 and later processors where the host can schedule vcpus on a
> per thread basis, there is a streamlined entry path used when the guest
> is radix. This entry path saves/restores the fp and vr state in
> kvmhv_p9_guest_entry() by calling store_[fp/vr]_state() and
> load_[fp/vr]_state(). This is the same as the old entry path however the
> old entry path also saved/restored the VRSAVE register, which isn't done
> in the new entry path.
> 
> This means that the vrsave register is now volatile across guest exit,
> which is an incorrect change in behaviour.
> 
> Fix this by saving/restoring the vrsave register in kvmhv_p9_guest_entry().
> This restores the old, correct, behaviour.
> 
> Fixes: 95a6432ce9038 ("KVM: PPC: Book3S HV: Streamlined guest entry/exit path on P9 for radix guests")
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>

Thanks, patch applied to my kvm-ppc-next tree.

Paul.

      reply	other threads:[~2019-04-30 10:12 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-30  0:41 [PATCH] KVM: PPC: Book3S HV: Save/restore vrsave register in kvmhv_p9_guest_entry() Suraj Jitindar Singh
2019-04-30 10:08 ` Paul Mackerras [this message]

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