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Date:   Tue, 30 Apr 2019 20:08:52 +1000
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()
Message-ID: <20190430100852.GI32205@blackberry>
References: <20190430004123.1189-1-sjitindarsingh@gmail.com>
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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.