From: David Hildenbrand <david@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>, Rik van Riel <riel@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
tglx@linutronix.de, rkrcmar@redhat.com, borntraeger@de.ibm.com
Subject: Re: [PATCH] x86,kvm: move qemu/guest FPU switching out to vcpu_run
Date: Wed, 15 Nov 2017 10:23:46 +0100 [thread overview]
Message-ID: <980be73e-828d-d844-d2ab-ea91ec2844e6@redhat.com> (raw)
In-Reply-To: <d1aa3e79-7538-6671-dbff-04a3b000bfe5@redhat.com>
On 15.11.2017 09:34, Paolo Bonzini wrote:
> On 14/11/2017 20:40, David Hildenbrand wrote:
>> I think we should check all get/put_fpu callers if they need
>> preempt_disable().
>>
>> E.g. em_fxrstor() needs disabled preemption as we temporarily
>> save + restore some host register (via fxsave + fxrstor) under some
>> circumstances that are not saved/restored when switching to/back from
>> another process. We should double check.
>
> Rik may correct me, but I believe that you don't need
> preempt_disable/enable because preempt notifiers do this for you.
>
Seems to boil down to what Wanpeng Li asked about preempt notifiers in
response to v2.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2017-11-15 9:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-14 5:12 [PATCH] x86,kvm: move qemu/guest FPU switching out to vcpu_run Rik van Riel
2017-11-14 16:57 ` David Hildenbrand
2017-11-14 18:07 ` Rik van Riel
2017-11-14 18:09 ` Paolo Bonzini
2017-11-14 19:40 ` David Hildenbrand
2017-11-14 21:11 ` Rik van Riel
2017-11-15 8:34 ` Paolo Bonzini
2017-11-15 9:23 ` David Hildenbrand [this message]
2017-11-15 14:50 ` Rik van Riel
2017-11-15 15:20 ` David Hildenbrand
2017-12-04 2:15 ` Wanpeng Li
2017-12-05 17:09 ` Radim Krcmar
2017-12-06 2:48 ` Wanpeng Li
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