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From: Paolo Bonzini <pbonzini@redhat.com>
To: David Hildenbrand <david@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 09:34:20 +0100	[thread overview]
Message-ID: <d1aa3e79-7538-6671-dbff-04a3b000bfe5@redhat.com> (raw)
In-Reply-To: <6f73cff1-eddf-7dc6-a93c-31c20e8520d7@redhat.com>

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.

Paolo

  parent reply	other threads:[~2017-11-15  8:34 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 [this message]
2017-11-15  9:23         ` David Hildenbrand
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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