From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: kvm crashes with spice while loading qxl
Date: Tue, 08 Mar 2011 10:28:54 +0100
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Cc: Marcelo Tosatti <mtosatti@redhat.com>,
	Jan Kiszka <jan.kiszka@web.de>, xming <xmingske@gmail.com>,
	Gerd Hoffmann <kraxel@redhat.com>, kvm@vger.kernel.org,
	qemu-devel <qemu-devel@nongnu.org>
To: Avi Kivity <avi@redhat.com>
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On 03/08/2011 10:17 AM, Avi Kivity wrote:
>> Memory map can be protected by a read-write lock initially, so that vcpu
>> thread holds it for read. Later can be converted to URCU.
>
> rwlock is insufficient, need a way to force the vcpu off so a writer can
> actually do something.
>
> So we need some kind of priority rwlock where a reader lets the lock
> know how it can force it off in case a writer comes along.

If the reader is the VCPU thread, the VCPU thread can always be bounced 
via qemu_cpu_kick.

Paolo