From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:37358)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <alex.bennee@linaro.org>) id 1cvNcJ-0007Qb-Op
	for qemu-devel@nongnu.org; Tue, 04 Apr 2017 08:31:24 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <alex.bennee@linaro.org>) id 1cvNcG-00087Q-Jr
	for qemu-devel@nongnu.org; Tue, 04 Apr 2017 08:31:23 -0400
Received: from mail-wr0-x22e.google.com ([2a00:1450:400c:c0c::22e]:34332)
	by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16)
	(Exim 4.71) (envelope-from <alex.bennee@linaro.org>)
	id 1cvNcG-00085k-DP
	for qemu-devel@nongnu.org; Tue, 04 Apr 2017 08:31:20 -0400
Received: by mail-wr0-x22e.google.com with SMTP id t20so8371905wra.1
	for <qemu-devel@nongnu.org>; Tue, 04 Apr 2017 05:31:20 -0700 (PDT)
References: <20170403124524.10824-1-alex.bennee@linaro.org>
	<20170403124524.10824-8-alex.bennee@linaro.org>
	<000201d2ad05$e28626d0$a7927470$@ru>
	<8760ikblf7.fsf@linaro.org> <874ly4bgbu.fsf@linaro.org>
	<3c4f3f42-3b33-8e0a-b3f4-0963670b47de@redhat.com>
From: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
In-reply-to: <3c4f3f42-3b33-8e0a-b3f4-0963670b47de@redhat.com>
Date: Tue, 04 Apr 2017 13:31:17 +0100
Message-ID: <8737dobbhm.fsf@linaro.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Subject: Re: [Qemu-devel] [RFC PATCH v1 7/9] cpus: move icount preparation
 out of tcg_exec_cpu
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pavel Dovgalyuk <dovgaluk@ispras.ru>, rth@twiddle.net, peter.maydell@linaro.org, qemu-devel@nongnu.org, mttcg@listserver.greensocs.com, fred.konrad@greensocs.com, a.rigo@virtualopensystems.com, cota@braap.org, bobby.prani@gmail.com, nikunj@linux.vnet.ibm.com, 'Peter Crosthwaite' <crosthwaite.peter@gmail.com>


Paolo Bonzini <pbonzini@redhat.com> writes:

> On 04/04/2017 12:46, Alex Bennée wrote:
>>> In theory the main-loop should be sequenced before or after vCPU events
>>> because of the BQL. I'm not sure why this is not currently the case.
>>
>> It seems cpu_handle_exception doesn't take the BQL until
>> replay_exception() has done its thing. This is fixable but the function
>> is a mess so I'm trying to neaten that up first.
>
> Long term neither cpu_handle_exception nor cpu_handle_interrupt need the
> BQL at all.

Well for record/replay they might. Otherwise we end up moving the record
stream on even though a checkpoint might be being written by the
main-loop.

As far as the cc->do_interrupt() stuff is concerned it will be guest
dependant because you could end up in device emulation code down this
path which must be protected by the BQL - the arm_gic code being a good
example.

>
> Paolo


--
Alex Bennée