From: Avi Kivity <avi@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: aliguori@us.ibm.com, "Michael S. Tsirkin" <mst@redhat.com>,
aik@ozlabs.ru, rusty@rustcorp.com.au, agraf@suse.de,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] virtio: Make memory barriers be memory barriers
Date: Tue, 06 Sep 2011 12:28:40 +0300 [thread overview]
Message-ID: <4E65E7C8.4080602@redhat.com> (raw)
In-Reply-To: <4E65C3EE.1090407@redhat.com>
On 09/06/2011 09:55 AM, Paolo Bonzini wrote:
> On 09/06/2011 05:12 AM, David Gibson wrote:
>> I'm not "fixing ppc". I'm fixing a fundamental flaw in the protocol
>> implementation._So far_ I've only observed the effects on ppc, but
>> that doesn't mean they don't exist.
>
> Actually Michael is right. The implementation is correct on x86,
> though wrong anywhere else (perhaps s390?). On those architectures
> you do not need rmb() and wmb().
Are we sure? Nothing prevents the guest from using weakly-ordered
writes, is there? For example, using MOVNTDQ.
Although in that case the guest is probably required to issue an SFENCE.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2011-09-06 9:28 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-01 6:09 [Qemu-devel] [PATCH] virtio: Make memory barriers be memory barriers David Gibson
2011-09-01 6:47 ` Paolo Bonzini
2011-09-02 0:08 ` David Gibson
2011-09-02 6:49 ` Paolo Bonzini
2011-09-03 11:53 ` Blue Swirl
2011-09-01 7:37 ` Sasha Levin
2011-09-01 7:38 ` Sasha Levin
2011-09-01 7:56 ` Paolo Bonzini
2011-09-02 0:09 ` David Gibson
2011-09-01 15:30 ` Michael S. Tsirkin
2011-09-01 16:14 ` Paolo Bonzini
2011-09-01 16:34 ` Michael S. Tsirkin
2011-09-01 20:31 ` Paolo Bonzini
2011-09-02 15:45 ` Michael S. Tsirkin
2011-09-03 14:46 ` David Gibson
2011-09-04 9:16 ` Michael S. Tsirkin
2011-09-05 4:43 ` David Gibson
2011-09-05 9:19 ` Michael S. Tsirkin
2011-09-06 3:12 ` David Gibson
2011-09-06 6:55 ` Paolo Bonzini
2011-09-06 9:02 ` David Gibson
2011-09-06 9:28 ` Avi Kivity [this message]
2011-09-06 9:35 ` Michael S. Tsirkin
2011-09-06 9:38 ` Paolo Bonzini
2011-09-05 7:41 ` Paolo Bonzini
2011-09-05 8:06 ` Michael S. Tsirkin
2011-09-05 9:42 ` Paolo Bonzini
2011-09-03 16:19 ` Paolo Bonzini
2011-09-04 8:47 ` Michael S. Tsirkin
2011-09-02 0:11 ` David Gibson
2011-09-02 6:11 ` Paolo Bonzini
2011-09-02 15:57 ` Michael S. Tsirkin
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