From: "Emilio G. Cota" <cota@braap.org>
To: Richard Henderson <rth@twiddle.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
qemu-devel@nongnu.org, kvm@vger.kernel.org,
Eduardo Habkost <ehabkost@redhat.com>
Subject: Re: [PATCH 11/35] target/i386: access cpu->interrupt_request with atomics
Date: Wed, 19 Sep 2018 11:02:20 -0400 [thread overview]
Message-ID: <20180919150220.GA28724@flamenco> (raw)
In-Reply-To: <681e812b-43f2-04b2-f015-489b6154fec8@twiddle.net>
On Tue, Sep 18, 2018 at 14:04:35 -0700, Richard Henderson wrote:
> On 9/17/18 9:30 AM, Emilio G. Cota wrote:
> > cpu_reset(cs);
> > - cs->interrupt_request = sipi;
> > + atomic_mb_set(&cs->interrupt_request, sipi);
> > memcpy(&env->start_init_save, &save->start_init_save,
>
> Why does this need a memory barrier?
>
> Anyway, I think a bare mechanical conversion would be best
> for the first patch and then extra barriers added separately
> and with a description of why.
Almost no corresponding read has a barrier so it's hard to
justify this one. I'll drop it.
Thanks,
Emilio
next prev parent reply other threads:[~2018-09-19 15:02 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-17 16:30 [PATCH 00/35] exec: drop BQL from interrupt handling Emilio G. Cota
2018-09-17 16:30 ` [PATCH 02/35] target/i386: use cpu_reset_interrupt Emilio G. Cota
2018-09-18 20:47 ` Richard Henderson
2018-09-17 16:30 ` [PATCH 11/35] target/i386: access cpu->interrupt_request with atomics Emilio G. Cota
2018-09-18 21:04 ` Richard Henderson
2018-09-19 15:02 ` Emilio G. Cota [this message]
2018-09-17 16:31 ` [PATCH 32/35] target/i386/kvm: do not acquire the BQL to call cpu_reset_interrupt Emilio G. Cota
2018-09-18 21:12 ` Richard Henderson
2018-09-19 21:19 ` Philippe Mathieu-Daudé
2018-09-17 16:31 ` [PATCH 34/35] exec: push BQL down to cpu->do_interrupt Emilio G. Cota
2018-09-18 4:11 ` David Gibson
2018-09-18 7:12 ` David Hildenbrand
2018-09-19 16:38 ` Cornelia Huck
2018-09-17 16:31 ` [PATCH 35/35] exec: push BQL down to cpu->cpu_exec_interrupt Emilio G. Cota
2018-09-18 4:12 ` David Gibson
2018-09-18 7:48 ` David Hildenbrand
2018-09-18 9:51 ` [PATCH 00/35] exec: drop BQL from interrupt handling David Hildenbrand
2018-09-20 20:05 ` Mark Cave-Ayland
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