From: Ian Campbell <Ian.Campbell@citrix.com>
To: Ashish Bijlani <ashish.bijlani@gmail.com>
Cc: xen-devel@lists.xensource.com
Subject: Re: do_iret bug in xen
Date: Tue, 27 Nov 2007 23:17:16 +0000 [thread overview]
Message-ID: <1196205436.29110.26.camel@localhost.localdomain> (raw)
In-Reply-To: <ec55b17e0711271441l6145399fu963553fceb67694e@mail.gmail.com>
On Tue, 2007-11-27 at 17:41 -0500, Ashish Bijlani wrote:
> "cpumask_raise_softirq(mask, SCHEDULE_SOFTIRQ)" sends an IPI to the
> target processor, this can cause current to change.
No it can't.
The IPI causes smp_event_check_interrupt() to be called which just ACKs
the IPI and returns via ret_from_intr (in entry.S). It is only if a
guest was interrupted that we go down the test_all_events path which
processes softirqs. If it was Xen which was interrupted then we go to
restore_all_xen which just returns to Xen. In this case Xen will
eventually return to the guest and take the test_all_events path and
process the softirq.
Ian.
next prev parent reply other threads:[~2007-11-27 23:17 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <E1Ix7Vw-000810-RL@host-192-168-0-1-bcn-london>
2007-11-27 21:50 ` do_iret bug in xen Andres Lagar-Cavilla
2007-11-27 22:41 ` Ashish Bijlani
2007-11-27 23:17 ` Ian Campbell [this message]
2007-11-27 23:30 ` Ashish Bijlani
2007-11-28 0:51 ` Daniel Stodden
2007-11-28 1:15 ` Ashish Bijlani
2007-11-28 1:37 ` Daniel Stodden
2007-11-27 18:59 Ashish Bijlani
2007-11-27 19:16 ` Daniel Stodden
2007-11-27 19:28 ` Ashish Bijlani
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