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From: "Jan Beulich" <JBeulich@suse.com>
To: andres@lagarcavilla.org
Cc: Keir Fraser <keir@xen.org>,
	"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
	Xudong Hao <xudong.hao@intel.com>,
	Xiantao Zhang <xiantao.zhang@intel.com>, Tim Deegan <tim@xen.org>
Subject: Re: Deadlocks by p2m_lock and event_lock
Date: Wed, 14 Mar 2012 09:20:53 +0000	[thread overview]
Message-ID: <4F6071050200007800078384@nat28.tlf.novell.com> (raw)
In-Reply-To: <109443395be5f3e323fa7d0d1977f8b6.squirrel@webmail.lagarcavilla.org>

>>> On 13.03.12 at 19:26, "Andres Lagar-Cavilla" <andres@lagarcavilla.org> wrote:
>>  Hi, Tim and Andres
>> The patch fix part of this issue. In handle_mmio, function hvmemul_do_io()
>> is called and p2m lock was held again by calling get_gfn_unshare(), still
>> trigger a deadlocks.
> 
> I have a question before I dive into lock untangling
> 
> msix_capability_init ->
> p2m_change_entry_type_global(dev->domain, p2m_mmio_direct, p2m_mmio_direct);
> 
> Huh? This achieves ... nothing. Almost. It flushes a bunch of TLBs, but
> that can be done with significantly less effort. Am I missing something?

Yes - the purpose of this isn't to flush any TLBs, but to enforce the
immediately preceding addition to the mmio_ro_ranges range set.

Jan

  reply	other threads:[~2012-03-14  9:20 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-09 10:58 Deadlocks by p2m_lock and event_lock Hao, Xudong
2012-03-09 11:20 ` Tim Deegan
2012-03-09 11:44   ` Hao, Xudong
2012-03-09 16:29     ` Andres Lagar-Cavilla
2012-03-09 16:55       ` Tim Deegan
2012-03-13  7:51         ` Hao, Xudong
2012-03-13 15:27           ` Andres Lagar-Cavilla
2012-03-13 18:26           ` Andres Lagar-Cavilla
2012-03-14  9:20             ` Jan Beulich [this message]
2012-03-14 14:18               ` Andres Lagar-Cavilla
2012-03-13 18:45           ` Andres Lagar-Cavilla
2012-03-14  7:12             ` Hao, Xudong
2012-03-14  8:28               ` Zhang, Yang Z
2012-03-14 14:20               ` Andres Lagar-Cavilla
2012-03-14 15:10               ` Andres Lagar-Cavilla
2012-03-15  2:19                 ` Hao, Xudong
2012-03-15  3:37                   ` Andres Lagar-Cavilla
2012-03-15 10:44                   ` Tim Deegan

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