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From: Ross Lagerwall <ross.lagerwall@citrix.com>
To: Juergen Gross <jgross@suse.com>, <xen-devel@lists.xenproject.org>,
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	<stable@vger.kernel.org>, Julien Grall <julien@xen.org>
Subject: Re: [PATCH v3 2/8] xen/events: don't unmask an event channel when an eoi is pending
Date: Tue, 23 Feb 2021 09:26:49 +0000	[thread overview]
Message-ID: <d368a948-17d6-4e64-110e-bede3158f49f@citrix.com> (raw)
In-Reply-To: <20210219154030.10892-3-jgross@suse.com>

On 2021-02-19 15:40, Juergen Gross wrote:
> An event channel should be kept masked when an eoi is pending for it.
> When being migrated to another cpu it might be unmasked, though.
> In order to avoid this keep three different flags for each event channel
> to be able to distinguish "normal" masking/unmasking from eoi related
> masking/unmasking and temporary masking. The event channel should only
> be able to generate an interrupt if all flags are cleared.
> Cc: stable@vger.kernel.org
> Fixes: 54c9de89895e0a36047 ("xen/events: add a new late EOI evtchn framework")
> Reported-by: Julien Grall <julien@xen.org>
> Signed-off-by: Juergen Gross <jgross@suse.com>

I tested this patch series backported to a 4.19 kernel and found that
when doing a reboot loop of Windows with PV drivers, occasionally it will
end up in a state with some event channels pending and masked in dom0
which breaks networking in the guest.

The issue seems to have been introduced with this patch, though at first
glance it appears correct. I haven't yet looked into why it is happening.
Have you seen anything like this with this patch?


  parent reply	other threads:[~2021-02-23  9:27 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-19 15:40 [PATCH v3 0/8] xen/events: bug fixes and some diagnostic aids Juergen Gross
2021-02-19 15:40 ` [PATCH v3 1/8] xen/events: reset affinity of 2-level event when tearing it down Juergen Gross
2021-02-19 15:40 ` [PATCH v3 2/8] xen/events: don't unmask an event channel when an eoi is pending Juergen Gross
2021-02-20 12:10   ` Julien Grall
2021-02-23  9:26   ` Ross Lagerwall [this message]
2021-03-05 10:53     ` Jürgen Groß
2021-03-06 16:18     ` Jürgen Groß
2021-02-19 15:40 ` [PATCH v3 3/8] xen/events: avoid handling the same event on two cpus at the same time Juergen Gross
2021-02-20 12:12   ` Julien Grall
2021-02-19 15:40 ` [PATCH v3 4/8] xen/netback: fix spurious event detection for common event case Juergen Gross
2021-02-19 15:40 ` [PATCH v3 5/8] xen/events: link interdomain events to associated xenbus device Juergen Gross
2021-02-22 14:50   ` Roger Pau Monné
2021-02-19 15:40 ` [PATCH v3 6/8] xen/events: add per-xenbus device event statistics and settings Juergen Gross
2021-02-19 15:40 ` [PATCH v3 7/8] xen/evtchn: use smp barriers for user event ring Juergen Gross
2021-02-19 15:40 ` [PATCH v3 8/8] xen/evtchn: use READ/WRITE_ONCE() for accessing ring indices Juergen Gross
2021-02-20 20:35   ` Boris Ostrovsky
2021-02-23 15:44 ` [PATCH v3 0/8] xen/events: bug fixes and some diagnostic aids Boris Ostrovsky

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