Re: [PATCH v4 2/3] xen/events: don't unmask an event channel when an eoi is pending

[Jürgen Groß <jgross@xxxxxxxx>]

On 08.03.21 21:33, Boris Ostrovsky wrote:
> On 3/6/21 11:18 AM, 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@xxxxxxxxxxxxxxx
> > Fixes: 54c9de89895e0a36047 ("xen/events: add a new late EOI evtchn framework")
> > Reported-by: Julien Grall <julien@xxxxxxx>
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>
> > ---
> > V2:
> > - introduce a lock around masking/unmasking
> > - merge patch 3 into this one (Jan Beulich)
> > V4:
> > - don't set eoi masking flag in lateeoi_mask_ack_dynirq()
>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
>
>
> Ross, are you planning to test this?
Just as another data point: With the previous version of the patches
a reboot loop of a guest needed max 33 reboots to loose network in
my tests (those were IIRC 6 test runs). With this patch version I
stopped the test after about 1300 reboots without having seen any
problems.

Juergen

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