On 23.02.21 10:26, Ross Lagerwall wrote:
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@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>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?
Sorry it took so long, but now I was able to look into this issue. I have managed to reproduce it with a pv Linux guest. I'm now adding some debug code to understand what is happening there. Juergen
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