[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v6 0/3] XSA-343 followup patches
On 18.11.2020 09:41, Jürgen Groß wrote: > On 18.11.20 09:22, Jan Beulich wrote: >> On 17.11.2020 19:13, Julien Grall wrote: >>> On 09/11/2020 16:38, Juergen Gross wrote: >>>> Juergen Gross (3): >>>> xen/events: access last_priority and last_vcpu_id together >>>> xen/evtchn: rework per event channel lock >>>> xen/evtchn: revert 52e1fc47abc3a0123 >>> >>> While looking at the list of commits, I noticed that the first patch >>> hasn't been committed. They were all acked/reviewed, so I am a bit >>> puzzled why this was omitted... >>> >>> I have nearly missed as I was expecting the 3 patches to be committed >>> together. May I suggest that in the future we reply to the cover letter >>> and mention which patches are (or not) committed? >>> >>> Regarding patch #1, I will commit it tomorrow unless there are strong >>> objections against. >> >> Without a clear outline of what would break with the present logic, >> I had previously indicated I'm not convinced of the change. This >> isn't a strong objection, no, but I still wouldn't want to see my >> name associated with it in such a case. Furthermore I clearly view >> this as not a backporting candidate, while the other two are (as I >> did previously indicate). Hence the latter two patches wanted >> re-basing ahead of the first one anyway, to ease the backports. > > Consider an NMI during evtchn_fifo_set_pending() between updating > last_vcpu_id and last_priority, while on another cpu a concurrent > evtchn_fifo_set_pending() is being called. On that other cpu > lock_old_queue() might return a wrong queue as it will read only > the new last_vcpu_id, but not the new last_priority value. Which has become possible only as of patch 2 of this series, i.e. this one really was a prereq without its description making this clear. Now that it'll go in on top of the other two, there's no strict need to change the description anymore, though. But I take from this that I should also queue it up for backporting then. Jan
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