On 01/11/2018 00:40, Tian, Kevin wrote: >> From: Tian, Kevin >> Sent: Tuesday, October 30, 2018 3:00 PM >> >>> From: Jan Beulich [mailto:jbeul...@suse.com] >>> Sent: Thursday, October 25, 2018 9:58 PM >>> >>>>>> On 25.10.18 at 15:02, <andrew.coop...@citrix.com> wrote: >>>> On 25/10/18 13:51, Jan Beulich wrote: >>>>>>>> On 15.10.18 at 14:06, <andrew.coop...@citrix.com> wrote: >>>>>> From the debugging, we see that PPR/IRR/ISR appear to retain their >>> state >>>>>> across the mwait, and there is nothing in the manual which I can see >>>>>> discussing the interaction of LAPIC state and C states. >>>>> Is it perhaps a bad idea to go idle with an un-acked interrupt? >>>> Most likely. >>>> >>>> Then again, going idle with an un-acked line interrupt does appear to >>>> work. It is only un-acked edge interrupts which appear to hit this issue. >>> Well, non-maskable MSI are the only ones (outside of "new" IO-APIC >>> ack mode, which should not be used on recent hardware because of >>> directed EOI presumably being available everywhere) where the ack >>> gets deferred until the .end hook (i.e. after the handler was run). >>> IOW AFAICT line interrupts would never be pending when we go idle. >>> >>>> Still - I'd prefer some guidance from the hardware folk as to what can >>>> realistically be expected here. >>> Fully agree. >> Just sent a mail internally to get clarification. >> > One question. > > in the first mail, Roger mentioned: > -- > The issue is caused by what seems to be an interrupt injection while > Xen is still servicing a previous interrupt (ie: the interrupt hasn't > been EOI'ed and ISR for the vector is set) with **the same or lower > priority** than the interrupt currently being serviced. > -- > > from the debug log, it's actually the exact same vector (0x21) as > what is being in service in peoi stack.
Yes - the problem is a repeat delivery of an interrupt which Xen thinks it is already in the middle of processing. > > Do you actually see the scenario "with the same or lower priority"? > If yes, can you post the debug log too? I'm afraid that I don't understand the question. A repeat delivery of vector 0x21 is the same priority. I haven't seen an example of a lower priority interrupt being accepted, but that might just be down to the repro scenario. Unfortunately, XTF isn't usable on native hardware yet so I can't experiment cleanly in this area. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel