On Wed, Apr 1, 2015 at 2:49 PM, Radim Krčmář <rkrcmar@xxxxxxxxxx> wrote: > 2015-03-31 21:23+0300, Andrey Korolyov: >> On Tue, Mar 31, 2015 at 9:04 PM, Bandan Das <bsd@xxxxxxxxxx> wrote: >> > Bandan Das <bsd@xxxxxxxxxx> writes: >> >> Andrey Korolyov <andrey@xxxxxxx> writes: >> >> ... >> >>> http://xdel.ru/downloads/kvm-e5v2-issue/another-tracepoint-fail-with-apicv.dat.gz >> >>> >> >>> Something a bit more interesting, but the mess is happening just >> >>> *after* NMI firing. >> >> >> >> What happens if NMI is turned off on the host ? >> > >> > Sorry, I meant the watchdog.. >> >> Thanks, everything goes well (as it probably should go there): >> http://xdel.ru/downloads/kvm-e5v2-issue/apicv-enabled-nmi-disabled.dat.gz > > Nice revelation! > > KVM doesn't expect host's NMIs to look like this so it doesn't pass them > to the host. What was the watchdog that casually sent NMIs? > (It worked after "nmi_watchdog=0" on the host?) > > (Guest's NMI should have a different result as well. NMI_EXCEPTION is > an expected exit reason for guest's hard exceptions, they are then > differentiated by intr_info and nothing hinted that this was a NMI.) Yes, I disabled host watchdog during runtime. Indeed guest-induced NMI would look different and they had no reasons to be fired at this stage inside guest. I`d suspect a hypervisor hardware misbehavior there but have a very little idea on how APICv behavior (which is completely microcode-dependent and CPU-dependent but decoupled from peripheral hardware) may vary at this point, I am using 1.20140913.1 ucode version from debian if this can matter. Will send trace suggested by Paolo in a next couple of hours. Also it would be awesome to ask hardware folks from Intel who can prove or disprove my abovementioned statement (as I was unable to catch the problem on 2603v2 so far, this hypothesis has some chance to be real). -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
