Nikita Leshenko <nikita.leshche...@oracle.com> writes: > The patch looks correct, however I’m confused about why you consider > this to be a bug in the guest rather than a bug in KVM. > > The spec for x2APIC states: > "The support for Directed EOI capability can be detected by means of > bit 24 in the Local APIC Version Register” (Intel’s x2APIC spec, 2.5.1 > Directed EOI) > It seems to me that Windows did the right thing by testing for the > presence of directed EOI feature rather than implying it exists by > testing a version number. KVM did the wrong thing by advertising a > feature it doesn’t support. > > Therefore I think that you should change the comment to something like > “KVM’s in-kernel IOAPIC doesn’t support Directed EOI register, so don’t > advertise this capability in the LAPIC Version Register.” instead of > talking about buggy guests, as it may confuse future readers of this > code. >
Before disabling EOI broadcast guests should check if IOAPIC is of proper version - the fact that you can disable EOI broadcast doesn't automatically mean that you can later do EOI through IOAPIC... Anyway, I got the impression that last time conversation ended up with 'this is a guest bug' conclusion (https://www.spinics.net/lists/kvm/msg148187.html - see Radim's and Ladi's comments) but I'm not insisting - if now we conclude this is not a Windows issue let it be it. But let's just fix it once and for all :-) -- Vitaly
