On Wed, Dec 09, 2009 at 10:01:36PM +0100, Jan Kiszka wrote: > Gleb Natapov wrote: > > On Wed, Dec 09, 2009 at 09:09:54PM +0100, Jan Kiszka wrote: > >> Gleb Natapov wrote: > >>> On Wed, Dec 09, 2009 at 07:23:38PM +0100, Jan Kiszka wrote: > >>>> Marcelo Tosatti wrote: > >>>>> Otherwise a zero apic base is loaded into KVM, which results > >>>>> in interrupts being lost until a proper apic base with enabled > >>>>> bit set is loaded. > >>>>> > >>>>> Fixes WinXP migration in qemu-kvm origin/next. > >>>>> > >>>>> Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx> > >>>>> > >>>>> diff --git a/hw/apic.c b/hw/apic.c > >>>>> index 627ff98..45a4d2b 100644 > >>>>> --- a/hw/apic.c > >>>>> +++ b/hw/apic.c > >>>>> @@ -1131,6 +1131,11 @@ int apic_init(CPUState *env) > >>>>> vmstate_register(s->idx, &vmstate_apic, s); > >>>>> qemu_register_reset(apic_reset, s); > >>>>> > >>>>> + /* apic_reset must be called before the vcpu threads are initialized and load > >>>>> + * registers, in qemu-kvm. > >>>>> + */ > >>>>> + apic_reset(s); > >>>>> + > >>>>> local_apics[s->idx] = s; > >>>>> return 0; > >>>>> } > >>>> Heals the issue I saw with Win2003 Server as well. > >>>> > >>>> Looks all a bit messy though. Hope we can establish a more regular and > >>>> less fragile model on the midterm. I wonder if it wouldn't be better to > >>>> do write-back of the local APIC state along with the register state on > >>>> vmrun (and only there!). The same would apply to things like mpstate, > >>> Write back of mp state there is a bug and introduce races. Do write back > >>> of the whole APIC state there looks like a recipe for disaster. > >> Please read the full suggestion: We will only write-back if we were > >> going through a reset or vmload before. That removes the ugly kvm hooks > >> from generic code and ensures proper ordering /wrt other write-backs. > >> IMHO, anything else will continue to cause headache like the above to us. > >> > > We can't postpone APIC loading till vmrun. This will race with > > devices/other vcpus sending interrupts to the vcpu. APIC state of all > > vcpus should be up-to-date _before_ any vcpu or main loop starts > > running. > > Simple to solve, just add another write-back point: vm_start. > So what's the point to have write-back for APIC in vmrun? It is always wrong to do it there. -- Gleb. -- 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
