Gleb Natapov wrote: > 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. Write-back is arch-specific and will never show up directly in vmrun or other generic code. Will update my original patch to make this discussion more concrete. Jan
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