On Thu, Jan 31, 2013 at 11:44:43AM -0200, Marcelo Tosatti wrote: > On Thu, Jan 31, 2013 at 03:38:37PM +0200, Gleb Natapov wrote: > > On Thu, Jan 31, 2013 at 11:32:45AM -0200, Marcelo Tosatti wrote: > > > On Thu, Jan 31, 2013 at 11:43:48AM +0200, Gleb Natapov wrote: > > > > On Wed, Jan 30, 2013 at 09:03:11PM -0200, Marcelo Tosatti wrote: > > > > > Posted interrupt patch: > > > > > 2) Must move IN_GUEST_MODE assignment after local_irq_disable, in > > > > > vcpu_enter_guest function. Otherwise: > > > > > > > > > > cpu0 vcpu1<->cpu1 > > > > > > > > > > vcpu->mode = IN_GUEST_MODE > > > > > > > > > > if IN_GUEST_MODE == true > > > > > send IPI > > > > > local_irq_disable > > > > > > > > > > PIR not transferred to VIRR, misses interrupt. > > > > > > > > > cpu0 will set KVM_REQ_EVENT, so vmentry will be aborted after > > > > local_irq_disable() by ->requests check. > > > > > > Yes, but you don't want KVM_REQ_EVENT+kick. It defeats the purpose > > > of posted interrupts. You want > > > > > > if vcpu in guest mode > > > send posted interrupt IPI > > > else > > > KVM_REQ_EVENT+kick > > > > > I am thinking: > > > > set KVM_REQ_EVENT > > if pi is enabled > > send posted interrupt IPI > > else > > kick > > KVM_REQ_EVENT must be after sending posted interrupt IPI. Otherwise on > the vcpu entry side > > test_and_clear(KVM_REQ_EVENT) { > No bits set in PIR > } > It should be after updating PIR, but before sending posted interrupt IPI. Otherwise: cpu0 cpu1/vcpu KVM_REQ_EVENT is not set set pir send IPI irq_disable() ->request is empty. set KVM_REQ_EVENT That's the same sequence as with IRR update, KVM_REQ_EVENT and kick today. > What about item 4 below? > That's for Yang to answer :) > > > > > 3) Must check outstanding PIR notification bit unconditionally on > > > > > every VM-entry, because: > > > > > > > > > > 1. local_irq_disable > > > > > 2. vcpu->mode = IN_GUEST_MODE > > > > > 3. vmenter > > > > > 4. vmexit > > > > > 5. vcpu->mode = OUTSIDE_GUEST_MODE > > > > > > > > > > If PIR-IPI-interrupt is sent between an event which triggers VM-exit > > > > > (for example, an external interrupt due to a device), and step 5 > > > > > (assignment of vcpu->mode), the PIR->VIRR transfer before vmentry must > > > > > be made. > > > > Not sure I understand, but I think KVM_REQ_EVENT will cover that too. > > > > > > See above. > > > > > > > > > > > > > 4) Today, an interrupt notification is cached on IRR until its delivered - further > > > > > interrupt injection is not generating further interrupt notification > > > > > bits. With PIR, behaviour changes: Its possible to have one bit in PIR and another > > > > > on IRR APIC page (if timing is right). Is this harmless? Why? > > > > > > > > > > > > > > > > > > -- > > > > Gleb. > > > > -- > > Gleb. -- 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