On 2013-03-17 09:47, Gleb Natapov wrote: > On Sat, Mar 16, 2013 at 09:49:07PM +0100, Jan Kiszka wrote: >> From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> >> >> If the guest didn't take the last APIC timer interrupt yet and generates >> another one on top, e.g. via periodic mode, we do not block the VCPU >> even if the guest state is halted. The reason is that >> apic_has_pending_timer continues to return a non-zero value. >> >> Fix this busy loop by taking the IRR content for the LVT vector in >> apic_has_pending_timer into account. >> > Just drop coalescing tacking for lapic interrupt. After posted interrupt > will be merged __apic_accept_irq() will not longer return coalescing > information, so the code will be dead anyway. If I understood the follow-up discussion correctly, we aren't dropping de-coalescing support yet. So how to proceed with this fix here? Jan > >> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> >> --- >> >> Not a critical issue, we are looping fully interruptible, but it's ugly >> to do so IMHO. >> >> arch/x86/kvm/lapic.c | 4 +++- >> 1 files changed, 3 insertions(+), 1 deletions(-) >> >> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c >> index a8e9369..658abf5 100644 >> --- a/arch/x86/kvm/lapic.c >> +++ b/arch/x86/kvm/lapic.c >> @@ -1473,7 +1473,9 @@ int apic_has_pending_timer(struct kvm_vcpu *vcpu) >> struct kvm_lapic *apic = vcpu->arch.apic; >> >> if (kvm_vcpu_has_lapic(vcpu) && apic_enabled(apic) && >> - apic_lvt_enabled(apic, APIC_LVTT)) >> + apic_lvt_enabled(apic, APIC_LVTT) && >> + !apic_test_vector(apic_lvt_vector(apic, APIC_LVTT), >> + apic->regs + APIC_IRR)) >> return atomic_read(&apic->lapic_timer.pending); >> >> return 0; >> -- >> 1.7.3.4 > > -- > Gleb.
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