2016-09-14 11:04+0800, Wanpeng Li: > From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx> > > Add -kernel_irqchip=split > ./x86-run x86/eventinj.flat > > qemu-system-x86_64 -enable-kvm -machine kernel_irqchip=split -cpu host > -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc > none -serial stdio -device pci-testdev -kernel x86/eventinj.flat > enabling apic > paging enabled > cr0 = 80010011 > cr3 = 7fff000 > cr4 = 20 > Sending vec 33 and 62 and mask one with TPR > irq1 running > irq1 running > After 33/62 TPR test > FAIL: TPR > irq0 running > irq0 running > > Both irq1 and irq0 are executing twice. > > kvm_entry: vcpu 0 > kvm_exit: reason MSR_WRITE rip 0x401f33 info 0 0 > kvm_apic: apic_write APIC_EOI = 0x0 > kvm_eoi: apicid 0 vector 62 > kvm_msr: msr_write 80b = 0x0 > kvm_entry: vcpu 0 > kvm_exit: reason PENDING_INTERRUPT rip 0x401f35 info 0 0 > kvm_userspace_exit: reason KVM_EXIT_IRQ_WINDOW_OPEN (7) > kvm_inj_virq: irq 62 > kvm_entry: vcpu 0 > kvm_exit: reason IO_INSTRUCTION rip 0x4016ec info 3fd0008 0 > > From the trace we can see there is an interrupt window exit > after the first interrupt EOI(irq 62), and the same irq(62) > is injected duplicately after the interrupt window. > > QEMU does KVM_INTERRUPT(62) ioctl after KVM exits with > KVM_EXIT_IRQ_WINDOW_OPEN, which QEMU requested while the > guest was printing. The printing calls > > serial_update_irq() -> qemu_irq_lower() -> qemu_set_irq() -> > gsi_handler() -> qemu_set_irq() -> pic_irq_request() -> > apic_deliver_pic_intr() -> kvm_handle_interrupt() > > kvm_handle_interrupt() does > > interrupt_request |= CPU_INTERRUPT_HARD > > which later calls cpu_get_pic_interrupt() in kvm_arch_pre_run(), > but that function uses stale information from APIC and injects > 62 again. If we synchronized the APIC, then the test would #GP, > because there would be no injectable interrupt in LAPIC or PIC, > so pic_read_irq() would return 15, thinking it was spurious. > > This patch fix it by don't touch LAPIC if LAPIC is in kernel. > > Suggested-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Suggested-by: Radim Krčmář <rkrcmar@xxxxxxxxxx> > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx> > Cc: Michael S. Tsirkin <mst@xxxxxxxxxx> > Cc: Eduardo Habkost <ehabkost@xxxxxxxxxx> > Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx> > --- Reviewed-by: Radim Krčmář <rkrcmar@xxxxxxxxxx> (The code is horribly tangled, so I might have missed something.) -- 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
