on 19/09/2013 19:53 Paolo Bonzini said the following: > Il 19/09/2013 16:36, Andriy Gapon ha scritto: >> Not sure how the code ends up at 0x9315 after that. > > Events are dropped, probably corresponding to more emulation.
I've got a trace without dropped events between the last "normal" instruction and the loop (and also including a snippet where the same code is executed without a problem): ... qemu-system-x86-12024 [003] 278157.048876: kvm_emulate_insn: 0:9366:b1 10 (prot32) qemu-system-x86-12024 [003] 278157.048877: kvm_entry: vcpu 0 qemu-system-x86-12024 [003] 278157.048878: kvm_emulate_insn: 0:9368:8e d1 (prot32) qemu-system-x86-12024 [003] 278157.048880: kvm_entry: vcpu 0 qemu-system-x86-12024 [003] 278157.048882: kvm_exit: reason CR_ACCESS rip 0x9312 info 0 0 qemu-system-x86-12024 [003] 278157.048883: kvm_cr: cr_write 0 = 0x10 qemu-system-x86-12024 [003] 278157.048885: kvm_entry: vcpu 0 qemu-system-x86-12024 [003] 278157.048886: kvm_emulate_insn: 0:9315:ea 1a 93 00 00 (real) qemu-system-x86-12024 [003] 278157.048887: kvm_entry: vcpu 0 qemu-system-x86-12024 [003] 278157.048888: kvm_emulate_insn: 0:931a:31 c0 (real) ... ... qemu-system-x86-12024 [003] 278157.048990: kvm_set_irq: gsi 4 level 0 source 0 qemu-system-x86-12024 [003] 278157.048991: kvm_pic_set_irq: chip 0 pin 4 (edge|masked) qemu-system-x86-12024 [003] 278157.048992: kvm_ioapic_set_irq: pin 4 dst 0 vec=0 (Fixed|physical|edge|masked) qemu-system-x86-12024 [003] 278157.049001: kvm_entry: vcpu 0 qemu-system-x86-12024 [003] 278157.049002: kvm_exit: reason IO_INSTRUCTION rip 0x1e675 info 3fd0008 0 qemu-system-x86-12024 [003] 278157.049005: kvm_emulate_insn: a000:1e675:ec (prot32) qemu-system-x86-12024 [003] 278157.049005: kvm_pio: pio_read at 0x3fd size 1 count 1 qemu-system-x86-12024 [003] 278157.049006: kvm_userspace_exit: reason KVM_EXIT_IO (2) qemu-system-x86-12024 [003] 278157.049024: kvm_entry: vcpu 0 qemu-system-x86-12024 [003] 278157.049027: kvm_exit: reason CR_ACCESS rip 0x9312 info 0 0 qemu-system-x86-12024 [003] 278157.049028: kvm_cr: cr_write 0 = 0x10 qemu-system-x86-12024 [003] 278157.049030: kvm_entry: vcpu 0 qemu-system-x86-12024 [003] 278157.049031: kvm_emulate_insn: 0:9315: (real) qemu-system-x86-12024 [003] 278157.049033: kvm_emulate_insn: 0:9315: (real) qemu-system-x86-12024 [003] 278157.049034: kvm_emulate_insn: 0:9315: (real) ... It's strange that no instruction gets reported in those repeating "0:9315: (real)" lines. It's like kvm is somehow losing track of what should be executed and just loops over the same ip without actually doing anything. -- Andriy Gapon