On 2014-06-30 11:07, Jan Kiszka wrote: > I'm seeing one more issue now: on emulation of "in (%dx),%eax", we leave > to user space several times and check interception also several times Correction: we only leave once for user space. > after returning. We use dx to calculate the port number for the > interception check. But at some point, user space (QEMU) decides to > update that register during vmport access - and now we check the wrong > port in the bitmap (namely port 0). Ideas? > > In general, the same interception checks are done multiple times. Once > after the exit, then again during emulation. Can't we avoid this somehow? > OK, we have different interception stages, but it seems we take multiple ones when we should only take a single: qemu-system-x86-4455 [000] 38083.617545: kvm_exit: reason EXIT_IOIO rip 0x7fc6ead774e4 info 56580241 7fc6ead774e5 qemu-system-x86-4455 [000] 38083.617547: kvm_nested_vmexit: rip 7fc6ead774e4 reason EXIT_IOIO info1 56580241 info2 7fc6ead774e5 int_info 0 int_info_err 0 qemu-system-x86-4455 [000] 38083.617548: bprint: nested_svm_intercept: 5658 4 3c00bacb 0 1 f qemu-system-x86-4455 [000] 38083.617549: bprint: nested_svm_intercept: f0 qemu-system-x86-4455 [000] 38083.617553: kvm_emulate_insn: 0:7fc6ead774e4: ed qemu-system-x86-4455 [000] 38083.617555: bprint: svm_check_intercept: 5658 2 4 43 qemu-system-x86-4455 [000] 38083.617556: bprint: nested_svm_intercept: 5658 4 3c00bacb 0 1 f qemu-system-x86-4455 [000] 38083.617556: bprint: nested_svm_intercept: f0 qemu-system-x86-4455 [000] 38083.617559: kvm_userspace_exit: reason KVM_EXIT_IO (2) qemu-system-x86-4455 [000] 38083.617567: bprint: kvm_arch_vcpu_ioctl_get_regs: 5658 qemu-system-x86-4455 [000] 38083.617598: bprint: kvm_arch_vcpu_ioctl_set_regs: 0 qemu-system-x86-4455 [000] 38083.617628: bprint: svm_check_intercept: 0 2 4 43 qemu-system-x86-4455 [000] 38083.617629: bprint: nested_svm_intercept: 0 4 3c00b000 0 1 f qemu-system-x86-4455 [000] 38083.617630: bprint: nested_svm_intercept: ff qemu-system-x86-4455 [000] 38083.617631: kvm_nested_vmexit_inject: reason EXIT_IOIO info1 241 info2 7fc6ead774e4 int_info 0 int_info_err 0 And you can also see the rdx writing of user space here (rdx is printed in kvm_arch_vcpu_ioctl_*). Jan
Attachment:
signature.asc
Description: OpenPGP digital signature
