On 2012-06-28 11:11, Peter Lieven wrote: > On 27.06.2012 18:54, Jan Kiszka wrote: >> On 2012-06-27 17:39, Peter Lieven wrote: >>> Hi all, >>> >>> i debugged this further and found out that kvm-kmod-3.0 is working with >>> qemu-kvm-1.0.1 while kvm-kmod-3.3 and kvm-kmod-3.4 are not. What is >>> working as well is kvm-kmod-3.4 with an old userspace (qemu-kvm-0.13.0). >>> Has anyone a clue which new KVM feature could cause this if a vcpu is in >>> an infinite loop? >> Before accusing kvm-kmod ;), can you check if the effect is visible with >> an original Linux 3.3.x or 3.4.x kernel as well? > sorry, i should have been more specific. maybe I also misunderstood sth. > I was believing that kvm-kmod-3.0 is basically what is in vanialla kernel > 3.0. If I use the ubuntu kernel from ubuntu oneiric (3.0.0) it works, if > I use > a self-compiled kvm-kmod-3.3/3.4 with that kernel it doesn't. > however, maybe we don't have to dig to deep - see below. kvm-kmod wraps and patches things to make the kvm code from 3.3/3.4 working on an older kernel. This step may introduce bugs of its own. Therefore my suggestion to use a "real" 3.x kernel to exclude that risk first of all. >> Then, bisection the change in qemu-kvm that apparently resolved the >> issue would be interesting. >> >> If we have to dig deeper, tracing [1] the lockup would likely be helpful >> (all events of the qemu process, not just KVM related ones: trace-cmd >> record -e all qemu-system-x86_64 ...). > that here is bascially whats going on: > > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_mmio: mmio read > len 3 gpa 0xa0000 val 0x10ff > qemu-kvm-1.0-2506 [010] 60996.908000: vcpu_match_mmio: gva > 0xa0000 gpa 0xa0000 Read GPA > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_mmio: mmio > unsatisfied-read len 1 gpa 0xa0000 val 0x0 > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_userspace_exit: reason > KVM_EXIT_MMIO (6) > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_mmio: mmio > read len 3 gpa 0xa0000 val 0x10ff > qemu-kvm-1.0-2506 [010] 60996.908000: vcpu_match_mmio: gva > 0xa0000 gpa 0xa0000 Read GPA > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_mmio: mmio > unsatisfied-read len 1 gpa 0xa0000 val 0x0 > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_userspace_exit: reason > KVM_EXIT_MMIO (6) > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_mmio: mmio > read len 3 gpa 0xa0000 val 0x10ff > qemu-kvm-1.0-2506 [010] 60996.908000: vcpu_match_mmio: gva > 0xa0000 gpa 0xa0000 Read GPA > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_mmio: mmio > unsatisfied-read len 1 gpa 0xa0000 val 0x0 > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_userspace_exit: reason > KVM_EXIT_MMIO (6) > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_mmio: mmio > read len 3 gpa 0xa0000 val 0x10ff > qemu-kvm-1.0-2506 [010] 60996.908000: vcpu_match_mmio: gva > 0xa0000 gpa 0xa0000 Read GPA > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_mmio: mmio > unsatisfied-read len 1 gpa 0xa0000 val 0x0 > qemu-kvm-1.0-2506 [010] 60996.908000: kvm_userspace_exit: reason > KVM_EXIT_MMIO (6) > > its doing that forever. this is tracing the kvm module. doing the > qemu-system-x86_64 trace is a bit compilcated, but > maybe this is already sufficient. otherwise i will of course gather this > info as well. That's only tracing KVM event, and it's tracing when things went wrong already. We may need a full trace (-e all) specifically for the period when this pattern above started. However, let's focus on bisecting at kernel and qemu-kvm level first. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- 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
