Performing verification for Bionic. I installed the current 4.15.0-162-generic kernel from -updates to a host in segmaas, and brought up my Bionic VM I installed for the reproducer. The Bionic VM has linux-crashdump configured, with nr_cpus configured to 8:
ubuntu@bionic-vm:~$ kdump-config show DUMP_MODE: kdump USE_KDUMP: 1 KDUMP_SYSCTL: kernel.panic_on_oops=1 KDUMP_COREDIR: /var/crash crashkernel addr: 0x /var/lib/kdump/vmlinuz: symbolic link to /boot/vmlinuz-4.15.0-159-generic kdump initrd: /var/lib/kdump/initrd.img: symbolic link to /var/lib/kdump/initrd.img-4.15.0-159-generic current state: ready to kdump kexec command: /sbin/kexec -p --command-line="BOOT_IMAGE=/boot/vmlinuz-4.15.0-159-generic root=UUID=5c23b432-4d00-4a01-8ecd-964803c8e10a ro console=tty1 console=ttyS0 reset_devices systemd.unit=kdump-tools-dump.service nr_cpus=8 irqpoll nousb ata_piix.prefer_ms_hyperv=0 ignore_loglevel nmi_debug=state,regs apic_extnmi=none" --initrd=/var/lib/kdump/initrd.img /var/lib/kdump/vmlinuz I then triggered the crashdump in the VM: $ sudo -s # echo c > /proc/sysrq-trigger On the host, we look at the tail of: $ sudo tail -f /var/log/libvirt/qemu/bionic-vm.log ... KVM internal error. Suberror: 1 emulation failure EAX=0000de8f EBX=00000000 ECX=0000008f EDX=00000600 ESI=00000000 EDI=00000000 EBP=00000000 ESP=0000f90c EIP=0000cdb1 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0 ES =0000 00000000 0000ffff 00009300 CS =f000 000f0000 0000ffff 00009b00 SS =de00 000de000 0000ffff 00009300 DS =de00 000de000 0000ffff 00009300 FS =0000 00000000 0000ffff 00009300 GS =0000 00000000 0000ffff 00009300 LDT=0000 00000000 0000ffff 00008200 TR =0000 00000000 0000ffff 00008b00 GDT= 00000000 0000ffff IDT= 00000000 0000ffff CR0=60000010 CR2=00000000 CR3=32b2a000 CR4=00000000 DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 DR6=00000000ffff0ff0 DR7=0000000000000400 EFER=0000000000000000 Code=66 83 c4 28 66 5b 66 c3 66 56 66 53 66 52 b1 8f 88 c8 e6 70 <e4> 71 66 0f b6 f0 66 89 f2 67 88 54 24 03 88 c8 e6 70 66 31 db 88 d8 e6 71 66 56 66 68 1a $ virsh list Id Name State ---------------------------------------------------- 1 bionic-vm paused Okay, we can reproduce the issue. I then enabled -proposed, and installed the 4.15.0-163-generic kernel: $ uname -rv 4.15.0-163-generic #171-Ubuntu SMP Fri Nov 5 11:55:11 UTC 2021 I started the same VM, verified it has a crashkernel with nr_cpus=8: $ kdump-config show DUMP_MODE: kdump USE_KDUMP: 1 KDUMP_SYSCTL: kernel.panic_on_oops=1 KDUMP_COREDIR: /var/crash crashkernel addr: 0x /var/lib/kdump/vmlinuz: symbolic link to /boot/vmlinuz-4.15.0-159-generic kdump initrd: /var/lib/kdump/initrd.img: symbolic link to /var/lib/kdump/initrd.img-4.15.0-159-generic current state: ready to kdump kexec command: /sbin/kexec -p --command-line="BOOT_IMAGE=/boot/vmlinuz-4.15.0-159-generic root=UUID=5c23b432-4d00-4a01-8ecd-964803c8e10a ro console=tty1 console=ttyS0 reset_devices systemd.unit=kdump-tools-dump.service nr_cpus=8 irqpoll nousb ata_piix.prefer_ms_hyperv=0 ignore_loglevel nmi_debug=state,regs apic_extnmi=none" --initrd=/var/lib/kdump/initrd.img /var/lib/kdump/vmlinuz I then triggered the crashdump: $ sudo -s # echo c > /proc/sysrq-trigger On the host: $ sudo tail -f /var/log/libvirt/qemu/bionic-vm.log ... 2021-11-11T02:41:45.970264Z qemu-system-x86_64: warning: host doesn't support requested feature: CPUID.80000001H:ECX.svm [bit 2] 2021-11-11T02:41:45.971185Z qemu-system-x86_64: warning: host doesn't support requested feature: CPUID.80000001H:ECX.svm [bit 2] $ virsh list Id Name State ---------------------------------------------------- 1 bionic-vm running Checking the VM, the crashdump completed successfully and restarted correctly. $ virsh console bionic-vm ... Copying data : [100.0 %] \ eta: 0s [ 12.034361] kdump-tools[874]: The dumpfile is saved to /var/crash/202111110246/dump-incomplete. [ 12.036787] kdump-tools[874]: makedumpfile Completed. [ 12.038752] kdump-tools[874]: * kdump-tools: saved vmcore in /var/crash/202111110246 [ 12.058489] kdump-tools[874]: * running makedumpfile --dump-dmesg /proc/vmcore /var/crash/202111110246/dmesg.202111110246 [ 12.069700] kdump-tools[874]: The dmesg log is saved to /var/crash/202111110246/dmesg.202111110246. [ 12.072574] kdump-tools[874]: makedumpfile Completed. [ 12.074245] kdump-tools[874]: * kdump-tools: saved dmesg content in /var/crash/202111110246 [ 12.159319] kdump-tools[874]: Thu, 11 Nov 2021 02:46:54 +0000 ... I then did this a further 4 times, each time the crashdump completed succesfully. I then destroyed and started the VM fresh, and kept crashdumping. It worked every time. The 4.15.0-163-generic kernel in -proposed fixes the issue. Happy to mark as verified. ** Tags removed: verification-needed-bionic ** Tags added: verification-done-bionic -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1948862 Title: KVM emulation failure when booting into VM crash kernel with multiple CPUs To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1948862/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
