The commit: - 2ab2d5794f14 powerpc/kasan: Disable address sanitization in kexec paths was not backported to the 5.15 stable tree upstream (see https://lore.kernel.org/all/2024070819-steering-gag-75e6@gregkh/)
A backport to Jammy tree is needed. Patch sent to KTML: https://lists.ubuntu.com/archives/kernel-team/2025-April/159143.html Marking the bug as "In Progress" ** Description changed: - == Comment: #0 - SEETEENA THOUFEEK <[email protected]> - 2024-08-02 03:11:31 == - +++ This bug was initially created as a clone of Bug #206083 +++ + [ Impact ] - ---Problem Description--- - kexec fails in LPAR when some cpus are disabled - - Contact Information = [email protected] - - Machine Type = na - - ---uname output--- - na - - ---Debugger--- - A debugger is not configured - - ---Steps to Reproduce--- - Summary: - At L1 level, kexec fails if some of the cpus in the machine are disabled. + powerpc/pseries: Fix scv instruction crash with kexec + kexec on pseries disables AIL (reloc_on_exc), required for scv + instruction support, before other CPUs have been shut down. This means + they can execute scv instructions after AIL is disabled, which causes an + interrupt at an unexpected entry location that crashes the kernel. - Distros and kernel versions used: - 1. Distro versions used + Change the kexec sequence to disable AIL after other CPUs have been + brought down. - a. L1 LPAR : + As a refresher, the real-mode scv interrupt vector is 0x17000, and the + fixed-location head code probably couldn't easily deal with implementing + such high addresses so it was just decided not to support that interrupt + at all. - b. L2 : + [ Fix ] + Backport the following commit: + - 21a741eb75f8 powerpc/pseries: Fix scv instruction crash with kexec + from upstream. + + [ Test Plan ] Repro steps: 1. Boot into an L1 lpar 2. Disable some cpus (eg: ppc64_cpu --cores-on=3) - 3. Try to kexec. + 3. Try to kexec. - - This bug is reproducible only when we load the target kernel/initrd and use "kexec -e" as follows: + This bug is reproducible only when we load the target kernel/initrd and + use "kexec -e" as follows: kexec -l --initrd initramfs-$(uname -r).img vmlinuz-$(uname -r) --append="$(cat /proc/cmdline)" kexec -e - - kexec works fine if we do a normal kexec without skipping the shutdown path + kexec works fine if we do a normal kexec without skipping the shutdown + path kexec --initrd initramfs-$(uname -r).img vmlinuz-$(uname -r) --append="$(cat /proc/cmdline)" + [ Where problems could occur ] + + The fix affects the PowerPC pSeries kexec sequence. + A problem with this fix may manifest as system instability + during a kexec transition, unexpected exceptions in early boot of the new kernel, or complete system crashes when attempting to perform a kernel reboot via kexec. + + --- + + == Comment: #0 - SEETEENA THOUFEEK <[email protected]> - 2024-08-02 03:11:31 == + +++ This bug was initially created as a clone of Bug #206083 +++ + + ---Problem Description--- + kexec fails in LPAR when some cpus are disabled + + Contact Information = [email protected] + + Machine Type = na + + ---uname output--- + na + + ---Debugger--- + A debugger is not configured + + ---Steps to Reproduce--- + Summary: + At L1 level, kexec fails if some of the cpus in the machine are disabled. + + Distros and kernel versions used: + 1. Distro versions used + + a. L1 LPAR : + + b. L2 : + + Repro steps: + 1. Boot into an L1 lpar + 2. Disable some cpus (eg: ppc64_cpu --cores-on=3) + 3. Try to kexec. + + This bug is reproducible only when we load the target kernel/initrd and + use "kexec -e" as follows: + + kexec -l --initrd initramfs-$(uname -r).img vmlinuz-$(uname -r) + --append="$(cat /proc/cmdline)" + + kexec -e + + kexec works fine if we do a normal kexec without skipping the shutdown + path + + kexec --initrd initramfs-$(uname -r).img vmlinuz-$(uname -r) + --append="$(cat /proc/cmdline)" Fix is upstream now: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id=21a741eb75f80397e5f7d3739e24d7d75e619011 Thanks, Sourabh Jain please include in Ubuntu - Oops output: - no - + no + Stack trace output: - no - + no + System Dump Info: - The system is not configured to capture a system dump. - - *Additional Instructions for [email protected]: + The system is not configured to capture a system dump. + + *Additional Instructions for [email protected]: -Attach sysctl -a output output to the bug. ** Changed in: linux (Ubuntu Jammy) Status: Triaged => In Progress -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2075575 Title: kexec fails in LPAR when some cpus are disabled To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-power-systems/+bug/2075575/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
