Description
In the Linux kernel, the following vulnerability has been resolved: powerpc/kexec: Enable SMT before waking offline CPUs If SMT is disabled or a partial SMT state is enabled, when a new kernel image is loaded for kexec, on reboot the following warning is observed: kexec: Waking offline cpu 228. WARNING: CPU: 0 PID: 9062 at arch/powerpc/kexec/core_64.c:223 kexec_prepare_cpus+0x1b0/0x1bc [snip] NIP kexec_prepare_cpus+0x1b0/0x1bc LR kexec_prepare_cpus+0x1a0/0x1bc Call Trace: kexec_prepare_cpus+0x1a0/0x1bc (unreliable) default_machine_kexec+0x160/0x19c machine_kexec+0x80/0x88 kernel_kexec+0xd0/0x118 __do_sys_reboot+0x210/0x2c4 system_call_exception+0x124/0x320 system_call_vectored_common+0x15c/0x2ec This occurs as add_cpu() fails due to cpu_bootable() returning false for CPUs that fail the cpu_smt_thread_allowed() check or non primary threads if SMT is disabled. Fix the issue by enabling SMT and resetting the number of SMT threads to the number of threads per core, before attempting to wake up all present CPUs.
Product status
482fa21635c8832db022cd2d649db26b8e6170ac (git) before 7cccd82a0e4aad192fd74fc60e61ed9aed5857a3
38253464bc821d6de6bba81bb1412ebb36f6cbd1 (git) before d790ef0c4819424ee0c2f448c0a8154c5ca369d1
38253464bc821d6de6bba81bb1412ebb36f6cbd1 (git) before f0c0a681ffb77b8c5290c88c02d968199663939b
38253464bc821d6de6bba81bb1412ebb36f6cbd1 (git) before 0d5c9e901ad40bd39b38e119c0454b52d7663930
38253464bc821d6de6bba81bb1412ebb36f6cbd1 (git) before c2296a1e42418556efbeb5636c4fa6aa6106713a
15141adf85b14a7cff7abba1cb983f0bf17e3b36 (git)
6.6
Any version before 6.6
6.1.160 (semver)
6.6.120 (semver)
6.12.64 (semver)
6.18.3 (semver)
6.19 (original_commit_for_fix)
References
git.kernel.org/...c/7cccd82a0e4aad192fd74fc60e61ed9aed5857a3
git.kernel.org/...c/d790ef0c4819424ee0c2f448c0a8154c5ca369d1
git.kernel.org/...c/f0c0a681ffb77b8c5290c88c02d968199663939b
git.kernel.org/...c/0d5c9e901ad40bd39b38e119c0454b52d7663930
git.kernel.org/...c/c2296a1e42418556efbeb5636c4fa6aa6106713a