forked from Minki/linux
4145f35864
Certain HMI's such as malfunction error propagate through all threads/core on the system. If a thread was offline prior to us crashing the system and jumping to the kdump kernel, bad things happen when it wakes up due to an HMI in the kdump kernel. There are several possible ways to solve this problem 1. Put the offline cores in a state such that they are not woken up for machine check and HMI errors. This does not work, since we might need to wake up offline threads to handle TB errors 2. Ignore HMI errors, setup HMEER to mask HMI errors, but this still leads the window open for any MCEs and masking them for the duration of the dump might be a concern 3. Wake up offline CPUs, as in send them to crash_ipi_callback (not wake them up as in mark them online as seen by the hotplug). kexec does a wake_online_cpus() call, this patch does something similar, but instead sends an IPI and forces them to crash_ipi_callback() This patch takes approach #3. Care is taken to enable this only for powenv platforms via crash_wake_offline (a global value set at setup time). The crash code sends out IPI's to all CPU's which then move to crash_ipi_callback and kexec_smp_wait(). Signed-off-by: Balbir Singh <bsingharora@gmail.com> Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> |
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