[PATCHv8 0/5] enable nr_cpus for powerpc

Pingfan Liu piliu at redhat.com
Mon Oct 9 22:30:31 AEDT 2023

Since my last v4 [1], the code has undergone great changes. The paca[]
array has been reorganized and indexed by paca_ptrs[], which
dramatically decreases the memory consumption even if there are many
unpresent cpus in the middle.

However, reordering the logical cpu numbers can further decrease the
size of paca_ptrs[] in the kdump case. So I keep [1-2/5], which
rotate-shifts the cpu's sequence number in the device tree to obtain the
logical cpu id.

Patch [3-5/5] make further efforts to decrease the nr_cpus to be less
than or equal to two.

[1]: https://lore.kernel.org/linuxppc-dev/1520829790-14029-1-git-send-email-kernelfans@gmail.com/
v7 -> v8
  Fix bug when turning on DEBUG macro
  Introducing [PATCHv7 4/5] powerpc/cpu: Skip impossible cpu during iteration on
a core, which avoid access to unpopulated pcpu data.

Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Nicholas Piggin <npiggin at gmail.com>
Cc: Christophe Leroy <christophe.leroy at csgroup.eu>
Cc: Mahesh Salgaonkar <mahesh at us.ibm.com>
Cc: Wen Xiong <wenxiong at us.ibm.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Ming Lei <ming.lei at redhat.com>
Cc: kexec at lists.infradead.org
To: linuxppc-dev at lists.ozlabs.org

Pingfan Liu (5):
  powerpc/setup : Enable boot_cpu_hwid for PPC32
  powerpc/setup: Loosen the mapping between cpu logical id and its seq
    in dt
  powerpc/setup: Handle the case when boot_cpuid greater than nr_cpus
  powerpc/cpu: Skip impossible cpu during iteration on a core
  powerpc/setup: alloc extra paca_ptrs to hold boot_cpuid

 arch/powerpc/include/asm/cputhreads.h    |   6 ++
 arch/powerpc/include/asm/smp.h           |   2 +-
 arch/powerpc/kernel/paca.c               |  10 ++-
 arch/powerpc/kernel/prom.c               |  29 +++---
 arch/powerpc/kernel/setup-common.c       | 108 ++++++++++++++++++-----
 arch/powerpc/kernel/smp.c                |   2 +-
 arch/powerpc/kvm/book3s_hv.c             |   7 +-
 arch/powerpc/platforms/powernv/idle.c    |  32 +++----
 arch/powerpc/platforms/powernv/subcore.c |   5 +-
 9 files changed, 143 insertions(+), 58 deletions(-)


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