[PATCH v3 0/5] powerpc/xive: remove __GFP_NOFAIL and fix IPI error handling

[Gou Hao]

Changes in v3:
- Split into a separate xive-only series; the drm, test_hmm
  and cxgb4 patches are unchanged since v1 and will no longer be updated here.
- Rework the first patch: instead of simply removing the unreachable
  NULL check, remove __GFP_NOFAIL from the IPI allocation and make
  all xive_ipis access paths NULL-safe (suggested by Andrew Morton [1]
  and Cédric Le Goater).
- Add a patch to defer setting cause_ipi until IPI init succeeds,
  so that smp_muxed_ipi_message_pass() does not call into a
  half-initialized IPI path.
- Add a defensive NULL guard for cause_ipi in
  smp_muxed_ipi_message_pass() as a safety net.

[1] https://lore.kernel.org/all/20260725202632.dcb325658896a470df91cf57@xxxxxxxxxxxxxxxxxxxx/

Changes in v2:
- Remove the now-unused out_free_domain error label in the xive
  patch after deleting the unreachable NULL check goto.
- Fix a use-after-free of xive_ipis: when xive_init_ipis() fails,
  the error path frees xive_ipis but xive_smp_probe() ignores the
  error and proceeds to dereference it in xive_setup_cpu_ipi().
  Propagate the error return through xive_smp_probe() and check
  it in both pnv_smp_probe() and pSeries_smp_probe().

This is a code cleanup series that removes unreachable
NULL checks (and associated error handling) that follow allocations
using __GFP_NOFAIL, which guarantees non-NULL return.

v2: https://lore.kernel.org/all/20260724022851.466017-1-gouhao@xxxxxxxxxxxxx/
v1: https://lore.kernel.org/all/20260723081813.176792-1-gouhao@xxxxxxxxxxxxx/

Gou Hao (5):
  powerpc/xive: make xive IPI allocation NULL-safe
  powerpc/xive: add error return value to xive_smp_probe()
  powerpc/xive: propagate IPI init errors to prevent use-after-free
  powerpc/xive: defer setting cause_ipi until IPI init succeeds
  powerpc/smp: add NULL guard for cause_ipi in
    smp_muxed_ipi_message_pass

 arch/powerpc/include/asm/xive.h      |  4 ++--
 arch/powerpc/kernel/smp.c            |  3 +++
 arch/powerpc/platforms/powernv/smp.c |  8 +++++---
 arch/powerpc/platforms/pseries/smp.c |  8 +++++---
 arch/powerpc/sysdev/xive/common.c    | 28 ++++++++++++++++----------
 5 files changed, 37 insertions(+), 14 deletions(-)

-- 
2.20.1