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Wen Xiong 3a96f7f267 scsi: ipr: Enable/disable IRQD_NO_BALANCING during reset 
[ Upstream commit 6ac3484fb1 ]

A dynamic remove/add storage adapter test hits EEH on PowerPC:

  EEH: [c00000000004f75c] __eeh_send_failure_event+0x7c/0x160
  EEH: [c000000000048444] eeh_dev_check_failure.part.0+0x254/0x650
  EEH: [c008000001650678] eeh_readl+0x60/0x90 [ipr]
  EEH: [c00800000166746c] ipr_cancel_op+0x2b8/0x524 [ipr]
  EEH: [c008000001656524] ipr_eh_abort+0x6c/0x130 [ipr]
  EEH: [c000000000ab0d20] scmd_eh_abort_handler+0x140/0x440
  EEH: [c00000000017e558] process_one_work+0x298/0x590
  EEH: [c00000000017eef8] worker_thread+0xa8/0x620
  EEH: [c00000000018be34] kthread+0x124/0x130
  EEH: [c00000000000cd64] ret_from_kernel_thread+0x5c/0x64

A PCIe bus trace reveals that a vector of MSI-X is cleared to 0 by
irqbalance daemon. If we disable irqbalance daemon, we won't see the
issue.

With debug enabled in ipr driver:

  [   44.103071] ipr: Entering __ipr_remove
  [   44.103083] ipr: Entering ipr_initiate_ioa_bringdown
  [   44.103091] ipr: Entering ipr_reset_shutdown_ioa
  [   44.103099] ipr: Leaving ipr_reset_shutdown_ioa
  [   44.103105] ipr: Leaving ipr_initiate_ioa_bringdown
  [   44.149918] ipr: Entering ipr_reset_ucode_download
  [   44.149935] ipr: Entering ipr_reset_alert
  [   44.150032] ipr: Entering ipr_reset_start_timer
  [   44.150038] ipr: Leaving ipr_reset_alert
  [   44.244343] scsi 1:2:3:0: alua: Detached
  [   44.254300] ipr: Entering ipr_reset_start_bist
  [   44.254320] ipr: Entering ipr_reset_start_timer
  [   44.254325] ipr: Leaving ipr_reset_start_bist
  [   44.364329] scsi 1:2:4:0: alua: Detached
  [   45.134341] scsi 1:2:5:0: alua: Detached
  [   45.860949] ipr: Entering ipr_reset_shutdown_ioa
  [   45.860962] ipr: Leaving ipr_reset_shutdown_ioa
  [   45.860966] ipr: Entering ipr_reset_alert
  [   45.861028] ipr: Entering ipr_reset_start_timer
  [   45.861035] ipr: Leaving ipr_reset_alert
  [   45.964302] ipr: Entering ipr_reset_start_bist
  [   45.964309] ipr: Entering ipr_reset_start_timer
  [   45.964313] ipr: Leaving ipr_reset_start_bist
  [   46.264301] ipr: Entering ipr_reset_bist_done
  [   46.264309] ipr: Leaving ipr_reset_bist_done

During adapter reset, ipr device driver blocks config space access but
can't block MMIO access for MSI-X entries.  There is very small window:
irqbalance daemon kicks in during adapter reset before ipr driver calls
pci_restore_state(pdev) to restore MSI-X table.

irqbalance daemon reads back all 0 for that MSI-X vector in
__pci_read_msi_msg().

irqbalance daemon:

  msi_domain_set_affinity()
  ->irq_chip_set_affinity_patent()
  ->xive_irq_set_affinity()
  ->irq_chip_compose_msi_msg()
    ->pseries_msi_compose_msg()
    ->__pci_read_msi_msg(): read all 0 since didn't call pci_restore_state
  ->irq_chip_write_msi_msg()
    -> pci_write_msg_msi(): write 0 to the msix vector entry

When ipr driver calls pci_restore_state(pdev) in
ipr_reset_restore_cfg_space(), the MSI-X vector entry has been cleared
by irqbalance daemon in pci_write_msg_msix().

  pci_restore_state()
  ->__pci_restore_msix_state()

Below is the MSI-X table for ipr adapter after irqbalance daemon kicked
in during adapter reset:

  Dump MSIx table: index=0 address_lo=c800 address_hi=10000000 msg_data=0
  Dump MSIx table: index=1 address_lo=c810 address_hi=10000000 msg_data=0
  Dump MSIx table: index=2 address_lo=c820 address_hi=10000000 msg_data=0
  Dump MSIx table: index=3 address_lo=c830 address_hi=10000000 msg_data=0
  Dump MSIx table: index=4 address_lo=c840 address_hi=10000000 msg_data=0
  Dump MSIx table: index=5 address_lo=c850 address_hi=10000000 msg_data=0
  Dump MSIx table: index=6 address_lo=c860 address_hi=10000000 msg_data=0
  Dump MSIx table: index=7 address_lo=c870 address_hi=10000000 msg_data=0
  Dump MSIx table: index=8 address_lo=0 address_hi=0 msg_data=0
  ---------> Hit EEH since msix vector of index=8 are 0
  Dump MSIx table: index=9 address_lo=c890 address_hi=10000000 msg_data=0
  Dump MSIx table: index=10 address_lo=c8a0 address_hi=10000000 msg_data=0
  Dump MSIx table: index=11 address_lo=c8b0 address_hi=10000000 msg_data=0
  Dump MSIx table: index=12 address_lo=c8c0 address_hi=10000000 msg_data=0
  Dump MSIx table: index=13 address_lo=c8d0 address_hi=10000000 msg_data=0
  Dump MSIx table: index=14 address_lo=c8e0 address_hi=10000000 msg_data=0
  Dump MSIx table: index=15 address_lo=c8f0 address_hi=10000000 msg_data=0

  [   46.264312] ipr: Entering ipr_reset_restore_cfg_space
  [   46.267439] ipr: Entering ipr_fail_all_ops
  [   46.267447] ipr: Leaving ipr_fail_all_ops
  [   46.267451] ipr: Leaving ipr_reset_restore_cfg_space
  [   46.267454] ipr: Entering ipr_ioa_bringdown_done
  [   46.267458] ipr: Leaving ipr_ioa_bringdown_done
  [   46.267467] ipr: Entering ipr_worker_thread
  [   46.267470] ipr: Leaving ipr_worker_thread

IRQ balancing is not required during adapter reset.

Enable "IRQ_NO_BALANCING" flag before starting adapter reset and disable
it after calling pci_restore_state(). The irqbalance daemon is disabled
for this short period of time (~2s).

Co-developed-by: Kyle Mahlkuch <Kyle.Mahlkuch@ibm.com>
Signed-off-by: Kyle Mahlkuch <Kyle.Mahlkuch@ibm.com>
Signed-off-by: Wen Xiong <wenxiong@linux.ibm.com>
Link: https://patch.msgid.link/20251028142427.3969819-2-wenxiong@linux.ibm.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2026-01-17 16:35:18 +01:00
arch alpha: don't reference obsolete termio struct for TC* constants 2026-01-17 16:35:16 +01:00
block block: fix NULL pointer dereference in blk_zone_reset_all_bio_endio() 2026-01-08 10:17:21 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: seqiv - Do not use req->iv after crypto_aead_encrypt 2026-01-08 10:16:43 +01:00
Documentation dt-bindings: PCI: qcom,pcie-sm8550: Add missing required power-domains and resets 2026-01-02 12:57:27 +01:00
drivers scsi: ipr: Enable/disable IRQD_NO_BALANCING during reset 2026-01-17 16:35:18 +01:00
fs smb/client: fix NT_STATUS_NO_DATA_DETECTED value 2026-01-17 16:35:17 +01:00
include drm/atomic-helper: Export and namespace some functions 2026-01-17 16:35:13 +01:00
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring/io-wq: fix incorrect io_wq_for_each_worker() termination logic 2026-01-17 16:35:14 +01:00
ipc namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
kernel PM: hibernate: Fix crash when freeing invalid crypto compressor 2026-01-17 16:35:14 +01:00
lib lib/crypto: aes: Fix missing MMU protection for AES S-box 2026-01-17 16:35:12 +01:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm mm/damon/tests/core-kunit: handle alloc failures on damon_test_split_regions_of() 2026-01-08 10:17:21 +01:00
net libceph: make calc_target() set t->paused, not just clear it 2026-01-17 16:35:15 +01:00
rust rust: maple_tree: rcu_read_lock() in destructor to silence lockdep 2026-01-08 10:17:11 +01:00
samples samples/ftrace: Adjust LoongArch register restore order in direct calls 2026-01-08 10:17:11 +01:00
scripts mcb: Add missing modpost build support 2026-01-08 10:16:47 +01:00
security kernel/kexec: change the prototype of kimage_map_segment() 2026-01-08 10:17:10 +01:00
sound ALSA: hda/realtek: Add support for ASUS UM3406GA 2026-01-17 16:35:17 +01:00
tools selftests/mm: fix thread state check in uffd-unit-tests 2026-01-08 10:17:11 +01:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt KVM: Fix last_boosted_vcpu index assignment bug 2026-01-02 12:57:21 +01:00
.clang-format memblock: drop for_each_free_mem_pfn_range_in_zone_from() 2025-09-14 08:49:03 +03:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore compile_commands.json globally 2025-08-12 15:53:55 -07:00
.mailmap 8 hotfixes. 4 are cc:stable, 7 are against mm/. 2025-11-26 12:38:05 -08:00
.pylintrc tools: docs: parse-headers.py: move it from sphinx dir 2025-08-29 15:54:42 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: mark ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS soc: fixes for 6.18, part 4 2025-11-28 09:57:31 -08:00
Makefile Linux 6.18.5 2026-01-11 15:26:20 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.