kernel/linux.git/arch/s390, branch v6.1.168

s390/barrier: Make array_index_mask_nospec() __always_inline

2026-04-11T12:16:13+00:00

commit c5c0a268b38adffbb2e70e6957017537ff54c157 upstream. Mark array_index_mask_nospec() as __always_inline to guarantee the mitigation is emitted inline regardless of compiler inlining decisions. Fixes: e2dd833389cc ("s390: add optimized array_index_mask_nospec") Cc: stable@kernel.org Reviewed-by: Ilya Leoshkevich Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/syscalls: Add spectre boundary for syscall dispatch table

2026-04-11T12:16:12+00:00

commit 48b8814e25d073dd84daf990a879a820bad2bcbd upstream. The s390 syscall number is directly controlled by userspace, but does not have an array_index_nospec() boundary to prevent access past the syscall function pointer tables. Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Alexander Gordeev Cc: Christian Borntraeger Cc: Sven Schnelle Cc: Arnd Bergmann Fixes: 56e62a737028 ("s390: convert to generic entry") Cc: stable@kernel.org Assisted-by: gkh_clanker_2000 Signed-off-by: Greg Kroah-Hartman Reviewed-by: Vasily Gorbik Link: https://lore.kernel.org/r/2026032404-sterling-swoosh-43e6@gregkh Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/xor: Fix xor_xc_2() inline assembly constraints

2026-03-25T10:03:24+00:00

commit f775276edc0c505dc0f782773796c189f31a1123 upstream. The inline assembly constraints for xor_xc_2() are incorrect. "bytes", "p1", and "p2" are input operands, while all three of them are modified within the inline assembly. Given that the function consists only of this inline assembly it seems unlikely that this may cause any problems, however fix this in any case. Fixes: 2cfc5f9ce7f5 ("s390/xor: optimized xor routing using the XC instruction") Cc: stable@vger.kernel.org Signed-off-by: Heiko Carstens Reviewed-by: Vasily Gorbik Link: https://lore.kernel.org/r/20260302133500.1560531-2-hca@linux.ibm.com Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/pci: Handle futile config accesses of disabled devices directly

2026-03-04T12:20:47+00:00

[ Upstream commit 84d875e69818bed600edccb09be4a64b84a34a54 ] On s390 PCI busses and slots with multiple functions may have holes because PCI functions are passed-through by the hypervisor on a per function basis and some functions may be in standby or reserved. This fact is indicated by returning true from the hypervisor_isolated_pci_functions() helper and triggers common code to scan all possible devfn values. Via pci_scan_single_device() this in turn causes config reads for the device and vendor IDs, even for PCI functions which are in standby and thereofore disabled. So far these futile config reads, as well as potentially writes, which can never succeed were handled by the PCI load/store instructions themselves. This works as the platform just returns an error for a disabled and thus not usable function handle. It does cause spamming of error logs and additional overhead though. Instead check if the used function handle is enabled in zpci_cfg_load() and zpci_cfg_write() and if not enable directly return -ENODEV. Also refactor zpci_cfg_load() and zpci_cfg_store() slightly to accommodate the new logic while meeting modern kernel style guidelines. Cc: stable@vger.kernel.org Fixes: a50297cf8235 ("s390/pci: separate zbus creation from scanning") Signed-off-by: Niklas Schnelle Reviewed-by: Benjamin Block Reviewed-by: Farhan Ali Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin

s390/perf: Disable register readout on sampling events

2026-03-04T12:20:15+00:00

[ Upstream commit b2c04fc1239062b39ddfdd8731ee1a10810dfb74 ] Running commands # ./perf record -IR0,R1 -a sleep 1 extracts and displays register value of general purpose register r1 and r0. However the value displayed of any register is random and does not reflect the register value recorded at the time of the sample interrupt. The sampling device driver on s390 creates a very large buffer for the hardware to store the samples. Only when that large buffer gets full an interrupt is generated and many hundreds of sample entries are processed and copied to the kernel ring buffer and eventually get copied to the perf tool. It is during the copy to the kernel ring buffer that each sample is processed (on s390) and at that time the register values are extracted. This is not the original goal, the register values should be read when the samples are created not when the samples are copied to the kernel ring buffer. Prevent this event from being installed in the first place and return -EOPNOTSUPP. This is already the case for PERF_SAMPLE_REGS_USER. Signed-off-by: Thomas Richter Reviewed-by: Jan Polensky Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin

s390/purgatory: Add -Wno-default-const-init-unsafe to KBUILD_CFLAGS

2026-03-04T12:20:13+00:00

[ Upstream commit b4780fe4ddf04b51127a33d705f4a2e224df00fa ] Add -Wno-default-const-init-unsafe to purgatory KBUILD_CFLAGS, similar to scripts/Makefile.extrawarn, since clang generates warnings for the dummy variable in typecheck(): CC arch/s390/purgatory/purgatory.o arch/s390/include/asm/ptrace.h:221:9: warning: default initialization of an object of type 'typeof (regs->psw)' (aka 'const psw_t') leaves the object uninitialized [-Wdefault-const-init-var-unsafe] 221 | return psw_bits(regs->psw).pstate; | ^ arch/s390/include/asm/ptrace.h:98:2: note: expanded from macro 'psw_bits' 98 | typecheck(psw_t, __psw); \ | ^ include/linux/typecheck.h:11:12: note: expanded from macro 'typecheck' 11 | typeof(x) __dummy2; \ | ^ Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin

s390/smp: Fix fallback CPU detection

2026-01-11T14:18:19+00:00

[ Upstream commit 07a75d08cfa1b883a6e1256666e5f0617ee99231 ] In case SCLP CPU detection does not work a fallback mechanism using SIGP is in place. Since a cleanup this does not work correctly anymore: new CPUs are only considered if their type matches the boot CPU. Before the cleanup the information if a CPU type should be considered was also part of a structure generated by the fallback mechanism and indicated that a CPU type should not be considered when adding CPUs. Since the rework a global SCLP state is used instead. If the global SCLP state indicates that the CPU type should be considered and the fallback mechanism is used, there may be a mismatch with CPU types if CPUs are added. This can lead to a system with only a single CPU even tough there are many more CPUs. Address this by simply copying the boot cpu type into the generated data structure from the fallback mechanism. Reported-by: Alexander Egorenkov Fixes: d08d94306e90 ("s390/smp: cleanup core vs. cpu in the SCLP interface") Reviewed-by: Mete Durlu Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin

s390/pci: Use pci_uevent_ers() in PCI recovery

2025-12-06T21:12:19+00:00

[ Upstream commit dab32f2576a39d5f54f3dbbbc718d92fa5109ce9 ] Issue uevents on s390 during PCI recovery using pci_uevent_ers() as done by EEH and AER PCIe recovery routines. Signed-off-by: Niklas Schnelle Signed-off-by: Bjorn Helgaas Reviewed-by: Lukas Wunner Link: https://patch.msgid.link/20250807-add_err_uevents-v5-2-adf85b0620b0@linux.ibm.com Signed-off-by: Sasha Levin

s390/pci: Avoid deadlock between PCI error recovery and mlx5 crdump

2025-12-06T21:12:14+00:00

[ Upstream commit 0fd20f65df6aa430454a0deed8f43efa91c54835 ] Do not block PCI config accesses through pci_cfg_access_lock() when executing the s390 variant of PCI error recovery: Acquire just device_lock() instead of pci_dev_lock() as powerpc's EEH and generig PCI AER processing do. During error recovery testing a pair of tasks was reported to be hung: mlx5_core 0000:00:00.1: mlx5_health_try_recover:338:(pid 5553): health recovery flow aborted, PCI reads still not working INFO: task kmcheck:72 blocked for more than 122 seconds. Not tainted 5.14.0-570.12.1.bringup7.el9.s390x #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kmcheck state:D stack:0 pid:72 tgid:72 ppid:2 flags:0x00000000 Call Trace: [<000000065256f030>] __schedule+0x2a0/0x590 [<000000065256f356>] schedule+0x36/0xe0 [<000000065256f572>] schedule_preempt_disabled+0x22/0x30 [<0000000652570a94>] __mutex_lock.constprop.0+0x484/0x8a8 [<000003ff800673a4>] mlx5_unload_one+0x34/0x58 [mlx5_core] [<000003ff8006745c>] mlx5_pci_err_detected+0x94/0x140 [mlx5_core] [<0000000652556c5a>] zpci_event_attempt_error_recovery+0xf2/0x398 [<0000000651b9184a>] __zpci_event_error+0x23a/0x2c0 INFO: task kworker/u1664:6:1514 blocked for more than 122 seconds. Not tainted 5.14.0-570.12.1.bringup7.el9.s390x #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u1664:6 state:D stack:0 pid:1514 tgid:1514 ppid:2 flags:0x00000000 Workqueue: mlx5_health0000:00:00.0 mlx5_fw_fatal_reporter_err_work [mlx5_core] Call Trace: [<000000065256f030>] __schedule+0x2a0/0x590 [<000000065256f356>] schedule+0x36/0xe0 [<0000000652172e28>] pci_wait_cfg+0x80/0xe8 [<0000000652172f94>] pci_cfg_access_lock+0x74/0x88 [<000003ff800916b6>] mlx5_vsc_gw_lock+0x36/0x178 [mlx5_core] [<000003ff80098824>] mlx5_crdump_collect+0x34/0x1c8 [mlx5_core] [<000003ff80074b62>] mlx5_fw_fatal_reporter_dump+0x6a/0xe8 [mlx5_core] [<0000000652512242>] devlink_health_do_dump.part.0+0x82/0x168 [<0000000652513212>] devlink_health_report+0x19a/0x230 [<000003ff80075a12>] mlx5_fw_fatal_reporter_err_work+0xba/0x1b0 [mlx5_core] No kernel log of the exact same error with an upstream kernel is available - but the very same deadlock situation can be constructed there, too: - task: kmcheck mlx5_unload_one() tries to acquire devlink lock while the PCI error recovery code has set pdev->block_cfg_access by way of pci_cfg_access_lock() - task: kworker mlx5_crdump_collect() tries to set block_cfg_access through pci_cfg_access_lock() while devlink_health_report() had acquired the devlink lock. A similar deadlock situation can be reproduced by requesting a crdump with > devlink health dump show pci/ reporter fw_fatal while PCI error recovery is executed on the same physical function by mlx5_core's pci_error_handlers. On s390 this can be injected with > zpcictl --reset-fw Tests with this patch failed to reproduce that second deadlock situation, the devlink command is rejected with "kernel answers: Permission denied" - and we get a kernel log message of: mlx5_core 1ed0:00:00.1: mlx5_crdump_collect:50:(pid 254382): crdump: failed to lock vsc gw err -5 because the config read of VSC_SEMAPHORE is rejected by the underlying hardware. Two prior attempts to address this issue have been discussed and ultimately rejected [see link], with the primary argument that s390's implementation of PCI error recovery is imposing restrictions that neither powerpc's EEH nor PCI AER handling need. Tests show that PCI error recovery on s390 is running to completion even without blocking access to PCI config space. Link: https://lore.kernel.org/all/20251007144826.2825134-1-gbayer@linux.ibm.com/ Cc: stable@vger.kernel.org Fixes: 4cdf2f4e24ff ("s390/pci: implement minimal PCI error recovery") Reviewed-by: Niklas Schnelle Signed-off-by: Gerd Bayer Signed-off-by: Heiko Carstens [ Adjust context ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

s390/pci: Restore IRQ unconditionally for the zPCI device

2025-12-06T21:12:13+00:00

[ Upstream commit b45873c3f09153d1ad9b3a7bf9e5c0b0387fd2ea ] Commit c1e18c17bda6 ("s390/pci: add zpci_set_irq()/zpci_clear_irq()"), introduced the zpci_set_irq() and zpci_clear_irq(), to be used while resetting a zPCI device. Commit da995d538d3a ("s390/pci: implement reset_slot for hotplug slot"), mentions zpci_clear_irq() being called in the path for zpci_hot_reset_device(). But that is not the case anymore and these functions are not called outside of this file. Instead zpci_hot_reset_device() relies on zpci_disable_device() also clearing the IRQs, but misses to reset the zdev->irqs_registered flag. However after a CLP disable/enable reset, the device's IRQ are unregistered, but the flag zdev->irq_registered does not get cleared. It creates an inconsistent state and so arch_restore_msi_irqs() doesn't correctly restore the device's IRQ. This becomes a problem when a PCI driver tries to restore the state of the device through pci_restore_state(). Restore IRQ unconditionally for the device and remove the irq_registered flag as its redundant. Fixes: c1e18c17bda6 ("s390/pci: add zpci_set_irq()/zpci_clear_irq()") Cc: stable@vger.kernnel.org Reviewed-by: Niklas Schnelle Reviewed-by: Matthew Rosato Signed-off-by: Farhan Ali Signed-off-by: Heiko Carstens [ adjusted bitfield context ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman