Kan Liang 16812c9655 iommu/vt-d: Fix an IOMMU perfmon warning when CPU hotplug ... A warning can be triggered when hotplug CPU 0. $ echo 0 > /sys/devices/system/cpu/cpu0/online ------------[ cut here ]------------ Voluntary context switch within RCU read-side critical section! WARNING: CPU: 0 PID: 19 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0x4f4/0x580 RIP: 0010:rcu_note_context_switch+0x4f4/0x580 Call Trace: <TASK> ? perf_event_update_userpage+0x104/0x150 __schedule+0x8d/0x960 ? perf_event_set_state.part.82+0x11/0x50 schedule+0x44/0xb0 schedule_timeout+0x226/0x310 ? __perf_event_disable+0x64/0x1a0 ? _raw_spin_unlock+0x14/0x30 wait_for_completion+0x94/0x130 __wait_rcu_gp+0x108/0x130 synchronize_rcu+0x67/0x70 ? invoke_rcu_core+0xb0/0xb0 ? __bpf_trace_rcu_stall_warning+0x10/0x10 perf_pmu_migrate_context+0x121/0x370 iommu_pmu_cpu_offline+0x6a/0xa0 ? iommu_pmu_del+0x1e0/0x1e0 cpuhp_invoke_callback+0x129/0x510 cpuhp_thread_fun+0x94/0x150 smpboot_thread_fn+0x183/0x220 ? sort_range+0x20/0x20 kthread+0xe6/0x110 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30 </TASK> ---[ end trace 0000000000000000 ]--- The synchronize_rcu() will be invoked in the perf_pmu_migrate_context(), when migrating a PMU to a new CPU. However, the current for_each_iommu() is within RCU read-side critical section. Two methods were considered to fix the issue. - Use the dmar_global_lock to replace the RCU read lock when going through the drhd list. But it triggers a lockdep warning. - Use the cpuhp_setup_state_multi() to set up a dedicated state for each IOMMU PMU. The lock can be avoided. The latter method is implemented in this patch. Since each IOMMU PMU has a dedicated state, add cpuhp_node and cpu in struct iommu_pmu to track the state. The state can be dynamically allocated now. Remove the CPUHP_AP_PERF_X86_IOMMU_PERF_ONLINE. Fixes: 46284c6ceb ("iommu/vt-d: Support cpumask for IOMMU perfmon") Reported-by: Ammy Yi <ammy.yi@intel.com> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20230328182028.1366416-1-kan.liang@linux.intel.com Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Link: https://lore.kernel.org/r/20230329134721.469447-4-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel <jroedel@suse.de>		2023-03-31 10:06:16 +02:00
..
amd	iommufd for 6.3	2023-02-24 14:34:12 -08:00
arm	ARM: SoC drivers for 6.3	2023-02-27 10:04:49 -08:00
intel	iommu/vt-d: Fix an IOMMU perfmon warning when CPU hotplug	2023-03-31 10:06:16 +02:00
iommufd
apple-dart.c
dma-iommu.c
dma-iommu.h
exynos-iommu.c	iommu/exynos: Fix set_platform_dma_ops() callback	2023-03-28 15:33:50 +02:00
fsl_pamu_domain.c
fsl_pamu_domain.h
fsl_pamu.c
fsl_pamu.h
hyperv-iommu.c
io-pgfault.c
io-pgtable-arm-v7s.c
io-pgtable-arm.c
io-pgtable-arm.h
io-pgtable-dart.c
io-pgtable.c
ioasid.c
iommu-debugfs.c
iommu-sva.c
iommu-sva.h
iommu-sysfs.c
iommu-traces.c
iommu.c	iommufd for 6.3	2023-02-24 14:34:12 -08:00
iova.c
ipmmu-vmsa.c
irq_remapping.c
irq_remapping.h
Kconfig
Makefile
msm_iommu_hw-8xxx.h
msm_iommu.c
msm_iommu.h
mtk_iommu_v1.c
mtk_iommu.c
of_iommu.c
omap-iommu-debug.c
omap-iommu.c
omap-iommu.h
omap-iopgtable.h
rockchip-iommu.c
s390-iommu.c	iommufd for 6.3	2023-02-24 14:34:12 -08:00
sprd-iommu.c
sun50i-iommu.c
tegra-gart.c
tegra-smmu.c
virtio-iommu.c