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Paolo Bonzini bf2c3138ae Merge tag 'kvm-x86-pmu-6.20' of https://github.com/kvm-x86/linux into HEAD 
KVM mediated PMU support for 6.20

Add support for mediated PMUs, where KVM gives the guest full ownership of PMU
hardware (contexted switched around the fastpath run loop) and allows direct
access to data MSRs and PMCs (restricted by the vPMU model), but intercepts
access to control registers, e.g. to enforce event filtering and to prevent the
guest from profiling sensitive host state.

To keep overall complexity reasonable, mediated PMU usage is all or nothing
for a given instance of KVM (controlled via module param).  The Mediated PMU
is disabled default, partly to maintain backwards compatilibity for existing
setup, partly because there are tradeoffs when running with a mediated PMU that
may be non-starters for some use cases, e.g. the host loses the ability to
profile guests with mediated PMUs, the fastpath run loop is also a blind spot,
entry/exit transitions are more expensive, etc.

Versus the emulated PMU, where KVM is "just another perf user", the mediated
PMU delivers more accurate profiling and monitoring (no risk of contention and
thus dropped events), with significantly less overhead (fewer exits and faster
emulation/programming of event selectors) E.g. when running Specint-2017 on
a single-socket Sapphire Rapids with 56 cores and no-SMT, and using perf from
within the guest:

  Perf command:
  a. basic-sampling: perf record -F 1000 -e 6-instructions  -a --overwrite
  b. multiplex-sampling: perf record -F 1000 -e 10-instructions -a --overwrite

  Guest performance overhead:
  ---------------------------------------------------------------------------
  | Test case          | emulated vPMU | all passthrough | passthrough with |
  |                    |               |                 | event filters    |
  ---------------------------------------------------------------------------
  | basic-sampling     |   33.62%      |    4.24%        |   6.21%          |
  ---------------------------------------------------------------------------
  | multiplex-sampling |   79.32%      |    7.34%        |   10.45%         |
  ---------------------------------------------------------------------------
 		2026-02-11 12:45:40 -05:00
..
bpf bpf: Reject BPF_MAP_TYPE_INSN_ARRAY in check_reg_const_str() 2026-01-07 19:03:46 -08:00
cgroup cgroup/dmem: avoid pool UAF 2026-02-02 06:04:13 -10:00
configs hung_task: panic when there are more than N hung tasks at the same time 2025-11-12 10:00:14 -08:00
debug kdb: Adapt kdb_msg_write to work with NBCON consoles 2025-10-24 12:56:20 +02:00
dma dma: contiguous: Check return value of dma_contiguous_reserve_area() 2026-02-02 09:20:32 +01:00
entry rseq: Switch to TIF_RSEQ if supported 2025-11-04 08:35:37 +01:00
events Merge tag 'kvm-x86-pmu-6.20' of https://github.com/kvm-x86/linux into HEAD 2026-02-11 12:45:40 -05:00
futex Futex changes for v6.19: 2025-12-10 17:21:30 +09:00
gcov gcov: add support for GCC 15 2025-11-09 21:19:44 -08:00
irq treewide: Update email address 2026-01-11 06:09:11 -10:00
kcsan Kernel Concurrency Sanitizer (KCSAN) updates for v6.18 2025-10-02 08:31:44 -07:00
livepatch livepatch: Fix having __klp_objects relics in non-livepatch modules 2026-02-05 08:00:44 -08:00
liveupdate liveupdate: luo_file: do not clear serialized_data on unfreeze 2026-02-02 18:43:55 -08:00
locking RCU pull request for v6.19 2025-12-03 12:18:07 -08:00
module kernel: modules: Add SPDX license identifier to kmod.c 2026-01-15 16:58:28 -08:00
power Merge branch 'pm-em' 2026-01-16 16:16:24 +01:00
printk printk fixup for 6.19 rc6 2026-01-16 09:46:59 -08:00
rcu RCU pull request for v6.19 2025-12-03 12:18:07 -08:00
sched Miscellaneous MMCID fixes to address bugs and 2026-02-07 09:10:42 -08:00
time clocksource: Reduce watchdog readout delay limit to prevent false positives 2026-01-21 11:33:11 +01:00
trace tracing: Fix ftrace event field alignments 2026-02-05 09:47:11 -05:00
unwind unwind_user/fp: Use dummies instead of ifdef 2025-12-17 13:31:07 +01:00
.gitignore kheaders: rebuild kheaders_data.tar.xz when a file is modified within a minute 2025-06-24 20:30:37 +09:00
Kconfig.freezer
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Kconfig.hz kernel: Fix "select" wording on HZ_250 description 2025-02-21 09:20:30 +01:00
Kconfig.kexec liveupdate: kho: move to kernel/liveupdate 2025-11-27 14:24:33 -08:00
Kconfig.locks
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Kconfig.preempt softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT 2025-09-17 16:25:41 +02:00
Makefile liveupdate: kho: move to kernel/liveupdate 2025-11-27 14:24:33 -08:00
acct.c act: use credential guards in acct_write_process() 2025-11-04 12:36:49 +01:00
async.c
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audit.c audit: fix skb leak when audit rate limit is exceeded 2025-09-10 19:55:00 -04:00
audit.h audit: fix comment misindentation in audit.h 2025-10-22 19:28:06 -04:00
audit_fsnotify.c VFS/audit: introduce kern_path_parent() for audit 2025-09-23 12:37:35 +02:00
audit_tree.c mount-related stuff for this cycle 2025-10-03 10:19:44 -07:00
audit_watch.c VFS/audit: introduce kern_path_parent() for audit 2025-09-23 12:37:35 +02:00
auditfilter.c audit: Use kzalloc() instead of kmalloc()/memset() in audit_krule_to_data() 2025-11-07 16:38:34 -05:00
auditsc.c audit: merge loops in __audit_inode_child() 2025-11-07 16:50:42 -05:00
backtracetest.c
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bounds.c x86/asm: Remove ANNOTATE_DATA_SPECIAL usage 2025-12-03 16:53:19 +01:00
capability.c capability: Remove unused has_capability 2025-03-07 22:03:09 -06:00
cfi.c cfi: Move BPF CFI types and helpers to generic code 2025-07-31 18:23:53 -07:00
compat.c
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configs.c
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context_tracking.c context_tracking: Make RCU watch ct_kernel_exit_state() warning 2025-03-04 18:44:29 -08:00
cpu.c cpu: Make atomic hotplug callbacks run with interrupts disabled on UP 2025-12-10 15:49:11 +09:00
cpu_pm.c syscore: Pass context data to callbacks 2025-11-14 10:01:52 +01:00
crash_core.c crash: fix crashkernel resource shrink 2025-11-15 10:52:01 -08:00
crash_core_test.c crash: add KUnit tests for crash_exclude_mem_range 2025-09-13 17:32:55 -07:00
crash_dump_dm_crypt.c crash_dump: retrieve dm crypt keys in kdump kernel 2025-05-21 10:48:21 -07:00
crash_reserve.c crash: let architecture decide crash memory export to iomem_resource 2025-11-12 10:00:15 -08:00
cred.c kernel-6.19-rc1.cred 2025-12-01 13:45:41 -08:00
delayacct.c delayacct: remove redundant code and adjust indentation 2025-05-27 19:40:33 -07:00
dma.c
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elfcorehdr.c
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exec_domain.c
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exit.c Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
exit.h
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extable.c
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fail_function.c
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fork.c Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
freezer.c freezer: Clarify that only cgroup1 freezer uses PM freezer 2025-10-30 20:10:27 +01:00
gen_kheaders.sh kheaders: make it possible to override TAR 2025-08-06 10:23:36 +09:00
groups.c
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hung_task.c hung_task: add hung_task_sys_info sysctl to dump sys info on task-hung 2025-11-20 14:03:43 -08:00
iomem.c mm/memremap: Pass down MEMREMAP_* flags to arch_memremap_wb() 2025-02-21 15:05:38 +01:00
irq_work.c
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jump_label.c jump_label: Use RCU in all users of __module_text_address(). 2025-03-10 11:54:46 +01:00
kallsyms.c kallsyms: Fix wrong "big" kernel symbol type read from procfs 2025-11-24 16:56:24 +01:00
kallsyms_internal.h
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kallsyms_selftest.c kallsyms: use kmalloc_array() instead of kmalloc() 2025-09-28 11:36:14 -07:00
kallsyms_selftest.h
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kcmp.c kcmp: improve performance adding an unlikely hint to task comparisons 2025-02-21 10:25:33 +01:00
kcov.c kcov: use write memory barrier after memcpy() in kcov_move_area() 2025-09-13 17:32:44 -07:00
kexec.c kexec: enable CMA based contiguous allocation 2025-08-02 12:01:38 -07:00
kexec_core.c kernel/kexec: fix IMA when allocation happens in CMA area 2025-12-23 11:23:14 -08:00
kexec_elf.c kexec: initialize ELF lowest address to ULONG_MAX 2025-03-16 22:30:47 -07:00
kexec_file.c x86/kexec: carry forward the boot DTB on kexec 2025-09-13 17:32:43 -07:00
kexec_internal.h kexec: enable CMA based contiguous allocation 2025-08-02 12:01:38 -07:00
kheaders.c
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kprobes.c kprobes: Add missing kerneldoc for __get_insn_slot 2025-07-15 18:45:34 +09:00
kstack_erase.c sysctl: remove __user qualifier from stack_erasing_sysctl buffer argument 2025-11-27 15:44:53 +01:00
ksyms_common.c
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ksysfs.c kexec: move sysfs entries to /sys/kernel/kexec 2025-11-27 14:24:42 -08:00
kthread.c kthread: Warn if mm_struct lacks user_ns in kthread_use_mm() 2025-12-24 21:32:58 +01:00
latencytop.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
module_signature.c
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notifier.c
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nscommon.c ns: rename is_initial_namespace() 2025-11-11 10:01:31 +01:00
nsproxy.c nsproxy: fix free_nsproxy() and simplify create_new_namespaces() 2025-11-14 13:10:38 +01:00
nstree.c nstree: fix kernel-doc comments for internal functions 2025-11-14 13:10:38 +01:00
padata.c padata: remove __padata_list_init() 2025-11-14 18:15:49 +08:00
panic.c panic: only warn about deprecated panic_print on write access 2026-01-19 12:30:01 -08:00
params.c params: Replace deprecated strcpy() with strscpy() and memcpy() 2025-08-16 21:47:25 +02:00
pid.c ns: drop custom reference count initialization for initial namespaces 2025-11-11 10:01:32 +01:00
pid_namespace.c pid: rely on common reference count behavior 2025-11-11 10:01:32 +01:00
pid_sysctl.h treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
profile.c
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ptrace.c rseq: Introduce struct rseq_data 2025-11-04 08:30:50 +01:00
range.c
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reboot.c - The 7 patch series "powerpc/crash: use generic crashkernel 2025-04-01 10:06:52 -07:00
regset.c
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relay.c relay: update relay to use mmap_prepare 2025-11-16 17:28:11 -08:00
resource.c Reinstate "resource: avoid unnecessary lookups in find_next_iomem_res()" 2025-11-27 14:24:45 -08:00
resource_kunit.c
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rseq.c rseq: Switch to fast path processing on exit to user 2025-11-04 08:34:39 +01:00
scftorture.c
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scs.c scs: fix a wrong parameter in __scs_magic 2025-11-12 10:00:13 -08:00
seccomp.c Performance events updates for v6.18: 2025-09-30 11:11:21 -07:00
signal.c signal: Move MMCID exit out of sighand lock 2025-11-25 19:45:40 +01:00
smp.c smp: Introduce a helper function to check for pending IPIs 2025-11-19 18:06:50 +01:00
smpboot.c sched/smp: Use the SMP version of idle_thread_set_boot_cpu() 2025-06-13 08:47:20 +02:00
smpboot.h
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softirq.c softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT 2025-09-17 16:25:41 +02:00
stacktrace.c
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static_call.c
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static_call_inline.c Modules changes for 6.15-rc1 2025-03-30 15:44:36 -07:00
stop_machine.c sched/core: Fix migrate_swap() vs. hotplug 2025-07-01 15:02:03 +02:00
sys.c Patch series in this pull request: 2025-10-02 18:44:54 -07:00
sys_ni.c uprobes/x86: Add uprobe syscall to speed up uprobe 2025-08-21 20:09:20 +02:00
sysctl-test.c sysctl: move u8 register test to lib/test_sysctl.c 2025-04-14 14:13:41 +02:00
sysctl.c sysctl: Wrap do_proc_douintvec with the public function proc_douintvec_conv 2025-11-27 15:45:38 +01:00
task_work.c task_work: Fix NMI race condition 2025-10-29 10:29:54 +01:00
taskstats.c
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torture.c torture: Delay CPU-hotplug operations until boot completes 2025-08-14 15:26:30 -07:00
tracepoint.c tracepoint: Print the function symbol when tracepoint_debug is set 2025-03-21 15:30:10 -04:00
tsacct.c pid: change bacct_add_tsk() to use task_ppid_nr_ns() 2025-08-19 13:38:20 +02:00
ucount.c ucount: use atomic_long_try_cmpxchg() in atomic_long_inc_below() 2025-08-02 12:01:38 -07:00
uid16.c
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uid16.h
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umh.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
up.c
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user-return-notifier.c
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user.c ns: drop custom reference count initialization for initial namespaces 2025-11-11 10:01:32 +01:00
user_namespace.c ns: move ns type into struct ns_common 2025-09-25 09:23:54 +02:00
utsname.c namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
utsname_sysctl.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
vhost_task.c vhost: Take a reference on the task in struct vhost_task. 2025-09-21 17:44:20 -04:00
vmcore_info.c vmcoreinfo: make hwerr_data visible for debugging 2026-01-26 19:03:49 -08:00
watch_queue.c watch_queue: Use local kmap in post_one_notification() 2025-11-19 12:17:28 +01:00
watchdog.c powerpc/watchdog: add support for hardlockup_sys_info sysctl 2026-01-14 22:16:22 -08:00
watchdog_buddy.c watchdog: fix opencoded cpumask_next_wrap() in watchdog_next_cpu() 2025-07-31 11:28:03 -04:00
watchdog_perf.c watchdog: skip checks when panic is in progress 2025-09-13 17:32:53 -07:00
workqueue.c workqueue: Don't rely on wq->rescuer to stop rescuer 2025-11-21 09:45:36 -10:00
workqueue_internal.h
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