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Maxim Levitsky e4a454ced7 KVM: add kvm_lock_all_vcpus and kvm_trylock_all_vcpus
In a few cases, usually in the initialization code, KVM locks all vCPUs
of a VM to ensure that userspace doesn't do funny things while KVM performs
an operation that affects the whole VM.

Until now, all these operations were implemented using custom code,
and all of them share the same problem:

Lockdep can't cope with simultaneous locking of a large number of locks of
the same class.

However if these locks are taken while another lock is already held,
which is luckily the case, it is possible to take advantage of little known
_nest_lock feature of lockdep which allows in this case to have an
unlimited number of locks of same class to be taken.

To implement this, create two functions:
kvm_lock_all_vcpus() and kvm_trylock_all_vcpus()

Both functions are needed because some code that will be replaced in
the subsequent patches, uses mutex_trylock, instead of regular mutex_lock.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Message-ID: <20250512180407.659015-4-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-05-27 12:16:41 -04:00
arch x86/tdx: mark tdh_vp_enter() as __flatten 2025-05-26 16:45:07 -04:00
block SCSI fixes on 20250516 2025-05-16 10:28:22 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: scompress - increment scomp_scratch_users when already allocated 2025-04-25 10:33:30 +08:00
Documentation KVM/riscv changes for 6.16 2025-05-26 16:27:00 -04:00
drivers dmaengine fixes for v6.15 2025-05-17 12:53:39 -07:00
fs two smb3 client fixes 2025-05-16 18:02:41 -07:00
include KVM: add kvm_lock_all_vcpus and kvm_trylock_all_vcpus 2025-05-27 12:16:41 -04:00
init init: remove unused CONFIG_CC_CAN_LINK_STATIC 2025-05-12 15:03:46 +09:00
io_uring io_uring/fdinfo: grab ctx->uring_lock around io_uring_show_fdinfo() 2025-05-14 07:15:28 -06:00
ipc treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
kernel locking/mutex: implement mutex_lock_killable_nest_lock 2025-05-27 12:16:41 -04:00
lib KVM: arm64: Introduce CONFIG_UBSAN_KVM_EL2 2025-05-07 11:21:35 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm Nine singleton hotfixes, all MM. Four are cc:stable. 2025-05-17 10:56:52 -07:00
net net: devmem: fix kernel panic when netlink socket close after module unload 2025-05-15 08:05:32 -07:00
rust rust: clean Rust 1.88.0's clippy::uninlined_format_args lint 2025-05-07 00:11:47 +02:00
samples tracing: samples: Initialize trace_array_printk() with the correct function 2025-05-12 13:07:22 -04:00
scripts KVM/arm64 updates for 6.16 2025-05-26 16:19:46 -04:00
security landlock: Improve bit operations in audit code 2025-05-12 11:38:53 +02:00
sound ALSA: usb-audio: Add sample rate quirk for Microdia JP001 USB Camera 2025-05-15 12:45:48 +02:00
tools KVM/riscv changes for 6.16 2025-05-26 16:27:00 -04:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt KVM: add kvm_lock_all_vcpus and kvm_trylock_all_vcpus 2025-05-27 12:16:41 -04:00
.clang-format clang-format: Update the ForEachMacros list for v6.15-rc1 2025-04-13 11:03:59 +02:00
.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: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: Create intermediate vmlinux build with relocations preserved 2025-03-17 00:29:50 +09:00
.mailmap soc: fixes for 6.15, part 2 2025-05-14 09:11:05 -07:00
.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: update SLAB ALLOCATOR maintainers 2025-04-17 20:10:06 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS KVM: selftests: Add supported test cases for LoongArch 2025-05-20 20:20:26 +08:00
Makefile Linux 6.15-rc7 2025-05-18 13:57:29 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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.