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Sean Christopherson 85434c3c73 Revert "KVM: VMX: Move LOAD_IA32_PERF_GLOBAL_CTRL errata handling out of setup_vmcs_config()"
Revert back to clearing VM_{ENTRY,EXIT}_LOAD_IA32_PERF_GLOBAL_CTRL in KVM's
golden VMCS config, as applying the workaround during vCPU creation is
pointless and broken.  KVM *unconditionally* clears the controls in the
values returned by vmx_vmentry_ctrl() and vmx_vmexit_ctrl(), as KVM loads
PERF_GLOBAL_CTRL if and only if its necessary to do so.  E.g. if KVM wants
to run the guest with the same PERF_GLOBAL_CTRL as the host, then there's
no need to re-load the MSR on entry and exit.

Even worse, the buggy commit failed to apply the erratum where it's
actually needed, add_atomic_switch_msr().  As a result, KVM completely
ignores the erratum for all intents and purposes, i.e. uses the flawed
VMCS controls to load PERF_GLOBAL_CTRL.

To top things off, the patch was intended to be dropped, as the premise
of an L1 VMM being able to pivot on FMS is flawed, and KVM can (and now
does) fully emulate the controls in software.  Simply revert the commit,
as all upstream supported kernels that have the buggy commit should also
have commit f4c93d1a0e ("KVM: nVMX: Always emulate PERF_GLOBAL_CTRL
VM-Entry/VM-Exit controls"), i.e. the (likely theoretical) live migration
concern is a complete non-issue.

Opportunistically drop the manual "kvm: " scope from the warning about
the erratum, as KVM now uses pr_fmt() to provide the correct scope (v6.1
kernels and earlier don't, but the erratum only applies to CPUs that are
15+ years old; it's not worth a separate patch).

This reverts commit 9d78d6fb18.

Link: https://lore.kernel.org/all/YtnZmCutdd5tpUmz@google.com
Fixes: 9d78d6fb18 ("KVM: VMX: Move LOAD_IA32_PERF_GLOBAL_CTRL errata handling out of setup_vmcs_config()")
Cc: stable@vger.kernel.org
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-ID: <20241119011433.1797921-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
History 2024-11-19 19:34:35 -05:00
arch Revert "KVM: VMX: Move LOAD_IA32_PERF_GLOBAL_CTRL errata handling out of setup_vmcs_config()" 2024-11-19 19:34:35 -05:00
block block-6.12-20241101 2024-11-01 13:41:55 -10:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes the following issues: 2024-10-16 08:42:54 -07:00
Documentation LoongArch KVM changes for v6.13 2024-11-14 07:06:24 -05:00
drivers LoongArch KVM changes for v6.13 2024-11-14 07:06:24 -05:00
fs 20 hotfixes, 14 of which are cc:stable. 2024-11-10 09:04:27 -08:00
include KVM: x86: switch hugepage recovery thread to vhost_task 2024-11-14 13:20:04 -05:00
init cfi: fix conditions for HAVE_CFI_ICALL_NORMALIZE_INTEGERS 2024-10-13 22:23:13 +02:00
io_uring io_uring/rw: fix missing NOWAIT check for O_DIRECT start write 2024-10-31 08:21:02 -06:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel LoongArch KVM changes for v6.13 2024-11-14 07:06:24 -05:00
lib objpool: fix to make percpu slot allocation more robust 2024-11-07 14:14:58 -08:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm filemap: Fix bounds checking in filemap_read() 2024-11-10 14:07:08 -08:00
net Including fixes from can and netfilter. 2024-11-07 11:07:57 -10:00
rust Driver core fix for 6.12-rc3 2024-10-13 09:10:52 -07:00
samples [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
scripts Kbuild fixes for v6.12 (2nd) 2024-11-03 08:29:02 -10:00
security KEYS: trusted: dcp: fix NULL dereference in AEAD crypto operation 2024-11-04 21:24:24 +02:00
sound ASoC: Fixes for v6.12 2024-11-08 09:25:33 +01:00
tools LoongArch KVM changes for v6.13 2024-11-14 07:06:24 -05:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt KVM: x86: switch hugepage recovery thread to vhost_task 2024-11-14 13:20:04 -05:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +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 Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.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: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS sound fixes for 6.12-rc7 2024-11-08 07:44:28 -10:00
Makefile Linux 6.12-rc7 2024-11-10 14:19:35 -08:00
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.