github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-31 03:27:03 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph
Linux kernel source tree
1,235,496 Commits 1 Branch 940 Tags 24 GiB
C 96.9%
Assembly 0.9%
Rust 0.6%
Shell 0.6%
Python 0.5%
Other 0.3%
9710794640
Go to file
Paolo Bonzini 9710794640 KVM: x86/pmu: fix masking logic for MSR_CORE_PERF_GLOBAL_CTRL 
When commit c59a1f106f ("KVM: x86/pmu: Add IA32_PEBS_ENABLE
MSR emulation for extended PEBS") switched the initialization of
cpuc->guest_switch_msrs to use compound literals, it screwed up
the boolean logic:

+	u64 pebs_mask = cpuc->pebs_enabled & x86_pmu.pebs_capable;
...
-	arr[0].guest = intel_ctrl & ~cpuc->intel_ctrl_host_mask;
-	arr[0].guest &= ~(cpuc->pebs_enabled & x86_pmu.pebs_capable);
+               .guest = intel_ctrl & (~cpuc->intel_ctrl_host_mask | ~pebs_mask),

Before the patch, the value of arr[0].guest would have been intel_ctrl &
~cpuc->intel_ctrl_host_mask & ~pebs_mask.  The intent is to always treat
PEBS events as host-only because, while the guest runs, there is no way
to tell the processor about the virtual address where to put PEBS records
intended for the host.

Unfortunately, the new expression can be expanded to

	(intel_ctrl & ~cpuc->intel_ctrl_host_mask) | (intel_ctrl & ~pebs_mask)

which makes no sense; it includes any bit that isn't *both* marked as
exclude_guest and using PEBS.  So, reinstate the old logic.  Another
way to write it could be "intel_ctrl & ~(cpuc->intel_ctrl_host_mask |
pebs_mask)", presumably the intention of the author of the faulty.
However, I personally find the repeated application of A AND NOT B to
be a bit more readable.

This shows up as guest failures when running concurrent long-running
perf workloads on the host, and was reported to happen with rcutorture.
All guests on a given host would die simultaneously with something like an
instruction fault or a segmentation violation.

Reported-by: Paul E. McKenney <paulmck@kernel.org>
Analyzed-by: Sean Christopherson <seanjc@google.com>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Cc: stable@vger.kernel.org
Fixes: c59a1f106f ("KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-01-04 16:31:27 +01:00
arch KVM: x86/pmu: fix masking logic for MSR_CORE_PERF_GLOBAL_CTRL 2024-01-04 16:31:27 +01:00
block block-6.7-2023-12-29 2023-12-29 11:41:40 -08:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This push fixes a regression in ahash and hides the Kconfig sub-options for the jitter RNG. 2023-11-09 17:04:58 -08:00
Documentation Char/Misc driver fixes for 6.7-rc7 2023-12-23 11:29:12 -08:00
drivers pci-v6.7-fixes-2 2024-01-03 14:18:57 -08:00
fs tracing fixes for v6.7-rc8: 2024-01-03 11:45:15 -08:00
include locking/osq_lock: Move the definition of optimistic_spin_node into osq_lock.c 2023-12-30 10:25:51 -08:00
init As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
io_uring io_uring/cmd: fix breakage in SOCKET_URING_OP_SIOC* implementation 2023-12-14 16:52:13 -07:00
ipc Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
kernel tracing fixes for v6.7-rc7: 2023-12-30 11:37:35 -08:00
lib 11 hotfixes. 7 are cc:stable and the other 4 address post-6.6 issues or 2023-12-27 16:14:41 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/memory-failure: cast index to loff_t before shifting it 2023-12-20 13:46:20 -08:00
net keys, dns: Fix missing size check of V1 server-list header 2023-12-26 13:15:49 -08:00
rust Kbuild updates for v6.7 2023-11-04 08:07:19 -10:00
samples Landlock updates for v6.7-rc1 2023-11-03 09:28:53 -10:00
scripts get_maintainer: remove stray punctuation when cleaning file emails 2023-12-31 10:57:42 -08:00
security apparmor: Fix move_mount mediation by detecting if source is detached 2024-01-03 12:10:29 -08:00
sound ALSA: hda: cs35l41: Only add SPI CS GPIO if SPI is enabled in kernel 2023-12-21 09:24:01 +01:00
tools 11 hotfixes. 7 are cc:stable and the other 4 address post-6.6 issues or 2023-12-27 16:14:41 -08:00
usr arch: Remove Itanium (IA-64) architecture 2023-09-11 08:13:17 +00:00
virt KVM/arm64 fixes for 6.7, part #2 2023-12-22 18:03:54 -05:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: generate kernel.spec in rpmbuild/SPECS/ 2023-10-03 20:49:09 +09:00
.mailmap 11 hotfixes. 7 are cc:stable and the other 4 address post-6.6 issues or 2023-12-27 16:14:41 -08:00
.rustfmt.toml
COPYING
CREDITS pci-v6.7-fixes-2 2024-01-03 14:18:57 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS pci-v6.7-fixes-2 2024-01-03 14:18:57 -08:00
Makefile Linux 6.7-rc8 2023-12-31 12:51:25 -08:00
README

README 

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 Restructured Text 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.