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Like Xu f331601c65 KVM: x86/pmu: Don't generate PEBS records for emulated instructions
KVM will accumulate an enabled counter for at least INSTRUCTIONS or
BRANCH_INSTRUCTION hw event from any KVM emulated instructions,
generating emulated overflow interrupt on counter overflow, which
in theory should also happen when the PEBS counter overflows but
it currently lacks this part of the underlying support (e.g. through
software injection of records in the irq context or a lazy approach).

In this case, KVM skips the injection of this BUFFER_OVF PMI (effectively
dropping one PEBS record) and let the overflow counter move on. The loss
of a single sample does not introduce a loss of accuracy, but is easily
noticeable for certain specific instructions.

This issue is expected to be addressed along with the issue
of PEBS cross-mapped counters with a slow-path proposal.

Fixes: 79f3e3b583 ("KVM: x86/pmu: Reprogram PEBS event to emulate guest PEBS counter")
Signed-off-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20220831085328.45489-3-likexu@tencent.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2022-09-28 12:47:21 -07:00
arch KVM: x86/pmu: Don't generate PEBS records for emulated instructions 2022-09-28 12:47:21 -07:00
block block-6.0-2022-08-12 2022-08-13 13:37:36 -07:00
certs Kbuild updates for v5.20 2022-08-10 10:40:41 -07:00
crypto crypto: blake2b: effectively disable frame size warning 2022-08-10 17:59:11 -07:00
Documentation KVM: remove KVM_REQ_UNHALT 2022-09-26 12:37:21 -04:00
drivers mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses. 2022-08-24 13:51:42 -07:00
fs mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses. 2022-08-24 13:51:42 -07:00
include KVM: remove KVM_REQ_UNHALT 2022-09-26 12:37:21 -04:00
init Kbuild updates for v5.20 2022-08-10 10:40:41 -07:00
io_uring io_uring-6.0-2022-08-13 2022-08-13 13:28:54 -07:00
ipc Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
kernel xen: branch for v6.0-rc1b 2022-08-14 09:28:54 -07:00
lib lib: remove lib/nodemask.c 2022-08-12 09:07:33 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses. 2022-08-24 13:51:42 -07:00
net Including fixes from bluetooth, bpf, can and netfilter. 2022-08-11 13:45:37 -07:00
samples Tracing updates for 5.20 / 6.0 2022-08-05 09:41:12 -07:00
scripts RISC-V Patches for the 5.20 Merge Window, Part 2 2022-08-12 18:39:43 -07:00
security + Features 2022-08-10 10:53:22 -07:00
sound sound fixes for 6.0-rc1 2022-08-12 09:55:32 -07:00
tools KVM: selftests: Don't set reserved bits for invalid Hyper-V hypercall number 2022-09-28 12:47:20 -07:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt KVM: remove KVM_REQ_UNHALT 2022-09-26 12:37:21 -04:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap mailmap: Update Oliver's email address 2022-09-26 12:03:13 -04:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS xen: branch for v6.0-rc1b 2022-08-14 09:28:54 -07:00
Makefile Linux 6.0-rc1 2022-08-14 15:50:18 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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 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.