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Sandipan Das c0f9596a44 KVM: x86/pmu: Do not mask LVTPC when handling a PMI on AMD platforms 
commit 49ff3b4aec upstream.

On AMD and Hygon platforms, the local APIC does not automatically set
the mask bit of the LVTPC register when handling a PMI and there is
no need to clear it in the kernel's PMI handler.

For guests, the mask bit is currently set by kvm_apic_local_deliver()
and unless it is cleared by the guest kernel's PMI handler, PMIs stop
arriving and break use-cases like sampling with perf record.

This does not affect non-PerfMonV2 guests because PMIs are handled in
the guest kernel by x86_pmu_handle_irq() which always clears the LVTPC
mask bit irrespective of the vendor.

Before:

  $ perf record -e cycles:u true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.001 MB perf.data (1 samples) ]

After:

  $ perf record -e cycles:u true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.002 MB perf.data (19 samples) ]

Fixes: a16eb25b09 ("KVM: x86: Mask LVTPC when handling a PMI")
Cc: stable@vger.kernel.org
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
[sean: use is_intel_compatible instead of !is_amd_or_hygon()]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240405235603.1173076-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2024-04-27 17:13:01 +02:00
Documentation x86/bugs: Remove CONFIG_BHI_MITIGATION_AUTO and spectre_bhi=auto 2024-04-17 11:23:41 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
arch KVM: x86/pmu: Do not mask LVTPC when handling a PMI on AMD platforms 2024-04-27 17:13:01 +02:00
block block: propagate partition scanning errors to the BLKRRPART ioctl 2024-04-27 17:12:57 +02:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto Revert "crypto: pkcs7 - remove sha1 support" 2024-04-03 15:32:31 +02:00
drivers speakup: Avoid crash on very long word 2024-04-27 17:13:01 +02:00
fs fs: sysfs: Fix reference leak in sysfs_break_active_protection() 2024-04-27 17:13:01 +02:00
include sched: Add missing memory barrier in switch_mm_cid 2024-04-27 17:13:01 +02:00
init fs/proc: Skip bootloader comment if no embedded kernel parameters 2024-04-17 11:23:36 +02:00
io_uring io_uring: Fix io_cqring_wait() not restoring sigmask on get_timespec64() failure 2024-04-27 17:12:47 +02:00
ipc shm: Slim down dependencies 2023-12-20 19:26:31 -05:00
kernel sched: Add missing memory barrier in switch_mm_cid 2024-04-27 17:13:01 +02:00
lib lib: checksum: hide unused expected_csum_ipv6_magic[] 2024-04-17 11:23:28 +02:00
mm userfaultfd: change src_folio after ensuring it's unpinned in UFFDIO_MOVE 2024-04-27 17:12:54 +02:00
net net/sched: Fix mirred deadlock on device recursion 2024-04-27 17:12:53 +02:00
rust Rust changes for v6.8 2024-01-11 13:05:41 -08:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-09 15:57:48 -08:00
scripts gcc-plugins/stackleak: Avoid .head.text section 2024-04-13 13:10:11 +02:00
security selinux: avoid dereference of garbage after mount failure 2024-04-10 16:38:01 +02:00
sound ALSA: hda/realtek - Enable audio jacks of Haier Boyue G42 with ALC269VC 2024-04-27 17:12:57 +02:00
tools selftests/powerpc/papr-vpd: Fix missing variable initialization 2024-04-27 17:12:56 +02:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-03 15:32:03 +02:00
.clang-format clang-format: Update with v6.7-rc4's `for_each` macro list 2023-12-08 23:54:38 +01:00
.cocciconfig
…
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.mailmap drm fixes for 6.8 final 2024-03-08 12:44:56 -08:00
.rustfmt.toml rust: add `.rustfmt.toml` 2022-09-28 09:02:20 +02:00
COPYING
…
CREDITS MAINTAINERS: supplement of zswap maintainers update 2024-01-25 23:52:21 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
…
MAINTAINERS drm fixes for 6.8 final 2024-03-08 12:44:56 -08:00
Makefile Linux 6.8.7 2024-04-17 11:23:43 +02:00
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.