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Filename Latest commit message Latest commit date
Suravee Suthikulpanit 10ed519fa8 iommu/amd: Remove performance counter pre-initialization test
[ Upstream commit 994d6608efe4a4c8834bdc5014c86f4bc6aceea6 ]

In early AMD desktop/mobile platforms (during 2013), when the IOMMU
Performance Counter (PMC) support was first introduced in
commit 30861ddc9c ("perf/x86/amd: Add IOMMU Performance Counter
resource management"), there was a HW bug where the counters could not
be accessed. The result was reading of the counter always return zero.

At the time, the suggested workaround was to add a test logic prior
to initializing the PMC feature to check if the counters can be programmed
and read back the same value. This has been working fine until the more
recent desktop/mobile platforms start enabling power gating for the PMC,
which prevents access to the counters. This results in the PMC support
being disabled unnecesarily.

Unfortunatly, there is no documentation of since which generation
of hardware the original PMC HW bug was fixed. Although, it was fixed
soon after the first introduction of the PMC. Base on this, we assume
that the buggy platforms are less likely to be in used, and it should
be relatively safe to remove this legacy logic.

Link: https://lore.kernel.org/linux-iommu/alpine.LNX.3.20.13.2006030935570.3181@monopod.intra.ispras.ru/
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201753
Cc: Tj (Elloe Linux) <ml.linux@elloe.vision>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Alexander Monakov <amonakov@ispras.ru>
Cc: David Coe <david.coe@live.co.uk>
Cc: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Tested-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20210409085848.3908-3-suravee.suthikulpanit@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-05-19 10:08:22 +02:00
arch KVM: x86/mmu: Remove the defunct update_pte() paging hook 2021-05-19 10:08:20 +02:00
block block: only update parent bi_status when bio fail 2021-04-16 11:46:38 +02:00
certs certs: Fix blacklist flag type confusion 2021-03-04 10:26:29 +01:00
crypto crypto: rng - fix crypto_rng_reset() refcounting when !CRYPTO_STATS 2021-05-11 14:04:15 +02:00
Documentation dt-bindings: net: ethernet-controller: fix typo in NVMEM 2021-04-14 08:24:18 +02:00
drivers iommu/amd: Remove performance counter pre-initialization test 2021-05-19 10:08:22 +02:00
fs cuse: prevent clone 2021-05-19 10:08:22 +02:00
include i2c: Add I2C_AQ_NO_REP_START adapter quirk 2021-05-19 10:08:22 +02:00
init init/Kconfig: make COMPILE_TEST depend on HAS_IOMEM 2021-04-10 13:34:32 +02:00
ipc
kernel smp: Fix smp_call_function_single_async prototype 2021-05-14 09:44:33 +02:00
lib bug: Remove redundant condition check in report_bug 2021-05-14 09:44:27 +02:00
LICENSES
mm mm/memory-failure: unnecessary amount of unmapping 2021-05-14 09:44:32 +02:00
net mac80211: clear the beacon's CRC after channel switch 2021-05-19 10:08:22 +02:00
samples kfifo: fix ternary sign extension bugs 2021-05-14 09:44:32 +02:00
scripts ftrace: Have recordmcount use w8 to read relp->r_info in arm64_is_fake_mcount 2021-03-09 11:09:39 +01:00
security security: commoncap: fix -Wstringop-overread warning 2021-05-11 14:04:16 +02:00
sound ASoC: rsnd: call rsnd_ssi_master_clk_start() from rsnd_ssi_init() 2021-05-19 10:08:22 +02:00
tools selftests: net: mirror_gre_vlan_bridge_1q: Make an FDB entry static 2021-05-14 09:44:32 +02:00
usr
virt KVM: Stop looking for coalesced MMIO zones if the bus is destroyed 2021-05-14 09:44:15 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
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Kconfig
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Makefile Linux 5.4.119 2021-05-14 09:44:33 +02:00
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.