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Filename Latest commit message Latest commit date
Nicholas Piggin bf365066fb KVM: PPC: Book3S HV P9: Restore host CTRL SPR after guest exit
[ Upstream commit 5088eb4092df12d701af8e0e92860b7186365279 ]

The host CTRL (runlatch) value is not restored after guest exit. The
host CTRL should always be 1 except in CPU idle code, so this can result
in the host running with runlatch clear, and potentially switching to
a different vCPU which then runs with runlatch clear as well.

This has little effect on P9 machines, CTRL is only responsible for some
PMU counter logic in the host and so other than corner cases of software
relying on that, or explicitly reading the runlatch value (Linux does
not appear to be affected but it's possible non-Linux guests could be),
there should be no execution correctness problem, though it could be
used as a covert channel between guests.

There may be microcontrollers, firmware or monitoring tools that sample
the runlatch value out-of-band, however since the register is writable
by guests, these values would (should) not be relied upon for correct
operation of the host, so suboptimal performance or incorrect reporting
should be the worst problem.

Fixes: 95a6432ce9 ("KVM: PPC: Book3S HV: Streamlined guest entry/exit path on P9 for radix guests")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210412014845.1517916-2-npiggin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-05-14 09:44:28 +02:00
arch KVM: PPC: Book3S HV P9: Restore host CTRL SPR after guest exit 2021-05-14 09:44:28 +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 mt7601u: fix always true expression 2021-05-14 09:44:28 +02:00
fs ovl: fix missing revert_creds() on error path 2021-05-14 09:44:16 +02:00
include HID: plantronics: Workaround for double volume key presses 2021-05-14 09:44:26 +02:00
init init/Kconfig: make COMPILE_TEST depend on HAS_IOMEM 2021-04-10 13:34:32 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel sched/debug: Fix cgroup_path[] serialization 2021-05-14 09:44:26 +02:00
lib bug: Remove redundant condition check in report_bug 2021-05-14 09:44:27 +02:00
LICENSES
mm mm: fix race by making init_zero_pfn() early_initcall 2021-04-07 14:47:42 +02:00
net mac80211: bail out if cipher schemes are invalid 2021-05-14 09:44:28 +02:00
samples samples, bpf: Add missing munmap in xdpsock 2021-03-17 17:03:33 +01:00
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: simple-card: fix possible uninitialized single_cpu local variable 2021-05-14 09:44:27 +02:00
tools perf symbols: Fix dso__fprintf_symbols_by_name() to return the number of printed chars 2021-05-14 09:44:26 +02:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
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
CREDITS
Kbuild
Kconfig
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.118 2021-05-11 14:04:18 +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.