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Sean Christopherson b3286d64d9 KVM: x86/mmu: Skip the "try unsync" path iff the old SPTE was a leaf SPTE
commit 2867eb782c upstream.

Apply make_spte()'s optimization to skip trying to unsync shadow pages if
and only if the old SPTE was a leaf SPTE, as non-leaf SPTEs in direct MMUs
are always writable, i.e. could trigger a false positive and incorrectly
lead to KVM creating a SPTE without write-protecting or marking shadow
pages unsync.

This bug only affects the TDP MMU, as the shadow MMU only overwrites a
shadow-present SPTE when synchronizing SPTEs (and only 4KiB SPTEs can be
unsync).  Specifically, mmu_set_spte() drops any non-leaf SPTEs *before*
calling make_spte(), whereas the TDP MMU can do a direct replacement of a
page table with the leaf SPTE.

Opportunistically update the comment to explain why skipping the unsync
stuff is safe, as opposed to simply saying "it's someone else's problem".

Cc: stable@vger.kernel.org
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-5-seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-12-14 19:53:58 +01:00
arch KVM: x86/mmu: Skip the "try unsync" path iff the old SPTE was a leaf SPTE 2024-12-14 19:53:58 +01:00
block block: fix bio_split_rw_at to take zone_write_granularity into account 2024-12-14 19:53:15 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: api - Add crypto_clone_tfm 2024-12-14 19:53:51 +01:00
Documentation fs_parser: update mount_api doc to match function signature 2024-12-14 19:53:48 +01:00
drivers soc: qcom: socinfo: fix revision check in qcom_socinfo_probe() 2024-12-14 19:53:57 +01:00
fs jfs: xattr: check invalid xattr size more strictly 2024-12-14 19:53:58 +01:00
include dma: allow dma_get_cache_alignment() to be overridden by the arch code 2024-12-14 19:53:57 +01:00
init initramfs: avoid filename buffer overrun 2024-12-14 19:53:14 +01:00
io_uring io_uring: fix possible deadlock in io_register_iowq_max_workers() 2024-11-17 15:07:21 +01:00
ipc sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table) 2024-08-11 12:35:51 +02:00
kernel rcu-tasks: Fix access non-existent percpu rtpcp variable in rcu_tasks_need_gpcb() 2024-12-14 19:53:56 +01:00
lib lib/buildid: Fix build ID parsing logic 2024-11-22 15:37:32 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: resolve faulty mmap_region() error path behaviour 2024-11-22 15:37:34 +01:00
net ipmr: fix tables suspicious RCU usage 2024-12-14 19:53:52 +01:00
rust rust: macros: provide correct provenance when constructing THIS_MODULE 2024-10-17 15:22:24 +02:00
samples bpf: Fix the xdp_adjust_tail sample prog issue 2024-12-14 19:53:27 +01:00
scripts kconfig: qconf: fix buffer overflow in debug links 2024-10-17 15:22:03 +02:00
security apparmor: fix 'Do simple duplicate message elimination' 2024-12-14 19:53:53 +01:00
sound ASoC: codecs: Fix atomicity violation in snd_soc_component_get_drvdata() 2024-12-14 19:53:58 +01:00
tools selftests/mount_setattr: Fix failures on 64K PAGE_SIZE kernels 2024-12-14 19:53:48 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:46:21 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:21:15 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add leah to 6.1 MAINTAINERS file 2024-05-17 11:56:16 +02:00
Makefile Linux 6.1.119 2024-11-22 15:37:35 +01:00
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.