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Sean Christopherson 55057ec275 KVM: nSVM: Enter guest mode before initializing nested NPT MMU 
commit 46d6c6f3ef upstream.

When preparing vmcb02 for nested VMRUN (or state restore), "enter" guest
mode prior to initializing the MMU for nested NPT so that guest_mode is
set in the MMU's role.  KVM's model is that all L2 MMUs are tagged with
guest_mode, as the behavior of hypervisor MMUs tends to be significantly
different than kernel MMUs.

Practically speaking, the bug is relatively benign, as KVM only directly
queries role.guest_mode in kvm_mmu_free_guest_mode_roots() and
kvm_mmu_page_ad_need_write_protect(), which SVM doesn't use, and in paths
that are optimizations (mmu_page_zap_pte() and
shadow_mmu_try_split_huge_pages()).

And while the role is incorprated into shadow page usage, because nested
NPT requires KVM to be using NPT for L1, reusing shadow pages across L1
and L2 is impossible as L1 MMUs will always have direct=1, while L2 MMUs
will have direct=0.

Hoist the TLB processing and setting of HF_GUEST_MASK to the beginning
of the flow instead of forcing guest_mode in the MMU, as nothing in
nested_vmcb02_prepare_control() between the old and new locations touches
TLB flush requests or HF_GUEST_MASK, i.e. there's no reason to present
inconsistent vCPU state to the MMU.

Fixes: 69cb877487 ("KVM: nSVM: move MMU setup to nested_prepare_vmcb_control")
Cc: stable@vger.kernel.org
Reported-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Link: https://lore.kernel.org/r/20250130010825.220346-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-02-21 14:01:28 +01:00
arch KVM: nSVM: Enter guest mode before initializing nested NPT MMU 2025-02-21 14:01:28 +01:00
block block: don't revert iter for -EIOCBQUEUED 2025-02-17 10:05:19 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: api - Fix boot-up self-test race 2025-02-08 09:57:28 +01:00
Documentation Documentation/networking: fix basic node example document ISO 15765-2 2025-02-21 14:01:16 +01:00
drivers drm/amdgpu: avoid buffer overflow attach in smu_sys_set_pp_table() 2025-02-21 14:01:28 +01:00
fs orangefs: fix a oob in orangefs_debug_write 2025-02-21 14:01:27 +01:00
include kunit: platform: Resolve 'struct completion' warning 2025-02-21 14:01:25 +01:00
init Compiler Attributes: disable __counted_by for clang < 19.1.3 2024-12-05 14:02:45 +01:00
io_uring io_uring/uring_cmd: remove dead req_has_async_data() check 2025-02-21 14:01:20 +01:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-05 14:03:02 +01:00
kernel sched_ext: Use SCX_CALL_OP_TASK in task_tick_scx 2025-02-21 14:01:21 +01:00
lib maple_tree: simplify split calculation 2025-02-17 10:05:42 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm/compaction: fix UBSAN shift-out-of-bounds warning 2025-02-17 10:05:36 +01:00
net batman-adv: Drop unmanaged ELP metric worker 2025-02-21 14:01:28 +01:00
rust rust: init: use explicit ABI to clean warning in future compilers 2025-02-17 10:05:23 +01:00
samples samples/landlock: Fix possible NULL dereference in parse_path() 2025-02-08 09:57:11 +01:00
scripts kbuild: Use -fzero-init-padding-bits=all 2025-02-21 14:01:27 +01:00
security KEYS: trusted: dcp: fix improper sg use with CONFIG_VMAP_STACK=y 2025-02-17 10:05:09 +01:00
sound ASoC: Intel: bytcr_rt5640: Add DMI quirk for Vexia Edu Atla 10 tablet 5V 2025-02-21 14:01:27 +01:00
tools selftests: gpio: gpio-sim: Fix missing chip disablements 2025-02-21 14:01:26 +01:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt KVM: x86: switch hugepage recovery thread to vhost_task 2024-12-05 14:02:43 +01:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -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 self from DSA entry 2024-11-03 12:52:38 -08:00
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: update location of media main tree 2024-12-05 14:02:42 +01:00
Makefile tools: fix annoying "mkdir -p ..." logs when building tools in parallel 2025-02-21 14:01:22 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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 reStructuredText 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.