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Sean Christopherson 281a4e5f10 KVM: nVMX: Synthesize SHUTDOWN on RSM if L2 requires emulation
Synthesize SHUTDOWN (for L1) if L2 requires unhandleable emulation after
loading guest state from SMRAM during RSM to prevent a misbehaving L1 (or
userspace via L1) from tripping the sanity check that KVM doesn't try to
cancel a pending nested VM-Enter.  If SMRAM is modified such that RSM will
load what should be impossible state for L2, then KVM will detect that it
needs to emulate the current code stream and will abort VM-Entry to L2.
And because KVM (rightly) expects such a scenario to be impossible, KVM
WARNs and bugs the VM.

  __ret && !(vcpu->kvm)->vm_bugged
  WARNING: arch/x86/kvm/vmx/vmx.c:6741 at vmx_handle_exit+0x65/0x790 [kvm_intel], CPU#13: vmx_invalid_nes/2902
  Modules linked in: kvm_intel kvm irqbypass [last unloaded: kvm]
  CPU: 13 UID: 1000 PID: 2902 Comm: vmx_invalid_nes Tainted: G        W 7.2.0-rc2 #124 PREEMPT
  Tainted: [W]=WARN
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
  RIP: 0010:vmx_handle_exit+0x65/0x790 [kvm_intel]
  Call Trace:
   <TASK>
   kvm_arch_vcpu_ioctl_run+0xdf8/0x1d00 [kvm]
   kvm_vcpu_ioctl+0x2d5/0x960 [kvm]
   __x64_sys_ioctl+0x8a/0xd0
   do_syscall_64+0xb7/0x570
   entry_SYSCALL_64_after_hwframe+0x4b/0x53
   </TASK>

Alternatively, KVM could suppress the WARN for the RSM case, but that would
still leave the vCPU in a "bad" state that KVM doesn't know how to handle
(which is also why KVM rejects attempts to do KVM_RUN when the vCPU is
loaded with invalid state).  And architecturally, the Intel SDM explicitly
states that RSM leads to shutdown if the CPU detects invalid state.

Fixes: 2bb8cafea8 ("KVM: vVMX: signal failure for nested VMEntry if emulation_required")
Reported-by: Hao Zhang <zhanghao1@kylinos.cn>
Link: https://patch.msgid.link/20260731173340.2644656-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
History 2026-07-31 14:03:08 -07:00
arch KVM: nVMX: Synthesize SHUTDOWN on RSM if L2 requires emulation 2026-07-31 14:03:08 -07:00
block block-7.1-20260529 2026-05-29 10:41:07 -07:00
certs Clang build fixes for 7.1 2026-04-24 09:29:51 -07:00
crypto crypto/krb5, rxrpc: Fix lack of pre-decrypt/pre-verify length checks 2026-05-20 16:36:45 -07:00
Documentation KVM: s390: Fix S390_USER_OPEREXEC and more gmap fixes 2026-06-24 13:41:41 +02:00
drivers KVM: s390: Fix S390_USER_OPEREXEC and more gmap fixes 2026-06-24 13:41:41 +02:00
fs namespace: restrict OPEN_TREE_NAMESPACE/FSMOUNT_NAMESPACE to directories 2026-06-10 07:09:20 -07:00
include KVM: nSVM: Add CLASS()es for automagically handling local kvm_vcpu_map() usage 2026-07-28 13:48:43 -07:00
init memblock: updates for 7.0-rc1 2026-04-18 11:29:14 -07:00
io_uring io_uring-7.1-20260611 2026-06-12 10:49:59 -07:00
ipc ipc/shm: serialize orphan cleanup with shm_nattch updates 2026-06-03 16:25:49 -07:00
kernel dma-mapping fixes for Linux 7.1 2026-06-11 14:22:26 -07:00
lib - Fix potential debugobjects deadlock on PREEMPT_RT kernels 2026-06-13 08:23:36 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm 11 hotfixes. 9 are for MM. 8 are cc:stable and the remaining 3 2026-06-09 08:24:25 -07:00
net netfilter pull request 26-06-10 2026-06-11 12:30:00 +02:00
rust rust: i2c: fix I2cAdapter refcount double increment 2026-06-08 09:47:50 +02:00
samples soc: drivers for 7.1 2026-04-16 20:34:34 -07:00
scripts Rust fixes for v7.1 (2nd) 2026-06-06 09:44:42 -07:00
security security/keys: fix missed RCU read section on lookup 2026-05-28 11:45:41 -07:00
sound ASoC: Fixes for v7.1 2026-06-11 21:29:47 +02:00
tools KVM: selftests: Extend set_sregs test to cover EFER 2026-07-27 12:43:56 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt KVM: Harden kvm_vcpu_map() against double-mapping and thus leaking references 2026-07-28 13:48:46 -07:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add myself 2026-04-02 16:48:25 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rust: provide an option to inline C helpers into Rust 2026-03-30 02:03:52 +02:00
.mailmap MAINTAINERS: update Baoquan He's email address 2026-06-03 16:25:50 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.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 Delete some obsolete networking code 2026-04-24 09:41:58 -07:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS KVM: s390: Fix S390_USER_OPEREXEC and more gmap fixes 2026-06-24 13:41:41 +02:00
Makefile Linux 7.1 2026-06-14 15:58:38 +01:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -07:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros
* AI Coding Assistant - LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst