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Sean Christopherson 17bcd71442 KVM: x86: Free vCPUs before freeing VM state 
Free vCPUs before freeing any VM state, as both SVM and VMX may access
VM state when "freeing" a vCPU that is currently "in" L2, i.e. that needs
to be kicked out of nested guest mode.

Commit 6fcee03df6 ("KVM: x86: avoid loading a vCPU after .vm_destroy was
called") partially fixed the issue, but for unknown reasons only moved the
MMU unloading before VM destruction.  Complete the change, and free all
vCPU state prior to destroying VM state, as nVMX accesses even more state
than nSVM.

In addition to the AVIC, KVM can hit a use-after-free on MSR filters:

  kvm_msr_allowed+0x4c/0xd0
  __kvm_set_msr+0x12d/0x1e0
  kvm_set_msr+0x19/0x40
  load_vmcs12_host_state+0x2d8/0x6e0 [kvm_intel]
  nested_vmx_vmexit+0x715/0xbd0 [kvm_intel]
  nested_vmx_free_vcpu+0x33/0x50 [kvm_intel]
  vmx_free_vcpu+0x54/0xc0 [kvm_intel]
  kvm_arch_vcpu_destroy+0x28/0xf0
  kvm_vcpu_destroy+0x12/0x50
  kvm_arch_destroy_vm+0x12c/0x1c0
  kvm_put_kvm+0x263/0x3c0
  kvm_vm_release+0x21/0x30

and an upcoming fix to process injectable interrupts on nested VM-Exit
will access the PIC:

  BUG: kernel NULL pointer dereference, address: 0000000000000090
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  CPU: 23 UID: 1000 PID: 2658 Comm: kvm-nx-lpage-re
  RIP: 0010:kvm_cpu_has_extint+0x2f/0x60 [kvm]
  Call Trace:
   <TASK>
   kvm_cpu_has_injectable_intr+0xe/0x60 [kvm]
   nested_vmx_vmexit+0x2d7/0xdf0 [kvm_intel]
   nested_vmx_free_vcpu+0x40/0x50 [kvm_intel]
   vmx_vcpu_free+0x2d/0x80 [kvm_intel]
   kvm_arch_vcpu_destroy+0x2d/0x130 [kvm]
   kvm_destroy_vcpus+0x8a/0x100 [kvm]
   kvm_arch_destroy_vm+0xa7/0x1d0 [kvm]
   kvm_destroy_vm+0x172/0x300 [kvm]
   kvm_vcpu_release+0x31/0x50 [kvm]

Inarguably, both nSVM and nVMX need to be fixed, but punt on those
cleanups for the moment.  Conceptually, vCPUs should be freed before VM
state.  Assets like the I/O APIC and PIC _must_ be allocated before vCPUs
are created, so it stands to reason that they must be freed _after_ vCPUs
are destroyed.

Reported-by: Aaron Lewis <aaronlewis@google.com>
Closes: https://lore.kernel.org/all/20240703175618.2304869-2-aaronlewis@google.com
Cc: Jim Mattson <jmattson@google.com>
Cc: Yan Zhao <yan.y.zhao@intel.com>
Cc: Rick P Edgecombe <rick.p.edgecombe@intel.com>
Cc: Kai Huang <kai.huang@intel.com>
Cc: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20250224235542.2562848-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-02-26 04:17:15 -05:00
arch KVM: x86: Free vCPUs before freeing VM state 2025-02-26 04:17:15 -05:00
block block-6.14-20250214 2025-02-14 11:40:59 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
Documentation Driver core api addition for 6.14-rc3 2025-02-16 12:54:42 -08:00
drivers Driver core api addition for 6.14-rc3 2025-02-16 12:54:42 -08:00
fs SMB3 client multichannel fix 2025-02-14 14:42:52 -08:00
include Driver core api addition for 6.14-rc3 2025-02-16 12:54:42 -08:00
init Kbuild updates for v6.14 2025-01-31 12:07:07 -08:00
io_uring io_uring-6.14-20250214 2025-02-14 11:30:53 -08:00
ipc treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
kernel - Remove an unused config item GENERIC_PENDING_IRQ_CHIPFLAGS 2025-02-16 10:55:17 -08:00
lib hardening fixes for v6.14-rc2 2025-02-08 14:12:17 -08:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm assorted stuff for this merge window 2025-02-01 15:07:56 -08:00
net Including fixes from netfilter, wireless and bluetooth. 2025-02-13 12:17:04 -08:00
rust Driver core api addition for 6.14-rc3 2025-02-16 12:54:42 -08:00
samples Driver core api addition for 6.14-rc3 2025-02-16 12:54:42 -08:00
scripts modpost: Fix a few typos in a comment 2025-02-16 03:10:58 +09:00
security Redo of pathname patternization and fix spelling errors. 2025-02-11 10:19:36 -08:00
sound sound fixes for 6.14-rc1 2025-01-31 09:17:02 -08:00
tools - Move a warning about a lld.ld breakage into the verbose setting as said 2025-02-16 10:30:58 -08:00
usr kbuild: Drop support for include/asm-<arch> in headers_check.pl 2024-12-21 11:43:17 +09:00
virt KVM: remove kvm_arch_post_init_vm 2025-02-04 11:27:45 -05:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-01-10 00:17:25 +01:00
.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 MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: use host dylib naming convention to support macOS 2025-01-10 01:01:24 +01:00
.mailmap wireless fixes for v6.14-rc3 2025-02-10 18:13:07 -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: Move Pavel to kernel.org address 2025-02-07 09:12:33 -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 Driver core api addition for 6.14-rc3 2025-02-16 12:54:42 -08:00
Makefile Linux 6.14-rc3 2025-02-16 14:02:44 -08:00
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.