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Oliver Upton d0571c3add KVM: arm64: Don't retire aborted MMIO instruction 
commit e735a5da64 upstream.

Returning an abort to the guest for an unsupported MMIO access is a
documented feature of the KVM UAPI. Nevertheless, it's clear that this
plumbing has seen limited testing, since userspace can trivially cause a
WARN in the MMIO return:

  WARNING: CPU: 0 PID: 30558 at arch/arm64/include/asm/kvm_emulate.h:536 kvm_handle_mmio_return+0x46c/0x5c4 arch/arm64/include/asm/kvm_emulate.h:536
  Call trace:
   kvm_handle_mmio_return+0x46c/0x5c4 arch/arm64/include/asm/kvm_emulate.h:536
   kvm_arch_vcpu_ioctl_run+0x98/0x15b4 arch/arm64/kvm/arm.c:1133
   kvm_vcpu_ioctl+0x75c/0xa78 virt/kvm/kvm_main.c:4487
   __do_sys_ioctl fs/ioctl.c:51 [inline]
   __se_sys_ioctl fs/ioctl.c:893 [inline]
   __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:893
   __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
   invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
   el0_svc_common+0x1e0/0x23c arch/arm64/kernel/syscall.c:132
   do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
   el0_svc+0x38/0x68 arch/arm64/kernel/entry-common.c:712
   el0t_64_sync_handler+0x90/0xfc arch/arm64/kernel/entry-common.c:730
   el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

The splat is complaining that KVM is advancing PC while an exception is
pending, i.e. that KVM is retiring the MMIO instruction despite a
pending synchronous external abort. Womp womp.

Fix the glaring UAPI bug by skipping over all the MMIO emulation in
case there is a pending synchronous exception. Note that while userspace
is capable of pending an asynchronous exception (SError, IRQ, or FIQ),
it is still safe to retire the MMIO instruction in this case as (1) they
are by definition asynchronous, and (2) KVM relies on hardware support
for pending/delivering these exceptions instead of the software state
machine for advancing PC.

Cc: stable@vger.kernel.org
Fixes: da345174ce ("KVM: arm/arm64: Allow user injection of external data aborts")
Reported-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241025203106.3529261-2-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-12-05 14:02:44 +01:00
arch KVM: arm64: Don't retire aborted MMIO instruction 2024-12-05 14:02:44 +01:00
block block: fix bio_split_rw_at to take zone_write_granularity into account 2024-12-05 14:01:14 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: pcrypt - Call crypto layer directly when padata_do_parallel() return -EBUSY 2024-12-05 14:01:18 +01:00
Documentation docs: media: update location of the media patches 2024-12-05 14:02:42 +01:00
drivers usb: typec: ucsi: glink: fix off-by-one in connector_status 2024-12-05 14:02:41 +01:00
fs jfs: xattr: check invalid xattr size more strictly 2024-12-05 14:02:42 +01:00
include KVM: x86: switch hugepage recovery thread to vhost_task 2024-12-05 14:02:43 +01:00
init initramfs: avoid filename buffer overrun 2024-12-05 14:01:12 +01:00
io_uring io_uring/rw: fix missing NOWAIT check for O_DIRECT start write 2024-10-31 08:21:02 -06:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel trace/trace_event_perf: remove duplicate samples on the first tracepoint event 2024-12-05 14:02:02 +01:00
lib kasan: move checks to do_strncpy_from_user 2024-12-05 14:02:12 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm/mmap: fix __mmap_region() error handling in rare merge failure case 2024-11-22 15:30:26 +01:00
net net_sched: sch_fq: don't follow the fast path if Tx is behind now 2024-12-05 14:02:40 +01:00
rust rust: block: fix formatting of kernel::block::mq::request module 2024-12-05 14:02:21 +01:00
samples bpf: Fix the xdp_adjust_tail sample prog issue 2024-12-05 14:01:42 +01:00
scripts checkpatch: always parse orig_commit in fixes tag 2024-12-05 14:02:09 +01:00
security apparmor: fix 'Do simple duplicate message elimination' 2024-12-05 14:02:39 +01:00
sound ASoC: da7213: Populate max_register to regmap_config 2024-12-05 14:02:42 +01:00
tools selftests/mount_setattr: Fix failures on 64K PAGE_SIZE kernels 2024-12-05 14:02:28 +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 Linux 6.12.1 2024-11-22 15:30:26 +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.