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Sean Christopherson b69b7c1a0d KVM: nVMX: Snapshot pre-VM-Enter BNDCFGS for !nested_run_pending case
commit fa578398a0 upstream.

If a nested run isn't pending, snapshot vmcs01.GUEST_BNDCFGS irrespective
of whether or not VM_ENTRY_LOAD_BNDCFGS is set in vmcs12.  When restoring
nested state, e.g. after migration, without a nested run pending,
prepare_vmcs02() will propagate nested.vmcs01_guest_bndcfgs to vmcs02,
i.e. will load garbage/zeros into vmcs02.GUEST_BNDCFGS.

If userspace restores nested state before MSRs, then loading garbage is a
non-issue as loading BNDCFGS will also update vmcs02.  But if usersepace
restores MSRs first, then KVM is responsible for propagating L2's value,
which is actually thrown into vmcs01, into vmcs02.

Restoring L2 MSRs into vmcs01, i.e. loading all MSRs before nested state
is all kinds of bizarre and ideally would not be supported.  Sadly, some
VMMs do exactly that and rely on KVM to make things work.

Note, there's still a lurking SMM bug, as propagating vmcs01.GUEST_BNDFGS
to vmcs02 across RSM may corrupt L2's BNDCFGS.  But KVM's entire VMX+SMM
emulation is flawed as SMI+RSM should not toouch _any_ VMCS when use the
"default treatment of SMIs", i.e. when not using an SMI Transfer Monitor.

Link: https://lore.kernel.org/all/Yobt1XwOfb5M6Dfa@google.com
Fixes: 62cf9bd811 ("KVM: nVMX: Fix emulation of VM_ENTRY_LOAD_BNDCFGS")
Cc: stable@vger.kernel.org
Cc: Lei Wang <lei4.wang@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220614215831.3762138-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-08-17 14:22:47 +02:00
arch KVM: nVMX: Snapshot pre-VM-Enter BNDCFGS for !nested_run_pending case 2022-08-17 14:22:47 +02:00
block block: fix default IO priority handling again 2022-08-11 13:07:50 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: memneq - move into lib/ 2022-06-22 14:22:03 +02:00
Documentation x86/speculation: Add RSB VM Exit protections 2022-08-11 13:07:54 +02:00
drivers HID: wacom: Don't register pad_input for touch switch 2022-08-17 14:22:47 +02:00
fs lockd: detect and reject lock arguments that overflow 2022-08-17 14:22:47 +02:00
include lockd: detect and reject lock arguments that overflow 2022-08-17 14:22:47 +02:00
init Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug 2022-06-09 10:23:26 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:23:10 +02:00
kernel locking/rwsem: Allow slowpath writer to ignore handoff bit if not set by first waiter 2022-08-03 12:03:56 +02:00
lib ida: don't use BUG_ON() for debugging 2022-07-12 16:35:18 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm page_alloc: fix invalid watermark check on a negative value 2022-08-03 12:03:55 +02:00
net sctp: leave the err path free in sctp_stream_init to sctp_stream_free 2022-08-03 12:03:54 +02:00
samples samples/landlock: Format with clang-format 2022-06-09 10:23:23 +02:00
scripts x86/extable: Rework the exception table mechanics 2022-07-29 17:25:25 +02:00
security lockdown: Fix kexec lockdown bypass with ima policy 2022-07-29 17:25:05 +02:00
sound ALSA: hda/realtek: Add quirk for HP Spectre x360 15-eb0xxx 2022-08-17 14:22:46 +02:00
tools x86/speculation: Add RSB VM Exit protections 2022-08-11 13:07:54 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: Don't null dereference ops->destroy 2022-07-29 17:25:24 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Input: goodix - add a goodix.h header file 2022-07-12 16:34:51 +02:00
Makefile Makefile: link with -z noexecstack --no-warn-rwx-segments 2022-08-17 14:22:44 +02:00
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.