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Jim Mattson 63fada2960 KVM: VMX: Execute IBPB on emulated VM-exit when guest has IBRS 
[ Upstream commit 2e7eab8142 ]

According to Intel's document on Indirect Branch Restricted
Speculation, "Enabling IBRS does not prevent software from controlling
the predicted targets of indirect branches of unrelated software
executed later at the same predictor mode (for example, between two
different user applications, or two different virtual machines). Such
isolation can be ensured through use of the Indirect Branch Predictor
Barrier (IBPB) command." This applies to both basic and enhanced IBRS.

Since L1 and L2 VMs share hardware predictor modes (guest-user and
guest-kernel), hardware IBRS is not sufficient to virtualize
IBRS. (The way that basic IBRS is implemented on pre-eIBRS parts,
hardware IBRS is actually sufficient in practice, even though it isn't
sufficient architecturally.)

For virtual CPUs that support IBRS, add an indirect branch prediction
barrier on emulated VM-exit, to ensure that the predicted targets of
indirect branches executed in L1 cannot be controlled by software that
was executed in L2.

Since we typically don't intercept guest writes to IA32_SPEC_CTRL,
perform the IBPB at emulated VM-exit regardless of the current
IA32_SPEC_CTRL.IBRS value, even though the IBPB could technically be
deferred until L1 sets IA32_SPEC_CTRL.IBRS, if IA32_SPEC_CTRL.IBRS is
clear at emulated VM-exit.

This is CVE-2022-2196.

Fixes: 5c911beff2 ("KVM: nVMX: Skip IBPB when switching between vmcs01 and vmcs02")
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221019213620.1953281-3-jmattson@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-02-25 11:25:40 +01:00
arch KVM: VMX: Execute IBPB on emulated VM-exit when guest has IBRS 2023-02-25 11:25:40 +01:00
block block, bfq: fix uaf for bfqq in bic_set_bfqq() 2023-02-09 11:28:06 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto use less confusing names for iov_iter direction initializers 2023-02-09 11:28:04 +01:00
Documentation docs: perf: Fix PMU instance name of hisi-pcie-pmu 2023-02-25 11:25:39 +01:00
drivers spi: mediatek: Enable irq when pdata is ready 2023-02-25 11:25:39 +01:00
fs revert "squashfs: harden sanity check in squashfs_read_xattr_id_table" 2023-02-22 12:59:50 +01:00
include scsi: libsas: Add smp_ata_check_ready_type() 2023-02-25 11:25:39 +01:00
init gcc: disable -Warray-bounds for gcc-11 too 2023-01-14 10:33:43 +01:00
io_uring use less confusing names for iov_iter direction initializers 2023-02-09 11:28:04 +01:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel sched/psi: Stop relying on timer_pending() for poll_work rescheduling 2023-02-25 11:25:39 +01:00
lib maple_tree: fix mas_empty_area_rev() lower bound validation 2023-02-09 11:28:23 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/gup: add folio to list when folio_isolate_lru() succeed 2023-02-22 12:59:54 +01:00
net net: sched: sch: Fix off by one in htb_activate_prios() 2023-02-22 12:59:56 +01:00
rust rust: print: avoid evaluating arguments in pr_* macros in unsafe blocks 2023-02-06 08:06:34 +01:00
samples ftrace: Export ftrace_free_filter() to modules 2023-02-01 08:34:37 +01:00
scripts kbuild: modinst: Fix build error when CONFIG_MODULE_SIG_KEY is a PKCS#11 URI 2023-02-09 11:28:11 +01:00
security use less confusing names for iov_iter direction initializers 2023-02-09 11:28:04 +01:00
sound ASoC: SOF: Intel: hda-dai: fix possible stream_tag leak 2023-02-22 12:59:56 +01:00
tools Revert "mm: Always release pages to the buddy allocator in memblock_free_late()." 2023-02-22 12:59:50 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: Fix potential deadlock on vfio group_lock 2023-02-01 08:34:36 +01:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -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 Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
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 panic: Expose "warn_count" to sysfs 2023-01-24 07:24:41 +01:00
Makefile Linux 6.1.13 2023-02-22 12:59:56 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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 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.