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Filename Latest commit message Latest commit date
Sean Christopherson b68f3cc7d9 KVM: x86: Always use 32-bit SMRAM save state for 32-bit kernels
Invoking the 64-bit variation on a 32-bit kenrel will crash the guest,
trigger a WARN, and/or lead to a buffer overrun in the host, e.g.
rsm_load_state_64() writes r8-r15 unconditionally, but enum kvm_reg and
thus x86_emulate_ctxt._regs only define r8-r15 for CONFIG_X86_64.

KVM allows userspace to report long mode support via CPUID, even though
the guest is all but guaranteed to crash if it actually tries to enable
long mode.  But, a pure 32-bit guest that is ignorant of long mode will
happily plod along.

SMM complicates things as 64-bit CPUs use a different SMRAM save state
area.  KVM handles this correctly for 64-bit kernels, e.g. uses the
legacy save state map if userspace has hid long mode from the guest,
but doesn't fare well when userspace reports long mode support on a
32-bit host kernel (32-bit KVM doesn't support 64-bit guests).

Since the alternative is to crash the guest, e.g. by not loading state
or explicitly requesting shutdown, unconditionally use the legacy SMRAM
save state map for 32-bit KVM.  If a guest has managed to get far enough
to handle SMIs when running under a weird/buggy userspace hypervisor,
then don't deliberately crash the guest since there are no downsides
(from KVM's perspective) to allow it to continue running.

Fixes: 660a5d517a ("KVM: x86: save/load state on SMM switch")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-04-16 15:37:38 +02:00
arch KVM: x86: Always use 32-bit SMRAM save state for 32-bit kernels 2019-04-16 15:37:38 +02:00
block block: Revert v5.0 blk_mq_request_issue_directly() changes 2019-04-05 09:40:46 -06:00
certs
crypto
Documentation ARM: SoC fixes 2019-04-07 13:46:17 -10:00
drivers Bluetooth: btusb: request wake pin with NOAUTOEN 2019-04-09 17:38:24 -10:00
fs Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-04-09 16:20:59 -10:00
include Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-08 17:10:46 -10:00
init
ipc
kernel Merge branch 'akpm' (patches from Andrew) 2019-04-05 17:08:55 -10:00
lib Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-04-09 16:20:59 -10:00
LICENSES
mm slab: fix a crash by reading /proc/slab_allocators 2019-04-07 19:23:12 -10:00
net net: ip6_gre: fix possible use-after-free in ip6erspan_rcv 2019-04-08 16:16:47 -07:00
samples
scripts fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock 2019-04-06 07:01:55 -10:00
security KEYS: trusted: fix -Wvarags warning 2019-04-08 15:58:54 -07:00
sound sound fixes for 5.1-rc3 2019-03-29 14:53:33 -07:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-08 17:10:46 -10:00
usr
virt KVM/ARM fixes for 5.1 2019-03-28 19:07:30 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap Update Nicolas Pitre's email address 2019-04-02 18:12:44 -10:00
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-08 17:10:46 -10:00
Makefile Linux 5.1-rc4 2019-04-07 14:09:59 -10:00
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.