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Filename Latest commit message Latest commit date
Sean Christopherson 64b8f33b2e KVM: nVMX: Skip IBPB when switching between vmcs01 and vmcs02
commit 5c911beff20aa8639e7a1f28988736c13e03ed54 upstream.

Skip the Indirect Branch Prediction Barrier that is triggered on a VMCS
switch when running with spectre_v2_user=on/auto if the switch is
between two VMCSes in the same guest, i.e. between vmcs01 and vmcs02.
The IBPB is intended to prevent one guest from attacking another, which
is unnecessary in the nested case as it's the same guest from KVM's
perspective.

This all but eliminates the overhead observed for nested VMX transitions
when running with CONFIG_RETPOLINE=y and spectre_v2_user=on/auto, which
can be significant, e.g. roughly 3x on current systems.

Reported-by: Alexander Graf <graf@amazon.com>
Cc: KarimAllah Raslan <karahmed@amazon.de>
Cc: stable@vger.kernel.org
Fixes: 15d4507152 ("KVM/x86: Add IBPB support")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200501163117.4655-1-sean.j.christopherson@intel.com>
[Invert direction of bool argument. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-17 16:40:34 +02:00
arch KVM: nVMX: Skip IBPB when switching between vmcs01 and vmcs02 2020-06-17 16:40:34 +02:00
block Revert "block: end bio with BLK_STS_AGAIN in case of non-mq devs and REQ_NOWAIT" 2020-06-03 08:21:27 +02:00
certs
crypto crypto: drbg - fix error return code in drbg_alloc_state() 2020-06-17 16:40:31 +02:00
Documentation lib/lzo: fix ambiguous encoding bug in lzo-rle 2020-06-17 16:40:28 +02:00
drivers video: fbdev: w100fb: Fix a potential double free. 2020-06-17 16:40:33 +02:00
fs proc: Use new_inode not new_inode_pseudo 2020-06-17 16:40:33 +02:00
include dccp: Fix possible memleak in dccp_init and dccp_fini 2020-06-17 16:40:32 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel padata: add separate cpuhp node for CPUHP_PADATA_DEAD 2020-06-17 16:40:22 +02:00
lib lib/lzo: fix ambiguous encoding bug in lzo-rle 2020-06-17 16:40:28 +02:00
LICENSES
mm gup: document and work around "COW can break either way" issue 2020-06-17 16:40:30 +02:00
net dccp: Fix possible memleak in dccp_init and dccp_fini 2020-06-17 16:40:32 +02:00
samples samples: bpf: Fix build error 2020-06-03 08:21:15 +02:00
scripts bpf: Support llvm-objcopy for vmlinux BTF 2020-06-17 16:40:20 +02:00
security mm: add kvfree_sensitive() for freeing sensitive data objects 2020-06-17 16:40:23 +02:00
sound ALSA: usb-audio: Add vendor, product and profile name for HP Thunderbolt Dock 2020-06-17 16:40:28 +02:00
tools selftests/net: in rxtimestamp getopt_long needs terminating null entry 2020-06-17 16:40:32 +02:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: x86: Fix APIC page invalidation race 2020-06-17 16:40:26 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 17:22:19 +01:00
Makefile Linux 5.4.46 2020-06-10 20:24:58 +02:00
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.