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Filename Latest commit message Latest commit date
Sean Christopherson d7a08882a0 KVM: x86: Unconditionally enable irqs in guest context
On VMX, KVM currently does not re-enable irqs until after it has exited
the guest context.  As a result, a tick that fires in the window between
VM-Exit and guest_exit_irqoff() will be accounted as system time.  While
said window is relatively small, it's large enough to be problematic in
some configurations, e.g. if VM-Exits are consistently occurring a hair
earlier than the tick irq.

Intentionally toggle irqs back off so that guest_exit_irqoff() can be
used in lieu of guest_exit() in order to avoid the save/restore of flags
in guest_exit().  On my Haswell system, "nop; cli; sti" is ~6 cycles,
versus ~28 cycles for "pushf; pop <reg>; cli; push <reg>; popf".

Fixes: f2485b3e0c ("KVM: x86: use guest_exit_irqoff")
Reported-by: Wei Yang <w90p710@gmail.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-07-11 15:10:22 +02:00
arch KVM: x86: Unconditionally enable irqs in guest context 2019-07-11 15:10:22 +02:00
block
certs
crypto
Documentation KVM: x86: PMU Event Filter 2019-07-11 15:08:28 +02:00
drivers
fs
include KVM: x86: PMU Event Filter 2019-07-11 15:08:28 +02:00
init
ipc
kernel Make the GCC 9 warning for sub struct memset go away. 2019-05-26 13:49:40 -07:00
lib
LICENSES
mm
net
samples
scripts
security
sound
tools kvm: selftests: introduce aarch64_vcpu_add_default 2019-06-05 14:14:45 +02:00
usr
virt KVM: Properly check if "page" is valid in kvm_vcpu_unmap 2019-07-10 16:25:39 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS The usual smattering of fixes and tunings that came in too late for the 2019-05-26 13:45:15 -07:00
Makefile Linux 5.2-rc2 2019-05-26 16:49:19 -07:00
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.