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Filename Latest commit message Latest commit date
Sean Christopherson 24efe61f69 KVM: x86/mmu: WARN if zapping a MMIO spte results in zapping children
Paolo expressed a concern that kvm_mmu_zap_mmio_sptes() could have a
quadratic runtime[1], i.e. restarting the spte walk while zapping only
MMIO sptes could result in re-walking large portions of the list over
and over due to the non-MMIO sptes encountered before the restart not
being removed.

At the time, the concern was legitimate as the walk was restarted when
any spte was zapped.  But that is no longer the case as the walk is now
restarted iff one or more children have been zapped, which is necessary
because zapping children makes the active_mmu_pages list unstable.

Furthermore, it should be impossible for an MMIO spte to have children,
i.e. zapping an MMIO spte should never result in zapping children.  In
other words, kvm_mmu_zap_mmio_sptes() should never restart its walk, and
so should always execute in linear time.  WARN if this assertion fails.

Although it should never be needed, leave the restart logic in place.
In normal operation, the cost is at worst an extra CMP+Jcc, and if for
some reason the list does become unstable, not restarting would likely
crash KVM, or worse, the kernel.

[1] https://patchwork.kernel.org/patch/10756589/#22452085

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-02-20 22:48:48 +01:00
arch KVM: x86/mmu: WARN if zapping a MMIO spte results in zapping children 2019-02-20 22:48:48 +01:00
block for-linus-20190209 2019-02-09 10:26:09 -08:00
certs kbuild: remove redundant target cleaning on failure 2019-01-06 09:46:51 +09:00
crypto crypto: sm3 - fix undefined shift by >= width of value 2019-01-10 21:37:32 +08:00
Documentation Revert "KVM: MMU: document fast invalidate all pages" 2019-02-20 22:48:39 +01:00
drivers dmaengine-fix-5.0-rc6 2019-02-10 10:39:37 -08:00
firmware kbuild: change filechk to surround the given command with { } 2019-01-06 09:46:51 +09:00
fs for-linus-20190209 2019-02-09 10:26:09 -08:00
include KVM: Move the memslot update in-progress flag to bit 63 2019-02-20 22:48:37 +01:00
init psi: clarify the Kconfig text for the default-disable option 2019-02-01 15:46:24 -08:00
ipc
kernel Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-02-10 09:48:18 -08:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-02-08 11:21:54 -08:00
LICENSES
mm mm: migrate: don't rely on __PageMovable() of newpage after unlocking it 2019-02-01 15:46:24 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-02-08 11:21:54 -08:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-01-30 15:24:45 +01:00
scripts Bug fixes for gcc-plugins 2019-01-21 13:07:03 +13:00
security apparmor: Fix aa_label_build() error handling for failed merges 2019-02-01 08:01:39 -08:00
sound sound fixes for 5.0-rc6 2019-02-07 08:33:56 +00:00
tools selftests: kvm: add selftest for releasing VM file descriptor while in L2 2019-02-12 13:12:12 +01:00
usr
virt KVM: Move the memslot update in-progress flag to bit 63 2019-02-20 22:48:37 +01:00
.clang-format clang-format: Update .clang-format with the latest for_each macro list 2019-01-19 19:26:06 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap A few early MIPS fixes for 4.21: 2019-01-05 12:48:25 -08:00
COPYING
CREDITS
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig
MAINTAINERS Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2019-02-09 13:43:12 -08:00
Makefile Linux 5.0-rc6 2019-02-10 14:42:20 -08:00
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.