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Filename Latest commit message Latest commit date
Ben Gardon 92da008fa2 Revert "KVM/MMU: Flush tlb directly in the kvm_zap_gfn_range()"
This reverts commit 71883a62fc.

The above commit contains an optimization to kvm_zap_gfn_range which
uses gfn-limited TLB flushes, if enabled. If using these limited flushes,
kvm_zap_gfn_range passes lock_flush_tlb=false to slot_handle_level_range
which creates a race when the function unlocks to call cond_resched.
See an example of this race below:

CPU 0                   CPU 1                           CPU 3
// zap_direct_gfn_range
mmu_lock()
// *ptep == pte_1
*ptep = 0
if (lock_flush_tlb)
        flush_tlbs()
mmu_unlock()
                        // In invalidate range
                        // MMU notifier
                        mmu_lock()
                        if (pte != 0)
                                *ptep = 0
                                flush = true
                        if (flush)
                                flush_remote_tlbs()
                        mmu_unlock()
                        return
                        // Host MM reallocates
                        // page previously
                        // backing guest memory.
                                                        // Guest accesses
                                                        // invalid page
                                                        // through pte_1
                                                        // in its TLB!!

Tested: Ran all kvm-unit-tests on a Intel Haswell machine with and
	without this patch. The patch introduced no new failures.

Signed-off-by: Ben Gardon <bgardon@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-03-15 19:16:45 +01:00
arch Revert "KVM/MMU: Flush tlb directly in the kvm_zap_gfn_range()" 2019-03-15 19:16:45 +01:00
block for-linus-20190209 2019-02-09 10:26:09 -08:00
certs
crypto
Documentation KVM: Expose the initial start value in grow_halt_poll_ns() as a module parameter 2019-02-20 22:48:50 +01:00
drivers KVM/arm updates for Linux v5.1 2019-02-22 17:45:05 +01:00
firmware
fs for-linus-20190209 2019-02-09 10:26:09 -08:00
include KVM/arm updates for Linux v5.1 2019-02-22 17:45:05 +01:00
init
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
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-02-08 11:21:54 -08:00
samples
scripts
security
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/arm updates for Linux v5.1 2019-02-22 17:45:05 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS KVM/arm updates for Linux v5.1 2019-02-22 17:45:05 +01:00
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.