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151104a7b3
linux/arch/x86
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Takuya Yoshikawa 6dbf79e716 KVM: Fix write protection race during dirty logging 
This patch fixes a race introduced by:

  commit 95d4c16ce7
  KVM: Optimize dirty logging by rmap_write_protect()

During protecting pages for dirty logging, other threads may also try
to protect a page in mmu_sync_children() or kvm_mmu_get_page().

In such a case, because get_dirty_log releases mmu_lock before flushing
TLB's, the following race condition can happen:

  A (get_dirty_log)     B (another thread)

  lock(mmu_lock)
  clear pte.w
  unlock(mmu_lock)
                        lock(mmu_lock)
                        pte.w is already cleared
                        unlock(mmu_lock)
                        skip TLB flush
                        return
  ...
  TLB flush

Though thread B assumes the page has already been protected when it
returns, the remaining TLB entry will break that assumption.

This patch fixes this problem by making get_dirty_log hold the mmu_lock
until it flushes the TLB's.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2012-03-08 14:10:12 +02:00
..
boot x86/boot-image: Don't leak phdrs in arch/x86/boot/compressed/misc.c::Parse_elf() 2012-01-26 11:30:29 +01:00
configs
crypto
ia32 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit 2012-01-17 16:41:31 -08:00
include/asm KVM: Track TSC synchronization in generations 2012-03-08 14:10:09 +02:00
kernel x86: Introduce x86_cpuinit.early_percpu_clock_init hook 2012-03-05 14:57:32 +02:00
kvm KVM: Fix write protection race during dirty logging 2012-03-08 14:10:12 +02:00
lguest lguest: Make sure interrupt is allocated ok by lguest_setup_irq 2012-01-12 15:44:47 +10:30
lib Merge branches 'sched-urgent-for-linus', 'perf-urgent-for-linus' and 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-01-19 14:53:06 -08:00
math-emu
mm Merge branches 'core-urgent-for-linus', 'perf-urgent-for-linus', 'sched-urgent-for-linus' and 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-02-02 11:11:13 -08:00
net net: bpf_jit: fix divide by 0 generation 2012-01-18 16:04:26 -05:00
oprofile
pci xen pvhvm: do not remap pirqs onto evtchns if !xen_have_vector_callback 2012-02-03 16:06:27 -05:00
platform x86/uv: Fix uninitialized spinlocks 2012-01-26 10:58:34 +01:00
power
syscalls
tools
um uml: fix compile for x86-64 2012-01-18 19:26:11 -08:00
vdso
video
xen xen/pat: Disable PAT support for now. 2012-02-20 10:41:35 -05:00
.gitignore x86/kprobes: Add arch/x86/tools/insn_sanity to .gitignore 2012-01-16 08:21:59 +01:00
Kbuild
Kconfig x86/numachip: Drop unnecessary conflict with EDAC 2012-01-26 11:03:03 +01:00
Kconfig.cpu mm,x86,um: move CMPXCHG_DOUBLE config option 2012-01-12 20:13:03 -08:00
Kconfig.debug Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-01-11 19:13:40 -08:00
Makefile
Makefile_32.cpu
Makefile.um