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  1. Feb 01, 2012
    • Stephan Bärwolf's avatar
      KVM: x86: extend "struct x86_emulate_ops" with "get_cpuid" · bdb42f5a
      Stephan Bärwolf authored
      
      
      In order to be able to proceed checks on CPU-specific properties
      within the emulator, function "get_cpuid" is introduced.
      With "get_cpuid" it is possible to virtually call the guests
      "cpuid"-opcode without changing the VM's context.
      
      [mtosatti: cleanup/beautify code]
      
      Signed-off-by: default avatarStephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>
      Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
      bdb42f5a
    • Takuya Yoshikawa's avatar
      KVM: Fix __set_bit() race in mark_page_dirty() during dirty logging · 50e92b3c
      Takuya Yoshikawa authored
      
      
      It is possible that the __set_bit() in mark_page_dirty() is called
      simultaneously on the same region of memory, which may result in only
      one bit being set, because some callers do not take mmu_lock before
      mark_page_dirty().
      
      This problem is hard to produce because when we reach mark_page_dirty()
      beginning from, e.g., tdp_page_fault(), mmu_lock is being held during
      __direct_map():  making kvm-unit-tests' dirty log api test write to two
      pages concurrently was not useful for this reason.
      
      So we have confirmed that there can actually be race condition by
      checking if some callers really reach there without holding mmu_lock
      using spin_is_locked():  probably they were from kvm_write_guest_page().
      
      To fix this race, this patch changes the bit operation to the atomic
      version:  note that nr_dirty_pages also suffers from the race but we do
      not need exactly correct numbers for now.
      
      Signed-off-by: default avatarTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
      Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
      50e92b3c
  2. Jan 25, 2012
  3. Jan 24, 2012