[PATCH v3 00/10] KVM: MTRR fixes and some cleanups

[Xiao Guangrong]

Changelog in v3:
thanks for Paolo's comment:
- do not apply for_each_rmap_spte to kvm_zap_rmapp and kvm_mmu_unlink_parents
- fix a cosmetic issue in slot_handle_level_range
- introduce PT_MAX_HUGEPAGE_LEVEL to clean up the code
- improve code Indentation

Changelog in v2:
- fix the bit description in changelog of the first patch, thanks
  David Matlack for pointing it out

all follow changes are from Paolo's comment and really appreciate it:
- reorder the whole patchset to make it is more readable
- redesign the iterator APIs
- make TLB clean if @lock_flush_tlb is true in slot_handle_level()
- make MTRR update be generic

This are some MTRR bugs if legacy IOMMU device is used on Intel's CPU:
- In current code, whenever guest MTRR registers are changed
  kvm_mmu_reset_context is called to switch to the new root shadow page
  table, however, it's useless since:
  1) the cache type is not cached into shadow page's attribute so that the
     original root shadow page will be reused

  2) the cache type is set on the last spte, that means we should sync the
     last sptes when MTRR is changed

  We can fix it by dropping all the spte in the gfn range which is
  being updated by MTRR

- some bugs are in get_mtrr_type();
  1: bit 1 of mtrr_state->enabled is corresponding bit 11 of IA32_MTRR_DEF_TYPE
     MSR which completely control MTRR's enablement that means other bits are
     ignored if it is cleared

  2: the fixed MTRR ranges are controlled by bit 0 of mtrr_state->enabled (bit
     10 of IA32_MTRR_DEF_TYPE)
  
  3: if MTRR is disabled, UC is applied to all of physical memory rather than
     mtrr_state->def_type

- we need not to reset mmu once cache policy is changed since shadow page table
  does not virtualize any cache policy

Also, these are some cleanups to make current MMU code more cleaner and help
us fixing the bug more easier. 

Xiao Guangrong (10):
  KVM: MMU: fix decoding cache type from MTRR
  KVM: MMU: introduce for_each_rmap_spte()
  KVM: MMU: introduce PT_MAX_HUGEPAGE_LEVEL
  KVM: MMU: introduce for_each_slot_rmap_range
  KVM: MMU: introduce slot_handle_level_range() and its helpers
  KVM: MMU: use slot_handle_level and its helper to clean  up the code
  KVM: MMU: introduce kvm_zap_rmapp
  KVM: MMU: introduce kvm_zap_gfn_range
  KVM: MMU: fix MTRR update
  KVM: x86: do not reset mmu if CR0.CD and CR0.NW are changed

 arch/x86/kvm/mmu.c       | 409 +++++++++++++++++++++++++----------------------
 arch/x86/kvm/mmu.h       |   2 +
 arch/x86/kvm/mmu_audit.c |   4 +-
 arch/x86/kvm/x86.c       |  62 ++++++-
 4 files changed, 281 insertions(+), 196 deletions(-)

-- 
2.1.0

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