diff options
| author | Peter Feiner <pfeiner@google.com> | 2017-06-30 17:26:31 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2017-07-03 11:19:54 +0200 |
| commit | ac8d57e5734389da18633d4e8cc030fe10843da7 (patch) | |
| tree | cc5aec1dd7bd4f36366aa6a064f9970c1e77c20d /Documentation/virtual | |
| parent | dcdca5fed5f6ef2521f927ba3b5cd6b328054be1 (diff) | |
kvm: x86: mmu: allow A/D bits to be disabled in an mmu
Adds the plumbing to disable A/D bits in the MMU based on a new role
bit, ad_disabled. When A/D is disabled, the MMU operates as though A/D
aren't available (i.e., using access tracking faults instead).
To avoid SP -> kvm_mmu_page.role.ad_disabled lookups all over the
place, A/D disablement is now stored in the SPTE. This state is stored
in the SPTE by tweaking the use of SPTE_SPECIAL_MASK for access
tracking. Rather than just setting SPTE_SPECIAL_MASK when an
access-tracking SPTE is non-present, we now always set
SPTE_SPECIAL_MASK for access-tracking SPTEs.
Signed-off-by: Peter Feiner <pfeiner@google.com>
[Use role.ad_disabled even for direct (non-shadow) EPT page tables. Add
documentation and a few MMU_WARN_ONs. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virtual')
| -rw-r--r-- | Documentation/virtual/kvm/mmu.txt | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt index 481b6a9c25d5..f50d45b1e967 100644 --- a/Documentation/virtual/kvm/mmu.txt +++ b/Documentation/virtual/kvm/mmu.txt @@ -179,6 +179,10 @@ Shadow pages contain the following information: shadow page; it is also used to go back from a struct kvm_mmu_page to a memslot, through the kvm_memslots_for_spte_role macro and __gfn_to_memslot. + role.ad_disabled: + Is 1 if the MMU instance cannot use A/D bits. EPT did not have A/D + bits before Haswell; shadow EPT page tables also cannot use A/D bits + if the L1 hypervisor does not enable them. gfn: Either the guest page table containing the translations shadowed by this page, or the base page frame for linear translations. See role.direct. |