The MMU always has hardware A bits or access tracking support, thus
it's unnecessary to handle the scenario where we have neither.
Signed-off-by: Peter Feiner <pfeiner@xxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 30 +++++++++---------------------
1 file changed, 9 insertions(+), 21 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 5d3376f67794..dfd4cd67e5a6 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -315,12 +315,21 @@ static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte)
return likely(kvm_gen == spte_gen);
}
+/*
+ * Sets the shadow PTE masks used by the MMU.
+ *
+ * Assumptions:
+ * - Setting either @accessed_mask or @dirty_mask requires setting both
+ * - At least one of @accessed_mask or @acc_track_mask must be set
+ */
void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask,
u64 dirty_mask, u64 nx_mask, u64 x_mask, u64 p_mask,
u64 acc_track_mask)
{
if (acc_track_mask != 0)
acc_track_mask |= SPTE_SPECIAL_MASK;
+ BUG_ON(!dirty_mask != !accessed_mask);
+ BUG_ON(!accessed_mask && !acc_track_mask);
shadow_user_mask = user_mask;
shadow_accessed_mask = accessed_mask;
@@ -1766,18 +1775,9 @@ static int kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
u64 *sptep;
struct rmap_iterator iter;
- /*
- * If there's no access bit in the secondary pte set by the hardware and
- * fast access tracking is also not enabled, it's up to gup-fast/gup to
- * set the access bit in the primary pte or in the page structure.
- */
- if (!shadow_accessed_mask && !shadow_acc_track_mask)
- goto out;
-
for_each_rmap_spte(rmap_head, &iter, sptep)
if (is_accessed_spte(*sptep))
return 1;
-out:
return 0;
}
@@ -1798,18 +1798,6 @@ static void rmap_recycle(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end)
{
- /*
- * In case of absence of EPT Access and Dirty Bits supports,
- * emulate the accessed bit for EPT, by checking if this page has
- * an EPT mapping, and clearing it if it does. On the next access,
- * a new EPT mapping will be established.
- * This has some overhead, but not as much as the cost of swapping
- * out actively used pages or breaking up actively used hugepages.
- */
- if (!shadow_accessed_mask && !shadow_acc_track_mask)
- return kvm_handle_hva_range(kvm, start, end, 0,
- kvm_unmap_rmapp);
-
return kvm_handle_hva_range(kvm, start, end, 0, kvm_age_rmapp);
}
--
2.13.2.725.g09c95d1e9-goog
