diff options
| author | Ben Gardon <bgardon@google.com> | 2020-10-14 11:27:00 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-10-23 03:42:16 -0400 |
| commit | 29cf0f5007a215b51feb0ae25ca5353480d53ead (patch) | |
| tree | 9bfe41f21e77b1dc5ad71f7946ce6f76f5fb773a /arch/x86/kvm/mmu/tdp_mmu.c | |
| parent | daa5b6c12337a0e6e269d022baa21b0549f507c3 (diff) | |
kvm: x86/mmu: NX largepage recovery for TDP MMU
When KVM maps a largepage backed region at a lower level in order to
make it executable (i.e. NX large page shattering), it reduces the TLB
performance of that region. In order to avoid making this degradation
permanent, KVM must periodically reclaim shattered NX largepages by
zapping them and allowing them to be rebuilt in the page fault handler.
With this patch, the TDP MMU does not respect KVM's rate limiting on
reclaim. It traverses the entire TDP structure every time. This will be
addressed in a future patch.
Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.
This series can be viewed in Gerrit at:
https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20201014182700.2888246-21-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/mmu/tdp_mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 5158d02b8925..e246d71b8ea2 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -273,6 +273,9 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, list_del(&sp->link); + if (sp->lpage_disallowed) + unaccount_huge_nx_page(kvm, sp); + for (i = 0; i < PT64_ENT_PER_PAGE; i++) { old_child_spte = READ_ONCE(*(pt + i)); WRITE_ONCE(*(pt + i), 0); @@ -571,6 +574,9 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, !shadow_accessed_mask); trace_kvm_mmu_get_page(sp, true); + if (huge_page_disallowed && req_level >= iter.level) + account_huge_nx_page(vcpu->kvm, sp); + tdp_mmu_set_spte(vcpu->kvm, &iter, new_spte); } } |