diff options
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/Kconfig | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 10 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 36 |
4 files changed, 35 insertions, 13 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index b15cde0a9b5c..5a07bdcc3e4f 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1478,6 +1478,7 @@ struct kvm_arch { * tdp_mmu_page set. * * For reads, this list is protected by: + * RCU alone or * the MMU lock in read mode + RCU or * the MMU lock in write mode * diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index ea2c4f21c1ca..fe8ea8c097de 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -22,6 +22,7 @@ config KVM_X86 select KVM_COMMON select KVM_GENERIC_MMU_NOTIFIER select KVM_ELIDE_TLB_FLUSH_IF_YOUNG + select KVM_MMU_LOCKLESS_AGING select HAVE_KVM_IRQCHIP select HAVE_KVM_PFNCACHE select HAVE_KVM_DIRTY_RING_TSO diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 5b9ef3535f50..b73b3c12f76f 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -1592,8 +1592,11 @@ bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { bool young = false; - if (kvm_memslots_have_rmaps(kvm)) + if (kvm_memslots_have_rmaps(kvm)) { + write_lock(&kvm->mmu_lock); young = kvm_rmap_age_gfn_range(kvm, range, false); + write_unlock(&kvm->mmu_lock); + } if (tdp_mmu_enabled) young |= kvm_tdp_mmu_age_gfn_range(kvm, range); @@ -1605,8 +1608,11 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { bool young = false; - if (kvm_memslots_have_rmaps(kvm)) + if (kvm_memslots_have_rmaps(kvm)) { + write_lock(&kvm->mmu_lock); young = kvm_rmap_age_gfn_range(kvm, range, true); + write_unlock(&kvm->mmu_lock); + } if (tdp_mmu_enabled) young |= kvm_tdp_mmu_test_age_gfn(kvm, range); diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 046b6ba31197..c9778c3e6ecd 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -193,6 +193,19 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, !tdp_mmu_root_match((_root), (_types)))) { \ } else +/* + * Iterate over all TDP MMU roots in an RCU read-side critical section. + * It is safe to iterate over the SPTEs under the root, but their values will + * be unstable, so all writes must be atomic. As this routine is meant to be + * used without holding the mmu_lock at all, any bits that are flipped must + * be reflected in kvm_tdp_mmu_spte_need_atomic_write(). + */ +#define for_each_tdp_mmu_root_rcu(_kvm, _root, _as_id, _types) \ + list_for_each_entry_rcu(_root, &_kvm->arch.tdp_mmu_roots, link) \ + if ((_as_id >= 0 && kvm_mmu_page_as_id(_root) != _as_id) || \ + !tdp_mmu_root_match((_root), (_types))) { \ + } else + #define for_each_valid_tdp_mmu_root(_kvm, _root, _as_id) \ __for_each_tdp_mmu_root(_kvm, _root, _as_id, KVM_VALID_ROOTS) @@ -1332,21 +1345,22 @@ bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range, * from the clear_young() or clear_flush_young() notifier, which uses the * return value to determine if the page has been accessed. */ -static void kvm_tdp_mmu_age_spte(struct tdp_iter *iter) +static void kvm_tdp_mmu_age_spte(struct kvm *kvm, struct tdp_iter *iter) { u64 new_spte; if (spte_ad_enabled(iter->old_spte)) { - iter->old_spte = tdp_mmu_clear_spte_bits(iter->sptep, - iter->old_spte, - shadow_accessed_mask, - iter->level); + iter->old_spte = tdp_mmu_clear_spte_bits_atomic(iter->sptep, + shadow_accessed_mask); new_spte = iter->old_spte & ~shadow_accessed_mask; } else { new_spte = mark_spte_for_access_track(iter->old_spte); - iter->old_spte = kvm_tdp_mmu_write_spte(iter->sptep, - iter->old_spte, new_spte, - iter->level); + /* + * It is safe for the following cmpxchg to fail. Leave the + * Accessed bit set, as the spte is most likely young anyway. + */ + if (__tdp_mmu_set_spte_atomic(kvm, iter, new_spte)) + return; } trace_kvm_tdp_mmu_spte_changed(iter->as_id, iter->gfn, iter->level, @@ -1371,9 +1385,9 @@ static bool __kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, * valid roots! */ WARN_ON(types & ~KVM_VALID_ROOTS); - __for_each_tdp_mmu_root(kvm, root, range->slot->as_id, types) { - guard(rcu)(); + guard(rcu)(); + for_each_tdp_mmu_root_rcu(kvm, root, range->slot->as_id, types) { tdp_root_for_each_leaf_pte(iter, kvm, root, range->start, range->end) { if (!is_accessed_spte(iter.old_spte)) continue; @@ -1382,7 +1396,7 @@ static bool __kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, return true; ret = true; - kvm_tdp_mmu_age_spte(&iter); + kvm_tdp_mmu_age_spte(kvm, &iter); } } |