KVM: x86/mmu: Revert "KVM: x86/mmu: Remove is_obsolete() call"
Now that the fast invalidate mechanism has been reintroduced, restore
the performance tweaks for fast invalidation that existed prior to its
removal.
Paraphrasing the original changelog (commit 5ff0568374ed2 was itself a
partial revert):
Don't force reloading the remote mmu when zapping an obsolete page, as
a MMU_RELOAD request has already been issued by kvm_mmu_zap_all_fast()
immediately after incrementing mmu_valid_gen, i.e. after marking pages
obsolete.
This reverts commit 5ff0568374ed2e585376a3832857ade5daccd381.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 652f2ce..e552fd5 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2752,7 +2752,12 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm,
} else {
list_move(&sp->link, &kvm->arch.active_mmu_pages);
- if (!sp->role.invalid)
+ /*
+ * Obsolete pages cannot be used on any vCPUs, see the comment
+ * in kvm_mmu_zap_all_fast(). Note, is_obsolete_sp() also
+ * treats invalid shadow pages as being obsolete.
+ */
+ if (!is_obsolete_sp(kvm, sp))
kvm_reload_remote_mmus(kvm);
}
@@ -5675,7 +5680,6 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
static void kvm_zap_obsolete_pages(struct kvm *kvm)
{
struct kvm_mmu_page *sp, *node;
- LIST_HEAD(invalid_list);
int nr_zapped, batch = 0;
restart:
@@ -5708,8 +5712,8 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm)
goto restart;
}
- if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list,
- &nr_zapped)) {
+ if (__kvm_mmu_prepare_zap_page(kvm, sp,
+ &kvm->arch.zapped_obsolete_pages, &nr_zapped)) {
batch += nr_zapped;
goto restart;
}
@@ -5720,7 +5724,7 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm)
* KVM is not in the middle of a lockless shadow page table walk, which
* may reference the pages.
*/
- kvm_mmu_commit_zap_page(kvm, &invalid_list);
+ kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages);
}
/*
@@ -5752,6 +5756,11 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm)
spin_unlock(&kvm->mmu_lock);
}
+static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm)
+{
+ return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages));
+}
+
static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm,
struct kvm_memory_slot *slot,
struct kvm_page_track_notifier_node *node)
@@ -6022,16 +6031,24 @@ mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
* want to shrink a VM that only started to populate its MMU
* anyway.
*/
- if (!kvm->arch.n_used_mmu_pages)
+ if (!kvm->arch.n_used_mmu_pages &&
+ !kvm_has_zapped_obsolete_pages(kvm))
continue;
idx = srcu_read_lock(&kvm->srcu);
spin_lock(&kvm->mmu_lock);
+ if (kvm_has_zapped_obsolete_pages(kvm)) {
+ kvm_mmu_commit_zap_page(kvm,
+ &kvm->arch.zapped_obsolete_pages);
+ goto unlock;
+ }
+
if (prepare_zap_oldest_mmu_page(kvm, &invalid_list))
freed++;
kvm_mmu_commit_zap_page(kvm, &invalid_list);
+unlock:
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 977b363..c9a3d8e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9425,6 +9425,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
INIT_HLIST_HEAD(&kvm->arch.mask_notifier_list);
INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
+ INIT_LIST_HEAD(&kvm->arch.zapped_obsolete_pages);
INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);
atomic_set(&kvm->arch.noncoherent_dma_count, 0);