KVM: MMU: speed up mmu_unsync_walk
Cache the unsynced children information in a per-page bitmap.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index d88659a..cb391d6 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -891,6 +891,52 @@
}
}
+static void kvm_mmu_update_unsync_bitmap(u64 *spte)
+{
+ unsigned int index;
+ struct kvm_mmu_page *sp = page_header(__pa(spte));
+
+ index = spte - sp->spt;
+ __set_bit(index, sp->unsync_child_bitmap);
+ sp->unsync_children = 1;
+}
+
+static void kvm_mmu_update_parents_unsync(struct kvm_mmu_page *sp)
+{
+ struct kvm_pte_chain *pte_chain;
+ struct hlist_node *node;
+ int i;
+
+ if (!sp->parent_pte)
+ return;
+
+ if (!sp->multimapped) {
+ kvm_mmu_update_unsync_bitmap(sp->parent_pte);
+ return;
+ }
+
+ hlist_for_each_entry(pte_chain, node, &sp->parent_ptes, link)
+ for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) {
+ if (!pte_chain->parent_ptes[i])
+ break;
+ kvm_mmu_update_unsync_bitmap(pte_chain->parent_ptes[i]);
+ }
+}
+
+static int unsync_walk_fn(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
+{
+ sp->unsync_children = 1;
+ kvm_mmu_update_parents_unsync(sp);
+ return 1;
+}
+
+static void kvm_mmu_mark_parents_unsync(struct kvm_vcpu *vcpu,
+ struct kvm_mmu_page *sp)
+{
+ mmu_parent_walk(vcpu, sp, unsync_walk_fn);
+ kvm_mmu_update_parents_unsync(sp);
+}
+
static void nonpaging_prefetch_page(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp)
{
@@ -910,6 +956,11 @@
{
}
+#define for_each_unsync_children(bitmap, idx) \
+ for (idx = find_first_bit(bitmap, 512); \
+ idx < 512; \
+ idx = find_next_bit(bitmap, 512, idx+1))
+
static int mmu_unsync_walk(struct kvm_mmu_page *sp,
struct kvm_unsync_walk *walker)
{
@@ -918,7 +969,7 @@
if (!sp->unsync_children)
return 0;
- for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
+ for_each_unsync_children(sp->unsync_child_bitmap, i) {
u64 ent = sp->spt[i];
if (is_shadow_present_pte(ent)) {
@@ -929,17 +980,19 @@
ret = mmu_unsync_walk(child, walker);
if (ret)
return ret;
+ __clear_bit(i, sp->unsync_child_bitmap);
}
if (child->unsync) {
ret = walker->entry(child, walker);
+ __clear_bit(i, sp->unsync_child_bitmap);
if (ret)
return ret;
}
}
}
- if (i == PT64_ENT_PER_PAGE)
+ if (find_first_bit(sp->unsync_child_bitmap, 512) == 512)
sp->unsync_children = 0;
return 0;
@@ -1056,10 +1109,11 @@
if (sp->role.word != role.word)
continue;
- if (sp->unsync_children)
- set_bit(KVM_REQ_MMU_SYNC, &vcpu->requests);
-
mmu_page_add_parent_pte(vcpu, sp, parent_pte);
+ if (sp->unsync_children) {
+ set_bit(KVM_REQ_MMU_SYNC, &vcpu->requests);
+ kvm_mmu_mark_parents_unsync(vcpu, sp);
+ }
pgprintk("%s: found\n", __func__);
return sp;
}
@@ -1336,12 +1390,6 @@
return page;
}
-static int unsync_walk_fn(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
-{
- sp->unsync_children = 1;
- return 1;
-}
-
static int kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
{
unsigned index;
@@ -1358,7 +1406,7 @@
if (s->role.word != sp->role.word)
return 1;
}
- mmu_parent_walk(vcpu, sp, unsync_walk_fn);
+ kvm_mmu_mark_parents_unsync(vcpu, sp);
++vcpu->kvm->stat.mmu_unsync;
sp->unsync = 1;
mmu_convert_notrap(sp);
