KVM: MMU: coalesce more page zapping in mmu_sync_children

mmu_sync_children can only process up to 16 pages at a time.  Check
if we need to reschedule, and do not bother zapping the pages until
that happens.

Reviewed-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index fecc9c51d9240e1f62caf711ed3239a4ff416bab..754d2c4f6f99ec19abf9c6d05b53eee6201d1af8 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2059,24 +2059,31 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu,
        struct mmu_page_path parents;
        struct kvm_mmu_pages pages;
        LIST_HEAD(invalid_list);
+       bool flush = false;
 
        while (mmu_unsync_walk(parent, &pages)) {
                bool protected = false;
-               bool flush = false;
 
                for_each_sp(pages, sp, parents, i)
                        protected |= rmap_write_protect(vcpu, sp->gfn);
 
-               if (protected)
+               if (protected) {
                        kvm_flush_remote_tlbs(vcpu->kvm);
+                       flush = false;
+               }
 
                for_each_sp(pages, sp, parents, i) {
                        flush |= kvm_sync_page(vcpu, sp, &invalid_list);
                        mmu_pages_clear_parents(&parents);
                }
-               kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush);
-               cond_resched_lock(&vcpu->kvm->mmu_lock);
+               if (need_resched() || spin_needbreak(&vcpu->kvm->mmu_lock)) {
+                       kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush);
+                       cond_resched_lock(&vcpu->kvm->mmu_lock);
+                       flush = false;
+               }
        }
+
+       kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush);
 }
 
 static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp)