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Commit b1a36821 authored by Marcelo Tosatti's avatar Marcelo Tosatti Committed by Avi Kivity
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KVM: MMU: collapse remote TLB flushes on root sync 



Collapse remote TLB flushes on root sync.

kernbench is 2.7% faster on 4-way guest. Improvements have been seen
with other loads such as AIM7.

Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 60c8aec6

arch/x86/kvm/mmu.c

+14 −5
Original line number Diff line number Diff line
@@ -621,7 +621,7 @@ static u64 *rmap_next(struct kvm *kvm, unsigned long *rmapp, u64 *spte) 
	return NULL;

}



static void rmap_write_protect(struct kvm *kvm, u64 gfn)

static int rmap_write_protect(struct kvm *kvm, u64 gfn)

{

	unsigned long *rmapp;

	u64 *spte;
@@ -667,8 +667,7 @@ static void rmap_write_protect(struct kvm *kvm, u64 gfn) 
		spte = rmap_next(kvm, rmapp, spte);

	}



	if (write_protected)

		kvm_flush_remote_tlbs(kvm);

	return write_protected;

}



static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp)
@@ -1083,7 +1082,8 @@ static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) 
		return 1;

	}



	rmap_write_protect(vcpu->kvm, sp->gfn);

	if (rmap_write_protect(vcpu->kvm, sp->gfn))

		kvm_flush_remote_tlbs(vcpu->kvm);

	kvm_unlink_unsync_page(vcpu->kvm, sp);

	if (vcpu->arch.mmu.sync_page(vcpu, sp)) {

		kvm_mmu_zap_page(vcpu->kvm, sp);
@@ -1162,6 +1162,14 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu, 


	kvm_mmu_pages_init(parent, &parents, &pages);

	while (mmu_unsync_walk(parent, &pages)) {

		int protected = 0;



		for_each_sp(pages, sp, parents, i)

			protected |= rmap_write_protect(vcpu->kvm, sp->gfn);



		if (protected)

			kvm_flush_remote_tlbs(vcpu->kvm);



		for_each_sp(pages, sp, parents, i) {

			kvm_sync_page(vcpu, sp);

			mmu_pages_clear_parents(&parents);
@@ -1226,7 +1234,8 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, 
	sp->role = role;

	hlist_add_head(&sp->hash_link, bucket);

	if (!metaphysical) {

		rmap_write_protect(vcpu->kvm, gfn);

		if (rmap_write_protect(vcpu->kvm, gfn))

			kvm_flush_remote_tlbs(vcpu->kvm);

		account_shadowed(vcpu->kvm, gfn);

	}

	if (shadow_trap_nonpresent_pte != shadow_notrap_nonpresent_pte)