KVM: x86/mmu: Zap only the relevant pages when removing a memslot (4e103134) · Commits · 戴 / test

Modify kvm_mmu_invalidate_zap_pages_in_memslot(), a.k.a. the x86 MMU's handler for kvm_arch_flush_shadow_memslot(), to zap only the pages/PTEs that actually belong to the memslot being removed. This improves performance, especially why the deleted memslot has only a few shadow entries, or even no entries. E.g. a microbenchmark to access regular memory while concurrently reading PCI ROM to trigger memslot deletion showed a 5% improvement in throughput. Cc: Xiao Guangrong <guangrong.xiao@gmail.com> Signed-off-by:

Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.c

+32 −1

Original line number	Diff line number	Diff line
		@@ -5622,7 +5622,38 @@ static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm,
		struct kvm_memory_slot *slot,
		struct kvm_page_track_notifier_node *node)
		{
		kvm_mmu_invalidate_zap_all_pages(kvm);
		struct kvm_mmu_page *sp;
		LIST_HEAD(invalid_list);
		unsigned long i;
		bool flush;
		gfn_t gfn;

		spin_lock(&kvm->mmu_lock);

		if (list_empty(&kvm->arch.active_mmu_pages))
		goto out_unlock;

		flush = slot_handle_all_level(kvm, slot, kvm_zap_rmapp, false);

		for (i = 0; i < slot->npages; i++) {
		gfn = slot->base_gfn + i;

		for_each_valid_sp(kvm, sp, gfn) {
		if (sp->gfn != gfn)
		continue;

		kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
		}
		if (need_resched() \|\| spin_needbreak(&kvm->mmu_lock)) {
		kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush);
		flush = false;
		cond_resched_lock(&kvm->mmu_lock);
		}
		}
		kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush);

		out_unlock:
		spin_unlock(&kvm->mmu_lock);
		}

		void kvm_mmu_init_vm(struct kvm *kvm)

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