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Commit d91ffee9 authored by Kai Huang's avatar Kai Huang Committed by Paolo Bonzini
Browse files

Optimize TLB flush in kvm_mmu_slot_remove_write_access. 



No TLB flush is needed when there's no valid rmap in memory slot.

Signed-off-by: default avatarKai Huang <kai.huang@linux.intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0c55d6d9

arch/x86/kvm/mmu.c

+5 −2
Original line number Diff line number Diff line
@@ -4302,6 +4302,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) 
	struct kvm_memory_slot *memslot;

	gfn_t last_gfn;

	int i;

	bool flush = false;



	memslot = id_to_memslot(kvm->memslots, slot);

	last_gfn = memslot->base_gfn + memslot->npages - 1;
@@ -4318,7 +4319,8 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) 


		for (index = 0; index <= last_index; ++index, ++rmapp) {

			if (*rmapp)

				__rmap_write_protect(kvm, rmapp, false);

				flush |= __rmap_write_protect(kvm, rmapp,

						false);



			if (need_resched() || spin_needbreak(&kvm->mmu_lock))

				cond_resched_lock(&kvm->mmu_lock);
@@ -4345,6 +4347,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) 
	 * instead of PT_WRITABLE_MASK, that means it does not depend

	 * on PT_WRITABLE_MASK anymore.

	 */

	if (flush)

		kvm_flush_remote_tlbs(kvm);

}