Commit d13bc5b5 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Avi Kivity
Browse files

KVM: MMU: abstract spte write-protect 



Introduce a common function to abstract spte write-protect to
cleanup the code

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 2f84569f

arch/x86/kvm/mmu.c

+31 −27
Original line number Diff line number Diff line
@@ -1050,36 +1050,48 @@ static void drop_spte(struct kvm *kvm, u64 *sptep) 
		rmap_remove(kvm, sptep);

}



/* Return true if the spte is dropped. */

static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool *flush)

{

	u64 spte = *sptep;



	if (!is_writable_pte(spte))

		return false;



	rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);



	*flush |= true;

	if (is_large_pte(spte)) {

		WARN_ON(page_header(__pa(sptep))->role.level ==

		       PT_PAGE_TABLE_LEVEL);

		drop_spte(kvm, sptep);

		--kvm->stat.lpages;

		return true;

	}



	spte = spte & ~PT_WRITABLE_MASK;

	mmu_spte_update(sptep, spte);

	return false;

}



static bool

__rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, int level)

{

	u64 *sptep;

	struct rmap_iterator iter;

	bool write_protected = false;

	bool flush = false;



	for (sptep = rmap_get_first(*rmapp, &iter); sptep;) {

		BUG_ON(!(*sptep & PT_PRESENT_MASK));

		rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);



		if (!is_writable_pte(*sptep)) {

			sptep = rmap_get_next(&iter);

		if (spte_write_protect(kvm, sptep, &flush)) {

			sptep = rmap_get_first(*rmapp, &iter);

			continue;

		}



		if (level == PT_PAGE_TABLE_LEVEL) {

			mmu_spte_update(sptep, *sptep & ~PT_WRITABLE_MASK);

		sptep = rmap_get_next(&iter);

		} else {

			BUG_ON(!is_large_pte(*sptep));

			drop_spte(kvm, sptep);

			--kvm->stat.lpages;

			sptep = rmap_get_first(*rmapp, &iter);

	}



		write_protected = true;

	}



	return write_protected;

	return flush;

}



/**
@@ -3886,6 +3898,7 @@ int kvm_mmu_setup(struct kvm_vcpu *vcpu) 
void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)

{

	struct kvm_mmu_page *sp;

	bool flush = false;



	list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link) {

		int i;
@@ -3900,16 +3913,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) 
			      !is_last_spte(pt[i], sp->role.level))

				continue;



			if (is_large_pte(pt[i])) {

				drop_spte(kvm, &pt[i]);

				--kvm->stat.lpages;

				continue;

			}



			/* avoid RMW */

			if (is_writable_pte(pt[i]))

				mmu_spte_update(&pt[i],

						pt[i] & ~PT_WRITABLE_MASK);

			spte_write_protect(kvm, &pt[i], &flush);

		}

	}

	kvm_flush_remote_tlbs(kvm);