Commit a0ed4607 authored by Takuya Yoshikawa's avatar Takuya Yoshikawa Committed by Avi Kivity
Browse files

KVM: MMU: Split the main body of rmap_write_protect() off from others 



We will use this in the following patch to implement another function
which needs to write protect pages using the rmap information.

Note that there is a small change in debug printing for large pages:
we do not differentiate them from others to avoid duplicating code.

Signed-off-by: default avatarTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 24899709

arch/x86/kvm/mmu.c

+27 −26
Original line number Diff line number Diff line
@@ -1010,42 +1010,43 @@ static void drop_spte(struct kvm *kvm, u64 *sptep) 
		rmap_remove(kvm, sptep);

}



int kvm_mmu_rmap_write_protect(struct kvm *kvm, u64 gfn,

			       struct kvm_memory_slot *slot)

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

{

	unsigned long *rmapp;

	u64 *spte;

	int i, write_protected = 0;

	u64 *spte = NULL;

	int write_protected = 0;



	rmapp = __gfn_to_rmap(gfn, PT_PAGE_TABLE_LEVEL, slot);

	spte = rmap_next(rmapp, NULL);

	while (spte) {

	while ((spte = rmap_next(rmapp, spte))) {

		BUG_ON(!(*spte & PT_PRESENT_MASK));

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

		if (is_writable_pte(*spte)) {

			mmu_spte_update(spte, *spte & ~PT_WRITABLE_MASK);

			write_protected = 1;

		}

		spte = rmap_next(rmapp, spte);

	}



	/* check for huge page mappings */

	for (i = PT_DIRECTORY_LEVEL;

	     i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {

		rmapp = __gfn_to_rmap(gfn, i, slot);

		spte = rmap_next(rmapp, NULL);

		while (spte) {

			BUG_ON(!(*spte & PT_PRESENT_MASK));

		if (!is_writable_pte(*spte))

			continue;



		if (level == PT_PAGE_TABLE_LEVEL) {

			mmu_spte_update(spte, *spte & ~PT_WRITABLE_MASK);

		} else {

			BUG_ON(!is_large_pte(*spte));

			pgprintk("rmap_write_protect(large): spte %p %llx %lld\n", spte, *spte, gfn);

			if (is_writable_pte(*spte)) {

			drop_spte(kvm, spte);

			--kvm->stat.lpages;

			spte = NULL;

		}



		write_protected = 1;

	}

			spte = rmap_next(rmapp, spte);



	return write_protected;

}



int kvm_mmu_rmap_write_protect(struct kvm *kvm, u64 gfn,

			       struct kvm_memory_slot *slot)

{

	unsigned long *rmapp;

	int i, write_protected = 0;



	for (i = PT_PAGE_TABLE_LEVEL;

	     i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {

		rmapp = __gfn_to_rmap(gfn, i, slot);

		write_protected |= __rmap_write_protect(kvm, rmapp, i);

	}



	return write_protected;