Commit 660c22c4 authored by Takuya Yoshikawa's avatar Takuya Yoshikawa Committed by Avi Kivity
Browse files

KVM: limit the number of pages per memory slot 



This patch limits the number of pages per memory slot to make
us free from extra care about type issues.

Signed-off-by: default avatarTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 020df079

include/linux/kvm_host.h

+6 −0
Original line number Diff line number Diff line
@@ -105,6 +105,12 @@ struct kvm_vcpu { 
	struct kvm_vcpu_arch arch;

};



/*

 * Some of the bitops functions do not support too long bitmaps.

 * This number must be determined not to exceed such limits.

 */

#define KVM_MEM_MAX_NR_PAGES ((1UL << 31) - 1)



struct kvm_memory_slot {

	gfn_t base_gfn;

	unsigned long npages;

virt/kvm/kvm_main.c

+6 −5
Original line number Diff line number Diff line
@@ -557,6 +557,10 @@ int __kvm_set_memory_region(struct kvm *kvm, 
	base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;

	npages = mem->memory_size >> PAGE_SHIFT;



	r = -EINVAL;

	if (npages > KVM_MEM_MAX_NR_PAGES)

		goto out;



	if (!npages)

		mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES;
@@ -1187,13 +1191,10 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn) 
	memslot = gfn_to_memslot_unaliased(kvm, gfn);

	if (memslot && memslot->dirty_bitmap) {

		unsigned long rel_gfn = gfn - memslot->base_gfn;

		unsigned long *p = memslot->dirty_bitmap +

					rel_gfn / BITS_PER_LONG;

		int offset = rel_gfn % BITS_PER_LONG;



		/* avoid RMW */

		if (!generic_test_le_bit(offset, p))

			generic___set_le_bit(offset, p);

		if (!generic_test_le_bit(rel_gfn, memslot->dirty_bitmap))

			generic___set_le_bit(rel_gfn, memslot->dirty_bitmap);

	}

}