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Commit 4bd518f1 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: use separate generations for each address space 



This will make it easier to support multiple address spaces in
kvm_gfn_to_hva_cache_init.  Instead of having to check the address
space id, we can keep on checking just the generation number.

Reviewed-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 5a2d4365

virt/kvm/kvm_main.c

+16 −8
Original line number Diff line number Diff line
@@ -506,11 +506,6 @@ static struct kvm_memslots *kvm_alloc_memslots(void) 
	if (!slots)

		return NULL;



	/*

	 * Init kvm generation close to the maximum to easily test the

	 * code of handling generation number wrap-around.

	 */

	slots->generation = -150;

	for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)

		slots->id_to_index[i] = slots->memslots[i].id = i;
@@ -641,9 +636,16 @@ static struct kvm *kvm_create_vm(unsigned long type) 


	r = -ENOMEM;

	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {

		kvm->memslots[i] = kvm_alloc_memslots();

		if (!kvm->memslots[i])

		struct kvm_memslots *slots = kvm_alloc_memslots();

		if (!slots)

			goto out_err_no_srcu;

		/*

		 * Generations must be different for each address space.

		 * Init kvm generation close to the maximum to easily test the

		 * code of handling generation number wrap-around.

		 */

		slots->generation = i * 2 - 150;

		rcu_assign_pointer(kvm->memslots[i], slots);

	}



	if (init_srcu_struct(&kvm->srcu))
@@ -870,8 +872,14 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm, 
	 * Increment the new memslot generation a second time. This prevents

	 * vm exits that race with memslot updates from caching a memslot

	 * generation that will (potentially) be valid forever.

	 *

	 * Generations must be unique even across address spaces.  We do not need

	 * a global counter for that, instead the generation space is evenly split

	 * across address spaces.  For example, with two address spaces, address

	 * space 0 will use generations 0, 4, 8, ... while * address space 1 will

	 * use generations 2, 6, 10, 14, ...

	 */

	slots->generation++;

	slots->generation += KVM_ADDRESS_SPACE_NUM * 2 - 1;



	kvm_arch_memslots_updated(kvm, slots);