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.
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
virt/kvm/kvm_main.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e21bac7ed5d3..a83c186cefc1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -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);
--
1.8.3.1
