Re: [PATCH v3 8/8] KVM: x86/mmu: Lazily allocate memslot rmaps

From: Paolo Bonzini
Date: Fri May 07 2021 - 04:29:00 EST


On 06/05/21 20:42, Ben Gardon wrote:
+ /*
+ * memslots_have_rmaps is set and read in different lock contexts,
+ * so protect it with smp_load/store.
+ */
+ smp_store_release(&kvm->arch.memslots_have_rmaps, true);

Shorter and better: /* write rmap pointers before memslots_have_rmaps */

+ mutex_unlock(&kvm->slots_arch_lock);
+ return 0;
+}
+
bool kvm_memslots_have_rmaps(struct kvm *kvm)
{
- return kvm->arch.memslots_have_rmaps;
+ /*
+ * memslots_have_rmaps is set and read in different lock contexts,
+ * so protect it with smp_load/store.
+ */
+ return smp_load_acquire(&kvm->arch.memslots_have_rmaps);
}

Likewise, /* read memslots_have_rmaps before the rmaps themselves */

Paolo