Commit f0877a14 authored by Will Deacon's avatar Will Deacon Committed by Marc Zyngier
Browse files

KVM: arm64: Prevent unsupported memslot operations on protected VMs 



Protected VMs do not support deleting or moving memslots after first
run nor do they support read-only or dirty logging.

Return -EPERM to userspace if such an operation is attempted.

Reviewed-by: default avatarFuad Tabba <tabba@google.com>
Tested-by: default avatarFuad Tabba <tabba@google.com>
Tested-by: default avatarMostafa Saleh <smostafa@google.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Link: https://patch.msgid.link/20260330144841.26181-10-will@kernel.org


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 7250533a

arch/arm64/kvm/mmu.c

+13 −0
Original line number Diff line number Diff line
@@ -2414,6 +2414,19 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, 
	hva_t hva, reg_end;

	int ret = 0;



	if (kvm_vm_is_protected(kvm)) {

		/* Cannot modify memslots once a pVM has run. */

		if (pkvm_hyp_vm_is_created(kvm) &&

		    (change == KVM_MR_DELETE || change == KVM_MR_MOVE)) {

			return -EPERM;

		}



		if (new &&

		    new->flags & (KVM_MEM_LOG_DIRTY_PAGES | KVM_MEM_READONLY)) {

			return -EPERM;

		}

	}



	if (change != KVM_MR_CREATE && change != KVM_MR_MOVE &&

			change != KVM_MR_FLAGS_ONLY)

		return 0;

arch/arm64/kvm/pkvm.c

+6 −0
Original line number Diff line number Diff line
@@ -192,10 +192,16 @@ int pkvm_create_hyp_vm(struct kvm *kvm) 
{

	int ret = 0;



	/*

	 * Synchronise with kvm_arch_prepare_memory_region(), as we

	 * prevent memslot modifications on a pVM that has been run.

	 */

	mutex_lock(&kvm->slots_lock);

	mutex_lock(&kvm->arch.config_lock);

	if (!pkvm_hyp_vm_is_created(kvm))

		ret = __pkvm_create_hyp_vm(kvm);

	mutex_unlock(&kvm->arch.config_lock);

	mutex_unlock(&kvm->slots_lock);



	return ret;

}