3 files changed, 40 insertions, 15 deletions

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 161a9e12bfb8..d681ae462350 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -798,14 +798,12 @@ struct kvm_s390_cpu_model {
 	unsigned short ibc;
 };
 
-struct kvm_s390_module_hook {
-	int (*hook)(struct kvm_vcpu *vcpu);
-	struct module *owner;
-};
+typedef int (*crypto_hook)(struct kvm_vcpu *vcpu);
 
 struct kvm_s390_crypto {
 	struct kvm_s390_crypto_cb *crycb;
-	struct kvm_s390_module_hook *pqap_hook;
+	struct rw_semaphore pqap_hook_rwsem;
+	crypto_hook *pqap_hook;
 	__u32 crycbd;
 	__u8 aes_kw;
 	__u8 dea_kw;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 4527ac7b5961..efda0615741f 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2559,12 +2559,26 @@ static void kvm_s390_set_crycb_format(struct kvm *kvm)
 		kvm->arch.crypto.crycbd |= CRYCB_FORMAT1;
 }
 
+/*
+ * kvm_arch_crypto_set_masks
+ *
+ * @kvm: pointer to the target guest's KVM struct containing the crypto masks
+ *	 to be set.
+ * @apm: the mask identifying the accessible AP adapters
+ * @aqm: the mask identifying the accessible AP domains
+ * @adm: the mask identifying the accessible AP control domains
+ *
+ * Set the masks that identify the adapters, domains and control domains to
+ * which the KVM guest is granted access.
+ *
+ * Note: The kvm->lock mutex must be locked by the caller before invoking this
+ *	 function.
+ */
 void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm,
 			       unsigned long *aqm, unsigned long *adm)
 {
 	struct kvm_s390_crypto_cb *crycb = kvm->arch.crypto.crycb;
 
-	mutex_lock(&kvm->lock);
 	kvm_s390_vcpu_block_all(kvm);
 
 	switch (kvm->arch.crypto.crycbd & CRYCB_FORMAT_MASK) {
@@ -2595,13 +2609,23 @@ void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm,
 	/* recreate the shadow crycb for each vcpu */
 	kvm_s390_sync_request_broadcast(kvm, KVM_REQ_VSIE_RESTART);
 	kvm_s390_vcpu_unblock_all(kvm);
-	mutex_unlock(&kvm->lock);
 }
 EXPORT_SYMBOL_GPL(kvm_arch_crypto_set_masks);
 
+/*
+ * kvm_arch_crypto_clear_masks
+ *
+ * @kvm: pointer to the target guest's KVM struct containing the crypto masks
+ *	 to be cleared.
+ *
+ * Clear the masks that identify the adapters, domains and control domains to
+ * which the KVM guest is granted access.
+ *
+ * Note: The kvm->lock mutex must be locked by the caller before invoking this
+ *	 function.
+ */
 void kvm_arch_crypto_clear_masks(struct kvm *kvm)
 {
-	mutex_lock(&kvm->lock);
 	kvm_s390_vcpu_block_all(kvm);
 
 	memset(&kvm->arch.crypto.crycb->apcb0, 0,
@@ -2613,7 +2637,6 @@ void kvm_arch_crypto_clear_masks(struct kvm *kvm)
 	/* recreate the shadow crycb for each vcpu */
 	kvm_s390_sync_request_broadcast(kvm, KVM_REQ_VSIE_RESTART);
 	kvm_s390_vcpu_unblock_all(kvm);
-	mutex_unlock(&kvm->lock);
 }
 EXPORT_SYMBOL_GPL(kvm_arch_crypto_clear_masks);
 
@@ -2630,6 +2653,7 @@ static void kvm_s390_crypto_init(struct kvm *kvm)
 {
 	kvm->arch.crypto.crycb = &kvm->arch.sie_page2->crycb;
 	kvm_s390_set_crycb_format(kvm);
+	init_rwsem(&kvm->arch.crypto.pqap_hook_rwsem);
 
 	if (!test_kvm_facility(kvm, 76))
 		return;
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 9928f785c677..53da4ceb16a3 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -610,6 +610,7 @@ static int handle_io_inst(struct kvm_vcpu *vcpu)
 static int handle_pqap(struct kvm_vcpu *vcpu)
 {
 	struct ap_queue_status status = {};
+	crypto_hook pqap_hook;
 	unsigned long reg0;
 	int ret;
 	uint8_t fc;
@@ -654,18 +655,20 @@ static int handle_pqap(struct kvm_vcpu *vcpu)
 		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 
 	/*
-	 * Verify that the hook callback is registered, lock the owner
-	 * and call the hook.
+	 * If the hook callback is registered, there will be a pointer to the
+	 * hook function pointer in the kvm_s390_crypto structure. Lock the
+	 * owner, retrieve the hook function pointer and call the hook.
 	 */
+	down_read(&vcpu->kvm->arch.crypto.pqap_hook_rwsem);
 	if (vcpu->kvm->arch.crypto.pqap_hook) {
-		if (!try_module_get(vcpu->kvm->arch.crypto.pqap_hook->owner))
-			return -EOPNOTSUPP;
-		ret = vcpu->kvm->arch.crypto.pqap_hook->hook(vcpu);
-		module_put(vcpu->kvm->arch.crypto.pqap_hook->owner);
+		pqap_hook = *vcpu->kvm->arch.crypto.pqap_hook;
+		ret = pqap_hook(vcpu);
 		if (!ret && vcpu->run->s.regs.gprs[1] & 0x00ff0000)
 			kvm_s390_set_psw_cc(vcpu, 3);
+		up_read(&vcpu->kvm->arch.crypto.pqap_hook_rwsem);
 		return ret;
 	}
+	up_read(&vcpu->kvm->arch.crypto.pqap_hook_rwsem);
 	/*
 	 * A vfio_driver must register a hook.
 	 * No hook means no driver to enable the SIE CRYCB and no queues.