KVM: s390: pv: support for Destroy fast UVC

Add support for the Destroy Secure Configuration Fast Ultravisor call,
and take advantage of it for asynchronous destroy.

When supported, the protected guest is destroyed immediately using the
new UVC, leaving only the memory to be cleaned up asynchronously.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Link: https://lore.kernel.org/r/20221111170632.77622-6-imbrenda@linux.ibm.com
Message-Id: <20221111170632.77622-6-imbrenda@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>

1 files changed, 53 insertions, 8 deletions

diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 5f958fcf6283..e032ebbf51b9 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -203,6 +203,9 @@ static int kvm_s390_pv_dispose_one_leftover(struct kvm *kvm,
 {
 	int cc;
 
+	/* It used the destroy-fast UVC, nothing left to do here */
+	if (!leftover->handle)
+		goto done_fast;
 	cc = uv_cmd_nodata(leftover->handle, UVC_CMD_DESTROY_SEC_CONF, rc, rrc);
 	KVM_UV_EVENT(kvm, 3, "PROTVIRT DESTROY LEFTOVER VM: rc %x rrc %x", *rc, *rrc);
 	WARN_ONCE(cc, "protvirt destroy leftover vm failed rc %x rrc %x", *rc, *rrc);
@@ -217,6 +220,7 @@ static int kvm_s390_pv_dispose_one_leftover(struct kvm *kvm,
 	free_pages(leftover->stor_base, get_order(uv_info.guest_base_stor_len));
 	free_pages(leftover->old_gmap_table, CRST_ALLOC_ORDER);
 	vfree(leftover->stor_var);
+done_fast:
 	atomic_dec(&kvm->mm->context.protected_count);
 	return 0;
 }
@@ -250,6 +254,36 @@ static void kvm_s390_destroy_lower_2g(struct kvm *kvm)
 	srcu_read_unlock(&kvm->srcu, srcu_idx);
 }
 
+static int kvm_s390_pv_deinit_vm_fast(struct kvm *kvm, u16 *rc, u16 *rrc)
+{
+	struct uv_cb_destroy_fast uvcb = {
+		.header.cmd = UVC_CMD_DESTROY_SEC_CONF_FAST,
+		.header.len = sizeof(uvcb),
+		.handle = kvm_s390_pv_get_handle(kvm),
+	};
+	int cc;
+
+	cc = uv_call_sched(0, (u64)&uvcb);
+	if (rc)
+		*rc = uvcb.header.rc;
+	if (rrc)
+		*rrc = uvcb.header.rrc;
+	WRITE_ONCE(kvm->arch.gmap->guest_handle, 0);
+	KVM_UV_EVENT(kvm, 3, "PROTVIRT DESTROY VM FAST: rc %x rrc %x",
+		     uvcb.header.rc, uvcb.header.rrc);
+	WARN_ONCE(cc, "protvirt destroy vm fast failed handle %llx rc %x rrc %x",
+		  kvm_s390_pv_get_handle(kvm), uvcb.header.rc, uvcb.header.rrc);
+	/* Inteded memory leak on "impossible" error */
+	if (!cc)
+		kvm_s390_pv_dealloc_vm(kvm);
+	return cc ? -EIO : 0;
+}
+
+static inline bool is_destroy_fast_available(void)
+{
+	return test_bit_inv(BIT_UVC_CMD_DESTROY_SEC_CONF_FAST, uv_info.inst_calls_list);
+}
+
 /**
  * kvm_s390_pv_set_aside - Set aside a protected VM for later teardown.
  * @kvm: the VM
@@ -271,6 +305,7 @@ static void kvm_s390_destroy_lower_2g(struct kvm *kvm)
 int kvm_s390_pv_set_aside(struct kvm *kvm, u16 *rc, u16 *rrc)
 {
 	struct pv_vm_to_be_destroyed *priv;
+	int res = 0;
 
 	lockdep_assert_held(&kvm->lock);
 	/*
@@ -283,14 +318,21 @@ int kvm_s390_pv_set_aside(struct kvm *kvm, u16 *rc, u16 *rrc)
 	if (!priv)
 		return -ENOMEM;
 
-	priv->stor_var = kvm->arch.pv.stor_var;
-	priv->stor_base = kvm->arch.pv.stor_base;
-	priv->handle = kvm_s390_pv_get_handle(kvm);
-	priv->old_gmap_table = (unsigned long)kvm->arch.gmap->table;
-	WRITE_ONCE(kvm->arch.gmap->guest_handle, 0);
-	if (s390_replace_asce(kvm->arch.gmap)) {
+	if (is_destroy_fast_available()) {
+		res = kvm_s390_pv_deinit_vm_fast(kvm, rc, rrc);
+	} else {
+		priv->stor_var = kvm->arch.pv.stor_var;
+		priv->stor_base = kvm->arch.pv.stor_base;
+		priv->handle = kvm_s390_pv_get_handle(kvm);
+		priv->old_gmap_table = (unsigned long)kvm->arch.gmap->table;
+		WRITE_ONCE(kvm->arch.gmap->guest_handle, 0);
+		if (s390_replace_asce(kvm->arch.gmap))
+			res = -ENOMEM;
+	}
+
+	if (res) {
 		kfree(priv);
-		return -ENOMEM;
+		return res;
 	}
 
 	kvm_s390_destroy_lower_2g(kvm);
@@ -471,6 +513,7 @@ static void kvm_s390_pv_mmu_notifier_release(struct mmu_notifier *subscription,
 {
 	struct kvm *kvm = container_of(subscription, struct kvm, arch.pv.mmu_notifier);
 	u16 dummy;
+	int r;
 
 	/*
 	 * No locking is needed since this is the last thread of the last user of this
@@ -479,7 +522,9 @@ static void kvm_s390_pv_mmu_notifier_release(struct mmu_notifier *subscription,
 	 * unregistered. This means that if this notifier runs, then the
 	 * struct kvm is still valid.
 	 */
-	kvm_s390_cpus_from_pv(kvm, &dummy, &dummy);
+	r = kvm_s390_cpus_from_pv(kvm, &dummy, &dummy);
+	if (!r && is_destroy_fast_available() && kvm_s390_pv_get_handle(kvm))
+		kvm_s390_pv_deinit_vm_fast(kvm, &dummy, &dummy);
 }
 
 static const struct mmu_notifier_ops kvm_s390_pv_mmu_notifier_ops = {