[PATCH v11 19/19] KVM: s390: pv: support for Destroy fast UVC

[Claudio Imbrenda]

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@xxxxxxxxxxxxx>
---
 arch/s390/include/asm/uv.h | 10 +++++++
 arch/s390/kvm/pv.c         | 58 ++++++++++++++++++++++++++++++++------
 2 files changed, 59 insertions(+), 9 deletions(-)

diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index ba64e0be03bb..8b255d26c5a7 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -34,6 +34,7 @@
 #define UVC_CMD_INIT_UV			0x000f
 #define UVC_CMD_CREATE_SEC_CONF		0x0100
 #define UVC_CMD_DESTROY_SEC_CONF	0x0101
+#define UVC_CMD_DESTROY_SEC_CONF_FAST	0x0102
 #define UVC_CMD_CREATE_SEC_CPU		0x0120
 #define UVC_CMD_DESTROY_SEC_CPU		0x0121
 #define UVC_CMD_CONV_TO_SEC_STOR	0x0200
@@ -77,6 +78,7 @@ enum uv_cmds_inst {
 	BIT_UVC_CMD_UNSHARE_ALL = 20,
 	BIT_UVC_CMD_PIN_PAGE_SHARED = 21,
 	BIT_UVC_CMD_UNPIN_PAGE_SHARED = 22,
+	BIT_UVC_CMD_DESTROY_SEC_CONF_FAST = 23,
 	BIT_UVC_CMD_RETR_ATTEST = 28,
 };
 
@@ -213,6 +215,14 @@ struct uv_cb_nodata {
 	u64 reserved20[4];
 } __packed __aligned(8);
 
+/* Destroy Configuration Fast */
+struct uv_cb_destroy_fast {
+	struct uv_cb_header header;
+	u64 reserved08[2];
+	u64 handle;
+	u64 reserved20[5];
+} __packed __aligned(8);
+
 /* Set Shared Access */
 struct uv_cb_share {
 	struct uv_cb_header header;
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index ab06fa366e49..51c35df41a83 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -188,6 +188,9 @@ static int kvm_s390_pv_dispose_one_leftover(struct kvm *kvm, struct leftover_pv_
 {
 	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);
@@ -202,6 +205,7 @@ static int kvm_s390_pv_dispose_one_leftover(struct kvm *kvm, struct leftover_pv_
 	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;
 }
@@ -310,6 +314,32 @@ 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);
+	*rc = uvcb.header.rc;
+	*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", *rc, *rrc);
+	WARN_ONCE(cc, "protvirt destroy vm fast failed rc %x rrc %x", *rc, *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_deinit_vm_async_prepare - Prepare a protected VM for
  * asynchronous teardown.
@@ -331,6 +361,7 @@ static void kvm_s390_destroy_lower_2g(struct kvm *kvm)
 int kvm_s390_pv_deinit_vm_async_prepare(struct kvm *kvm, u16 *rc, u16 *rrc)
 {
 	struct leftover_pv_vm *priv;
+	int res;
 
 	/*
 	 * If an asynchronous deinitialization is already pending, refuse.
@@ -342,14 +373,20 @@ int kvm_s390_pv_deinit_vm_async_prepare(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)) {
-		kfree(priv);
-		return -ENOMEM;
+	if (is_destroy_fast_available()) {
+		res = kvm_s390_pv_deinit_vm_fast(kvm, rc, rrc);
+		if (res)
+			return res;
+	} 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)) {
+			kfree(priv);
+			return -ENOMEM;
+		}
 	}
 
 	kvm_s390_destroy_lower_2g(kvm);
@@ -415,6 +452,7 @@ 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
@@ -423,7 +461,9 @@ 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_deinit_vm_fast(kvm, &dummy, &dummy);
 }
 
 static const struct mmu_notifier_ops kvm_s390_pv_mmu_notifier_ops = {
-- 
2.36.1