[PATCH v9 18/18] KVM: s390: pv: support for Destroy fast UVC

Claudio Imbrenda
2022-03-30T12:37:30Z

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>
---
arch/s390/include/asm/uv.h | 10 +++++++
arch/s390/kvm/pv.c | 57 ++++++++++++++++++++++++++++++++------
2 files changed, 58 insertions(+), 9 deletions(-)

diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index 6b2b33f19abe..b48334565415 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
@@ -76,6 +77,7 @@ 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,
};

enum uv_feat_ind {
@@ -210,6 +212,14 @@ 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 5111f1fc64ab..4ecc5658fa9a 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -187,6 +187,9 @@ static int kvm_s390_pv_cleanup_deferred(struct kvm *kvm, struct deferred_priv *d
u16 rc, rrc;
int cc;

+ /* It used the destroy-fast UVC, nothing left to do here */
+ if (!deferred->handle)
+ return 0;
cc = uv_cmd_nodata(deferred->handle, UVC_CMD_DESTROY_SEC_CONF, &rc, &rrc);
KVM_UV_EVENT(kvm, 3, "PROTVIRT DESTROY VM: rc %x rrc %x", rc, rrc);
WARN_ONCE(cc, "protvirt destroy vm failed rc %x rrc %x", rc, rrc);
@@ -291,6 +294,32 @@ static void kvm_s390_clear_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.
@@ -312,6 +341,7 @@ static void kvm_s390_clear_2g(struct kvm *kvm)
int kvm_s390_pv_deinit_vm_async_prepare(struct kvm *kvm, u16 *rc, u16 *rrc)
{
struct deferred_priv *priv;
+ int res;

/*
* If an asynchronous deinitialization is already pending, refuse.
@@ -323,14 +353,20 @@ 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_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_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_clear_2g(kvm);
@@ -393,6 +429,7 @@ 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
@@ -401,7 +438,9 @@ 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)
+ kvm_s390_pv_deinit_vm_fast(kvm, &dummy, &dummy);
}

static const struct mmu_notifier_ops kvm_s390_pv_mmu_notifier_ops = {
--
2.34.1