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KVM: s390: pv: support for Destroy fast UVC
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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>
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Claudio Imbrenda authored and Janosch Frank committed Nov 23, 2022
1 parent afe20eb commit f7866f5
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Showing 2 changed files with 63 additions and 8 deletions.
10 changes: 10 additions & 0 deletions arch/s390/include/asm/uv.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -81,6 +82,7 @@ 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_DUMP_INIT = 24,
BIT_UVC_CMD_DUMP_CONFIG_STOR_STATE = 25,
BIT_UVC_CMD_DUMP_CPU = 26,
Expand Down Expand Up @@ -230,6 +232,14 @@ 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;
Expand Down
61 changes: 53 additions & 8 deletions arch/s390/kvm/pv.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand All @@ -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;
}
Expand Down Expand Up @@ -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
Expand All @@ -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);
/*
Expand All @@ -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);
Expand Down Expand Up @@ -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
Expand All @@ -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 = {
Expand Down

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