@@ -942,6 +942,8 @@ struct kvm_s390_pv {
unsigned long stor_base;
void *stor_var;
bool dumping;
+ void *set_aside;
+ struct list_head need_cleanup;
struct mmu_notifier mmu_notifier;
};
@@ -209,6 +209,8 @@ unsigned int diag9c_forwarding_hz;
module_param(diag9c_forwarding_hz, uint, 0644);
MODULE_PARM_DESC(diag9c_forwarding_hz, "Maximum diag9c forwarding per second, 0 to turn off");
+static int async_destroy;
+
/*
* For now we handle at most 16 double words as this is what the s390 base
* kernel handles and stores in the prefix page. If we ever need to go beyond
@@ -2504,9 +2506,13 @@ static int kvm_s390_pv_dmp(struct kvm *kvm, struct kvm_pv_cmd *cmd,
static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
{
+ const bool need_lock = (cmd->cmd != KVM_PV_ASYNC_CLEANUP_PERFORM);
+ void __user *argp = (void __user *)cmd->data;
int r = 0;
u16 dummy;
- void __user *argp = (void __user *)cmd->data;
+
+ if (need_lock)
+ mutex_lock(&kvm->lock);
switch (cmd->cmd) {
case KVM_PV_ENABLE: {
@@ -2540,6 +2546,31 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
set_bit(IRQ_PEND_EXT_SERVICE, &kvm->arch.float_int.masked_irqs);
break;
}
+ case KVM_PV_ASYNC_CLEANUP_PREPARE:
+ r = -EINVAL;
+ if (!kvm_s390_pv_is_protected(kvm) || !async_destroy)
+ break;
+
+ r = kvm_s390_cpus_from_pv(kvm, &cmd->rc, &cmd->rrc);
+ /*
+ * If a CPU could not be destroyed, destroy VM will also fail.
+ * There is no point in trying to destroy it. Instead return
+ * the rc and rrc from the first CPU that failed destroying.
+ */
+ if (r)
+ break;
+ r = kvm_s390_pv_set_aside(kvm, &cmd->rc, &cmd->rrc);
+
+ /* no need to block service interrupts any more */
+ clear_bit(IRQ_PEND_EXT_SERVICE, &kvm->arch.float_int.masked_irqs);
+ break;
+ case KVM_PV_ASYNC_CLEANUP_PERFORM:
+ r = -EINVAL;
+ if (!async_destroy)
+ break;
+ /* kvm->lock must not be held; this is asserted inside the function. */
+ r = kvm_s390_pv_deinit_aside_vm(kvm, &cmd->rc, &cmd->rrc);
+ break;
case KVM_PV_DISABLE: {
r = -EINVAL;
if (!kvm_s390_pv_is_protected(kvm))
@@ -2553,7 +2584,7 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
*/
if (r)
break;
- r = kvm_s390_pv_deinit_vm(kvm, &cmd->rc, &cmd->rrc);
+ r = kvm_s390_pv_deinit_cleanup_all(kvm, &cmd->rc, &cmd->rrc);
/* no need to block service interrupts any more */
clear_bit(IRQ_PEND_EXT_SERVICE, &kvm->arch.float_int.masked_irqs);
@@ -2703,6 +2734,9 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
default:
r = -ENOTTY;
}
+ if (need_lock)
+ mutex_unlock(&kvm->lock);
+
return r;
}
@@ -2907,9 +2941,8 @@ long kvm_arch_vm_ioctl(struct file *filp,
r = -EINVAL;
break;
}
- mutex_lock(&kvm->lock);
+ /* must be called without kvm->lock */
r = kvm_s390_handle_pv(kvm, &args);
- mutex_unlock(&kvm->lock);
if (copy_to_user(argp, &args, sizeof(args))) {
r = -EFAULT;
break;
@@ -3228,6 +3261,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
kvm_s390_vsie_init(kvm);
if (use_gisa)
kvm_s390_gisa_init(kvm);
+ INIT_LIST_HEAD(&kvm->arch.pv.need_cleanup);
+ kvm->arch.pv.set_aside = NULL;
KVM_EVENT(3, "vm 0x%pK created by pid %u", kvm, current->pid);
return 0;
@@ -3272,11 +3307,9 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
/*
* We are already at the end of life and kvm->lock is not taken.
* This is ok as the file descriptor is closed by now and nobody
- * can mess with the pv state. To avoid lockdep_assert_held from
- * complaining we do not use kvm_s390_pv_is_protected.
+ * can mess with the pv state.
*/
- if (kvm_s390_pv_get_handle(kvm))
- kvm_s390_pv_deinit_vm(kvm, &rc, &rrc);
+ kvm_s390_pv_deinit_cleanup_all(kvm, &rc, &rrc);
/*
* Remove the mmu notifier only when the whole KVM VM is torn down,
* and only if one was registered to begin with. If the VM is
@@ -244,6 +244,9 @@ static inline u32 kvm_s390_get_gisa_desc(struct kvm *kvm)
/* implemented in pv.c */
int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc);
int kvm_s390_pv_create_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc);
+int kvm_s390_pv_set_aside(struct kvm *kvm, u16 *rc, u16 *rrc);
+int kvm_s390_pv_deinit_aside_vm(struct kvm *kvm, u16 *rc, u16 *rrc);
+int kvm_s390_pv_deinit_cleanup_all(struct kvm *kvm, u16 *rc, u16 *rrc);
int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc);
int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc);
int kvm_s390_pv_set_sec_parms(struct kvm *kvm, void *hdr, u64 length, u16 *rc,
@@ -18,6 +18,29 @@
#include <linux/mmu_notifier.h>
#include "kvm-s390.h"
+/**
+ * struct pv_vm_to_be_destroyed - Represents a protected VM that needs to
+ * be destroyed
+ *
+ * @list: list head for the list of leftover VMs
+ * @old_gmap_table: the gmap table of the leftover protected VM
+ * @handle: the handle of the leftover protected VM
+ * @stor_var: pointer to the variable storage of the leftover protected VM
+ * @stor_base: address of the base storage of the leftover protected VM
+ *
+ * Represents a protected VM that is still registered with the Ultravisor,
+ * but which does not correspond any longer to an active KVM VM. It should
+ * be destroyed at some point later, either asynchronously or when the
+ * process terminates.
+ */
+struct pv_vm_to_be_destroyed {
+ struct list_head list;
+ unsigned long old_gmap_table;
+ u64 handle;
+ void *stor_var;
+ unsigned long stor_base;
+};
+
static void kvm_s390_clear_pv_state(struct kvm *kvm)
{
kvm->arch.pv.handle = 0;
@@ -161,7 +184,143 @@ static int kvm_s390_pv_alloc_vm(struct kvm *kvm)
return -ENOMEM;
}
-/* this should not fail, but if it does, we must not free the donated memory */
+/**
+ * kvm_s390_pv_dispose_one_leftover - Clean up one leftover protected VM.
+ * @kvm: the KVM that was associated with this leftover protected VM
+ * @leftover: details about the leftover protected VM that needs a clean up
+ * @rc: the RC code of the Destroy Secure Configuration UVC
+ * @rrc: the RRC code of the Destroy Secure Configuration UVC
+ *
+ * Destroy one leftover protected VM.
+ * On success, kvm->mm->context.protected_count will be decremented atomically
+ * and all other resources used by the VM will be freed.
+ *
+ * Return: 0 in case of success, otherwise 1
+ */
+static int kvm_s390_pv_dispose_one_leftover(struct kvm *kvm,
+ struct pv_vm_to_be_destroyed *leftover,
+ u16 *rc, u16 *rrc)
+{
+ int cc;
+
+ 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);
+ if (cc)
+ return cc;
+ /*
+ * Intentionally leak unusable memory. If the UVC fails, the memory
+ * used for the VM and its metadata is permanently unusable.
+ * This can only happen in case of a serious KVM or hardware bug; it
+ * is not expected to happen in normal operation.
+ */
+ 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);
+ atomic_dec(&kvm->mm->context.protected_count);
+ return 0;
+}
+
+/**
+ * kvm_s390_destroy_lower_2g - Destroy the first 2GB of protected guest memory.
+ * @kvm: the VM whose memory is to be cleared.
+ *
+ * Destroy the first 2GB of guest memory, to avoid prefix issues after reboot.
+ * The CPUs of the protected VM need to be destroyed beforehand.
+ */
+static void kvm_s390_destroy_lower_2g(struct kvm *kvm)
+{
+ const unsigned long pages_2g = SZ_2G / PAGE_SIZE;
+ struct kvm_memory_slot *slot;
+ unsigned long len;
+ int srcu_idx;
+
+ srcu_idx = srcu_read_lock(&kvm->srcu);
+
+ /* Take the memslot containing guest absolute address 0 */
+ slot = gfn_to_memslot(kvm, 0);
+ /* Clear all slots or parts thereof that are below 2GB */
+ while (slot && slot->base_gfn < pages_2g) {
+ len = min_t(u64, slot->npages, pages_2g - slot->base_gfn) * PAGE_SIZE;
+ s390_uv_destroy_range(kvm->mm, slot->userspace_addr, slot->userspace_addr + len);
+ /* Take the next memslot */
+ slot = gfn_to_memslot(kvm, slot->base_gfn + slot->npages);
+ }
+
+ srcu_read_unlock(&kvm->srcu, srcu_idx);
+}
+
+/**
+ * kvm_s390_pv_set_aside - Set aside a protected VM for later teardown.
+ * @kvm: the VM
+ * @rc: return value for the RC field of the UVCB
+ * @rrc: return value for the RRC field of the UVCB
+ *
+ * Set aside the protected VM for a subsequent teardown. The VM will be able
+ * to continue immediately as a non-secure VM, and the information needed to
+ * properly tear down the protected VM is set aside. If another protected VM
+ * was already set aside without starting its teardown, this function will
+ * fail.
+ * The CPUs of the protected VM need to be destroyed beforehand.
+ *
+ * Context: kvm->lock needs to be held
+ *
+ * Return: 0 in case of success, -EINVAL if another protected VM was already set
+ * aside, -ENOMEM if the system ran out of memory.
+ */
+int kvm_s390_pv_set_aside(struct kvm *kvm, u16 *rc, u16 *rrc)
+{
+ struct pv_vm_to_be_destroyed *priv;
+
+ lockdep_assert_held(&kvm->lock);
+ /*
+ * If another protected VM was already prepared for teardown, refuse.
+ * A normal deinitialization has to be performed instead.
+ */
+ if (kvm->arch.pv.set_aside)
+ return -EINVAL;
+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ 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;
+ }
+
+ kvm_s390_destroy_lower_2g(kvm);
+ kvm_s390_clear_pv_state(kvm);
+ kvm->arch.pv.set_aside = priv;
+
+ *rc = UVC_RC_EXECUTED;
+ *rrc = 42;
+ return 0;
+}
+
+/**
+ * kvm_s390_pv_deinit_vm - Deinitialize the current protected VM
+ * @kvm: the KVM whose protected VM needs to be deinitialized
+ * @rc: the RC code of the UVC
+ * @rrc: the RRC code of the UVC
+ *
+ * Deinitialize the current protected VM. This function will destroy and
+ * cleanup the current protected VM, but it will not cleanup the guest
+ * memory. This function should only be called when the protected VM has
+ * just been created and therefore does not have any guest memory, or when
+ * the caller cleans up the guest memory separately.
+ *
+ * This function should not fail, but if it does, the donated memory must
+ * not be freed.
+ *
+ * Context: kvm->lock needs to be held
+ *
+ * Return: 0 in case of success, otherwise -EIO
+ */
int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
{
int cc;
@@ -169,15 +328,6 @@ int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
cc = uv_cmd_nodata(kvm_s390_pv_get_handle(kvm),
UVC_CMD_DESTROY_SEC_CONF, rc, rrc);
WRITE_ONCE(kvm->arch.gmap->guest_handle, 0);
- /*
- * if the mm still has a mapping, make all its pages accessible
- * before destroying the guest
- */
- if (mmget_not_zero(kvm->mm)) {
- s390_uv_destroy_range(kvm->mm, 0, TASK_SIZE);
- mmput(kvm->mm);
- }
-
if (!cc) {
atomic_dec(&kvm->mm->context.protected_count);
kvm_s390_pv_dealloc_vm(kvm);
@@ -191,6 +341,131 @@ int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
return cc ? -EIO : 0;
}
+/**
+ * kvm_s390_pv_deinit_cleanup_all - Clean up all protected VMs associated
+ * with a specific KVM.
+ * @kvm: the KVM to be cleaned up
+ * @rc: the RC code of the first failing UVC
+ * @rrc: the RRC code of the first failing UVC
+ *
+ * This function will clean up all protected VMs associated with a KVM.
+ * This includes the active one, the one prepared for deinitialization with
+ * kvm_s390_pv_set_aside, and any still pending in the need_cleanup list.
+ *
+ * Context: kvm->lock needs to be held unless being called from
+ * kvm_arch_destroy_vm.
+ *
+ * Return: 0 if all VMs are successfully cleaned up, otherwise -EIO
+ */
+int kvm_s390_pv_deinit_cleanup_all(struct kvm *kvm, u16 *rc, u16 *rrc)
+{
+ struct pv_vm_to_be_destroyed *cur;
+ bool need_zap = false;
+ u16 _rc, _rrc;
+ int cc = 0;
+
+ /* Make sure the counter does not reach 0 before calling s390_uv_destroy_range */
+ atomic_inc(&kvm->mm->context.protected_count);
+
+ *rc = 1;
+ /* If the current VM is protected, destroy it */
+ if (kvm_s390_pv_get_handle(kvm)) {
+ cc = kvm_s390_pv_deinit_vm(kvm, rc, rrc);
+ need_zap = true;
+ }
+
+ /* If a previous protected VM was set aside, put it in the need_cleanup list */
+ if (kvm->arch.pv.set_aside) {
+ list_add(kvm->arch.pv.set_aside, &kvm->arch.pv.need_cleanup);
+ kvm->arch.pv.set_aside = NULL;
+ }
+
+ /* Cleanup all protected VMs in the need_cleanup list */
+ while (!list_empty(&kvm->arch.pv.need_cleanup)) {
+ cur = list_first_entry(&kvm->arch.pv.need_cleanup, typeof(*cur), list);
+ need_zap = true;
+ if (kvm_s390_pv_dispose_one_leftover(kvm, cur, &_rc, &_rrc)) {
+ cc = 1;
+ /*
+ * Only return the first error rc and rrc, so make
+ * sure it is not overwritten. All destroys will
+ * additionally be reported via KVM_UV_EVENT().
+ */
+ if (*rc == UVC_RC_EXECUTED) {
+ *rc = _rc;
+ *rrc = _rrc;
+ }
+ }
+ list_del(&cur->list);
+ kfree(cur);
+ }
+
+ /*
+ * If the mm still has a mapping, try to mark all its pages as
+ * accessible. The counter should not reach zero before this
+ * cleanup has been performed.
+ */
+ if (need_zap && mmget_not_zero(kvm->mm)) {
+ s390_uv_destroy_range(kvm->mm, 0, TASK_SIZE);
+ mmput(kvm->mm);
+ }
+
+ /* Now the counter can safely reach 0 */
+ atomic_dec(&kvm->mm->context.protected_count);
+ return cc ? -EIO : 0;
+}
+
+/**
+ * kvm_s390_pv_deinit_aside_vm - Teardown a previously set aside protected VM.
+ * @kvm: the VM previously associated with the protected VM
+ * @rc: return value for the RC field of the UVCB
+ * @rrc: return value for the RRC field of the UVCB
+ *
+ * Tear down the protected VM that had been previously prepared for teardown
+ * using kvm_s390_pv_set_aside_vm. Ideally this should be called by
+ * userspace asynchronously from a separate thread.
+ *
+ * Context: kvm->lock must not be held.
+ *
+ * Return: 0 in case of success, -EINVAL if no protected VM had been
+ * prepared for asynchronous teardowm, -EIO in case of other errors.
+ */
+int kvm_s390_pv_deinit_aside_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
+{
+ struct pv_vm_to_be_destroyed *p;
+ int ret = 0;
+
+ lockdep_assert_not_held(&kvm->lock);
+ mutex_lock(&kvm->lock);
+ p = kvm->arch.pv.set_aside;
+ kvm->arch.pv.set_aside = NULL;
+ mutex_unlock(&kvm->lock);
+ if (!p)
+ return -EINVAL;
+
+ /* When a fatal signal is received, stop immediately */
+ if (s390_uv_destroy_range_interruptible(kvm->mm, 0, TASK_SIZE_MAX))
+ goto done;
+ if (kvm_s390_pv_dispose_one_leftover(kvm, p, rc, rrc))
+ ret = -EIO;
+ kfree(p);
+ p = NULL;
+done:
+ /*
+ * p is not NULL if we aborted because of a fatal signal, in which
+ * case queue the leftover for later cleanup.
+ */
+ if (p) {
+ mutex_lock(&kvm->lock);
+ list_add(&p->list, &kvm->arch.pv.need_cleanup);
+ mutex_unlock(&kvm->lock);
+ /* Did not finish, but pretend things went well */
+ *rc = UVC_RC_EXECUTED;
+ *rrc = 42;
+ }
+ return ret;
+}
+
static void kvm_s390_pv_mmu_notifier_release(struct mmu_notifier *subscription,
struct mm_struct *mm)
{
@@ -1740,6 +1740,8 @@ enum pv_cmd_id {
KVM_PV_UNSHARE_ALL,
KVM_PV_INFO,
KVM_PV_DUMP,
+ KVM_PV_ASYNC_CLEANUP_PREPARE,
+ KVM_PV_ASYNC_CLEANUP_PERFORM,
};
struct kvm_pv_cmd {