diff options
Diffstat (limited to 'arch/s390/kvm/pv.c')
| -rw-r--r-- | arch/s390/kvm/pv.c | 295 |
1 files changed, 285 insertions, 10 deletions
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c index 48c4f57d5d76..5f958fcf6283 100644 --- a/arch/s390/kvm/pv.c +++ b/arch/s390/kvm/pv.c @@ -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; @@ -161,23 +184,150 @@ out_err: return -ENOMEM; } -/* this should not fail, but if it does, we must not free the donated memory */ -int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc) +/** + * 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(kvm_s390_pv_get_handle(kvm), - UVC_CMD_DESTROY_SEC_CONF, rc, rrc); - WRITE_ONCE(kvm->arch.gmap->guest_handle, 0); + 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; /* - * if the mm still has a mapping, make all its pages accessible - * before destroying the guest + * 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. */ - if (mmget_not_zero(kvm->mm)) { - s390_uv_destroy_range(kvm->mm, 0, TASK_SIZE); - mmput(kvm->mm); + 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; + + 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 (!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) { |