1 files changed, 86 insertions, 75 deletions

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 21ac0a5de4e0..59727a966f90 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1543,28 +1543,50 @@ static bool is_cmd_allowed_from_mirror(u32 cmd_id)
 	return false;
 }
 
-static int sev_lock_for_migration(struct kvm *kvm)
+static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)
 {
-	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+	struct kvm_sev_info *dst_sev = &to_kvm_svm(dst_kvm)->sev_info;
+	struct kvm_sev_info *src_sev = &to_kvm_svm(src_kvm)->sev_info;
+	int r = -EBUSY;
+
+	if (dst_kvm == src_kvm)
+		return -EINVAL;
 
 	/*
-	 * Bail if this VM is already involved in a migration to avoid deadlock
-	 * between two VMs trying to migrate to/from each other.
+	 * Bail if these VMs are already involved in a migration to avoid
+	 * deadlock between two VMs trying to migrate to/from each other.
 	 */
-	if (atomic_cmpxchg_acquire(&sev->migration_in_progress, 0, 1))
+	if (atomic_cmpxchg_acquire(&dst_sev->migration_in_progress, 0, 1))
 		return -EBUSY;
 
-	mutex_lock(&kvm->lock);
+	if (atomic_cmpxchg_acquire(&src_sev->migration_in_progress, 0, 1))
+		goto release_dst;
 
+	r = -EINTR;
+	if (mutex_lock_killable(&dst_kvm->lock))
+		goto release_src;
+	if (mutex_lock_killable(&src_kvm->lock))
+		goto unlock_dst;
 	return 0;
+
+unlock_dst:
+	mutex_unlock(&dst_kvm->lock);
+release_src:
+	atomic_set_release(&src_sev->migration_in_progress, 0);
+release_dst:
+	atomic_set_release(&dst_sev->migration_in_progress, 0);
+	return r;
 }
 
-static void sev_unlock_after_migration(struct kvm *kvm)
+static void sev_unlock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)
 {
-	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+	struct kvm_sev_info *dst_sev = &to_kvm_svm(dst_kvm)->sev_info;
+	struct kvm_sev_info *src_sev = &to_kvm_svm(src_kvm)->sev_info;
 
-	mutex_unlock(&kvm->lock);
-	atomic_set_release(&sev->migration_in_progress, 0);
+	mutex_unlock(&dst_kvm->lock);
+	mutex_unlock(&src_kvm->lock);
+	atomic_set_release(&dst_sev->migration_in_progress, 0);
+	atomic_set_release(&src_sev->migration_in_progress, 0);
 }
 
 
@@ -1607,14 +1629,15 @@ static void sev_migrate_from(struct kvm_sev_info *dst,
 	dst->asid = src->asid;
 	dst->handle = src->handle;
 	dst->pages_locked = src->pages_locked;
+	dst->enc_context_owner = src->enc_context_owner;
 
 	src->asid = 0;
 	src->active = false;
 	src->handle = 0;
 	src->pages_locked = 0;
+	src->enc_context_owner = NULL;
 
-	INIT_LIST_HEAD(&dst->regions_list);
-	list_replace_init(&src->regions_list, &dst->regions_list);
+	list_cut_before(&dst->regions_list, &src->regions_list, &src->regions_list);
 }
 
 static int sev_es_migrate_from(struct kvm *dst, struct kvm *src)
@@ -1666,15 +1689,6 @@ int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
 	bool charged = false;
 	int ret;
 
-	ret = sev_lock_for_migration(kvm);
-	if (ret)
-		return ret;
-
-	if (sev_guest(kvm)) {
-		ret = -EINVAL;
-		goto out_unlock;
-	}
-
 	source_kvm_file = fget(source_fd);
 	if (!file_is_kvm(source_kvm_file)) {
 		ret = -EBADF;
@@ -1682,16 +1696,26 @@ int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
 	}
 
 	source_kvm = source_kvm_file->private_data;
-	ret = sev_lock_for_migration(source_kvm);
+	ret = sev_lock_two_vms(kvm, source_kvm);
 	if (ret)
 		goto out_fput;
 
-	if (!sev_guest(source_kvm)) {
+	if (sev_guest(kvm) || !sev_guest(source_kvm)) {
 		ret = -EINVAL;
-		goto out_source;
+		goto out_unlock;
 	}
 
 	src_sev = &to_kvm_svm(source_kvm)->sev_info;
+
+	/*
+	 * VMs mirroring src's encryption context rely on it to keep the
+	 * ASID allocated, but below we are clearing src_sev->asid.
+	 */
+	if (src_sev->num_mirrored_vms) {
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+
 	dst_sev->misc_cg = get_current_misc_cg();
 	cg_cleanup_sev = dst_sev;
 	if (dst_sev->misc_cg != src_sev->misc_cg) {
@@ -1728,13 +1752,11 @@ out_dst_cgroup:
 		sev_misc_cg_uncharge(cg_cleanup_sev);
 	put_misc_cg(cg_cleanup_sev->misc_cg);
 	cg_cleanup_sev->misc_cg = NULL;
-out_source:
-	sev_unlock_after_migration(source_kvm);
+out_unlock:
+	sev_unlock_two_vms(kvm, source_kvm);
 out_fput:
 	if (source_kvm_file)
 		fput(source_kvm_file);
-out_unlock:
-	sev_unlock_after_migration(kvm);
 	return ret;
 }
 
@@ -1953,76 +1975,60 @@ int svm_vm_copy_asid_from(struct kvm *kvm, unsigned int source_fd)
 {
 	struct file *source_kvm_file;
 	struct kvm *source_kvm;
-	struct kvm_sev_info source_sev, *mirror_sev;
+	struct kvm_sev_info *source_sev, *mirror_sev;
 	int ret;
 
 	source_kvm_file = fget(source_fd);
 	if (!file_is_kvm(source_kvm_file)) {
 		ret = -EBADF;
-		goto e_source_put;
+		goto e_source_fput;
 	}
 
 	source_kvm = source_kvm_file->private_data;
-	mutex_lock(&source_kvm->lock);
-
-	if (!sev_guest(source_kvm)) {
-		ret = -EINVAL;
-		goto e_source_unlock;
-	}
+	ret = sev_lock_two_vms(kvm, source_kvm);
+	if (ret)
+		goto e_source_fput;
 
-	/* Mirrors of mirrors should work, but let's not get silly */
-	if (is_mirroring_enc_context(source_kvm) || source_kvm == kvm) {
+	/*
+	 * Mirrors of mirrors should work, but let's not get silly.  Also
+	 * disallow out-of-band SEV/SEV-ES init if the target is already an
+	 * SEV guest, or if vCPUs have been created.  KVM relies on vCPUs being
+	 * created after SEV/SEV-ES initialization, e.g. to init intercepts.
+	 */
+	if (sev_guest(kvm) || !sev_guest(source_kvm) ||
+	    is_mirroring_enc_context(source_kvm) || kvm->created_vcpus) {
 		ret = -EINVAL;
-		goto e_source_unlock;
+		goto e_unlock;
 	}
 
-	memcpy(&source_sev, &to_kvm_svm(source_kvm)->sev_info,
-	       sizeof(source_sev));
-
 	/*
 	 * The mirror kvm holds an enc_context_owner ref so its asid can't
 	 * disappear until we're done with it
 	 */
+	source_sev = &to_kvm_svm(source_kvm)->sev_info;
 	kvm_get_kvm(source_kvm);
-
-	fput(source_kvm_file);
-	mutex_unlock(&source_kvm->lock);
-	mutex_lock(&kvm->lock);
-
-	/*
-	 * Disallow out-of-band SEV/SEV-ES init if the target is already an
-	 * SEV guest, or if vCPUs have been created.  KVM relies on vCPUs being
-	 * created after SEV/SEV-ES initialization, e.g. to init intercepts.
-	 */
-	if (sev_guest(kvm) || kvm->created_vcpus) {
-		ret = -EINVAL;
-		goto e_mirror_unlock;
-	}
+	source_sev->num_mirrored_vms++;
 
 	/* Set enc_context_owner and copy its encryption context over */
 	mirror_sev = &to_kvm_svm(kvm)->sev_info;
 	mirror_sev->enc_context_owner = source_kvm;
 	mirror_sev->active = true;
-	mirror_sev->asid = source_sev.asid;
-	mirror_sev->fd = source_sev.fd;
-	mirror_sev->es_active = source_sev.es_active;
-	mirror_sev->handle = source_sev.handle;
+	mirror_sev->asid = source_sev->asid;
+	mirror_sev->fd = source_sev->fd;
+	mirror_sev->es_active = source_sev->es_active;
+	mirror_sev->handle = source_sev->handle;
+	INIT_LIST_HEAD(&mirror_sev->regions_list);
+	ret = 0;
+
 	/*
 	 * Do not copy ap_jump_table. Since the mirror does not share the same
 	 * KVM contexts as the original, and they may have different
 	 * memory-views.
 	 */
 
-	mutex_unlock(&kvm->lock);
-	return 0;
-
-e_mirror_unlock:
-	mutex_unlock(&kvm->lock);
-	kvm_put_kvm(source_kvm);
-	return ret;
-e_source_unlock:
-	mutex_unlock(&source_kvm->lock);
-e_source_put:
+e_unlock:
+	sev_unlock_two_vms(kvm, source_kvm);
+e_source_fput:
 	if (source_kvm_file)
 		fput(source_kvm_file);
 	return ret;
@@ -2034,17 +2040,24 @@ void sev_vm_destroy(struct kvm *kvm)
 	struct list_head *head = &sev->regions_list;
 	struct list_head *pos, *q;
 
+	WARN_ON(sev->num_mirrored_vms);
+
 	if (!sev_guest(kvm))
 		return;
 
 	/* If this is a mirror_kvm release the enc_context_owner and skip sev cleanup */
 	if (is_mirroring_enc_context(kvm)) {
-		kvm_put_kvm(sev->enc_context_owner);
+		struct kvm *owner_kvm = sev->enc_context_owner;
+		struct kvm_sev_info *owner_sev = &to_kvm_svm(owner_kvm)->sev_info;
+
+		mutex_lock(&owner_kvm->lock);
+		if (!WARN_ON(!owner_sev->num_mirrored_vms))
+			owner_sev->num_mirrored_vms--;
+		mutex_unlock(&owner_kvm->lock);
+		kvm_put_kvm(owner_kvm);
 		return;
 	}
 
-	mutex_lock(&kvm->lock);
-
 	/*
 	 * Ensure that all guest tagged cache entries are flushed before
 	 * releasing the pages back to the system for use. CLFLUSH will
@@ -2064,8 +2077,6 @@ void sev_vm_destroy(struct kvm *kvm)
 		}
 	}
 
-	mutex_unlock(&kvm->lock);
-
 	sev_unbind_asid(kvm, sev->handle);
 	sev_asid_free(sev);
 }