4 files changed, 100 insertions, 1 deletions

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index bb4bf5ffb104..4bf79dbc3eeb 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -66,6 +66,11 @@ static int sev_flush_asids(void)
 	return ret;
 }
 
+static inline bool is_mirroring_enc_context(struct kvm *kvm)
+{
+	return !!to_kvm_svm(kvm)->sev_info.enc_context_owner;
+}
+
 /* Must be called with the sev_bitmap_lock held */
 static bool __sev_recycle_asids(int min_asid, int max_asid)
 {
@@ -1122,6 +1127,12 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 
 	mutex_lock(&kvm->lock);
 
+	/* enc_context_owner handles all memory enc operations */
+	if (is_mirroring_enc_context(kvm)) {
+		r = -EINVAL;
+		goto out;
+	}
+
 	switch (sev_cmd.id) {
 	case KVM_SEV_ES_INIT:
 		if (!sev_es) {
@@ -1185,6 +1196,10 @@ int svm_register_enc_region(struct kvm *kvm,
 	if (!sev_guest(kvm))
 		return -ENOTTY;
 
+	/* If kvm is mirroring encryption context it isn't responsible for it */
+	if (is_mirroring_enc_context(kvm))
+		return -EINVAL;
+
 	if (range->addr > ULONG_MAX || range->size > ULONG_MAX)
 		return -EINVAL;
 
@@ -1251,6 +1266,10 @@ int svm_unregister_enc_region(struct kvm *kvm,
 	struct enc_region *region;
 	int ret;
 
+	/* If kvm is mirroring encryption context it isn't responsible for it */
+	if (is_mirroring_enc_context(kvm))
+		return -EINVAL;
+
 	mutex_lock(&kvm->lock);
 
 	if (!sev_guest(kvm)) {
@@ -1281,6 +1300,71 @@ failed:
 	return ret;
 }
 
+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 *mirror_sev;
+	unsigned int asid;
+	int ret;
+
+	source_kvm_file = fget(source_fd);
+	if (!file_is_kvm(source_kvm_file)) {
+		ret = -EBADF;
+		goto e_source_put;
+	}
+
+	source_kvm = source_kvm_file->private_data;
+	mutex_lock(&source_kvm->lock);
+
+	if (!sev_guest(source_kvm)) {
+		ret = -EINVAL;
+		goto e_source_unlock;
+	}
+
+	/* Mirrors of mirrors should work, but let's not get silly */
+	if (is_mirroring_enc_context(source_kvm) || source_kvm == kvm) {
+		ret = -EINVAL;
+		goto e_source_unlock;
+	}
+
+	asid = to_kvm_svm(source_kvm)->sev_info.asid;
+
+	/*
+	 * The mirror kvm holds an enc_context_owner ref so its asid can't
+	 * disappear until we're done with it
+	 */
+	kvm_get_kvm(source_kvm);
+
+	fput(source_kvm_file);
+	mutex_unlock(&source_kvm->lock);
+	mutex_lock(&kvm->lock);
+
+	if (sev_guest(kvm)) {
+		ret = -EINVAL;
+		goto e_mirror_unlock;
+	}
+
+	/* 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->asid = asid;
+	mirror_sev->active = true;
+
+	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:
+	fput(source_kvm_file);
+	return ret;
+}
+
 void sev_vm_destroy(struct kvm *kvm)
 {
 	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
@@ -1290,6 +1374,12 @@ void sev_vm_destroy(struct kvm *kvm)
 	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);
+		return;
+	}
+
 	mutex_lock(&kvm->lock);
 
 	/*
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 86e42d42637e..cd8c333ed2dc 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4589,6 +4589,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 	.mem_enc_reg_region = svm_register_enc_region,
 	.mem_enc_unreg_region = svm_unregister_enc_region,
 
+	.vm_copy_enc_context_from = svm_vm_copy_asid_from,
+
 	.can_emulate_instruction = svm_can_emulate_instruction,
 
 	.apic_init_signal_blocked = svm_apic_init_signal_blocked,
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 7deb7a057004..454da1c1d9b7 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -68,6 +68,7 @@ struct kvm_sev_info {
 	unsigned long pages_locked; /* Number of pages locked */
 	struct list_head regions_list;  /* List of registered regions */
 	u64 ap_jump_table;	/* SEV-ES AP Jump Table address */
+	struct kvm *enc_context_owner; /* Owner of copied encryption context */
 };
 
 struct kvm_svm {
@@ -580,6 +581,7 @@ int svm_register_enc_region(struct kvm *kvm,
 			    struct kvm_enc_region *range);
 int svm_unregister_enc_region(struct kvm *kvm,
 			      struct kvm_enc_region *range);
+int svm_vm_copy_asid_from(struct kvm *kvm, unsigned int source_fd);
 void pre_sev_run(struct vcpu_svm *svm, int cpu);
 void __init sev_hardware_setup(void);
 void sev_hardware_teardown(void);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d4cdab15238b..a5eeca55810f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3808,6 +3808,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 #ifdef CONFIG_X86_SGX_KVM
 	case KVM_CAP_SGX_ATTRIBUTE:
 #endif
+	case KVM_CAP_VM_COPY_ENC_CONTEXT_FROM:
 		r = 1;
 		break;
 	case KVM_CAP_SET_GUEST_DEBUG2:
@@ -4714,7 +4715,6 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
 			kvm_update_pv_runtime(vcpu);
 
 		return 0;
-
 	default:
 		return -EINVAL;
 	}
@@ -5413,6 +5413,11 @@ split_irqchip_unlock:
 		break;
 	}
 #endif
+	case KVM_CAP_VM_COPY_ENC_CONTEXT_FROM:
+		r = -EINVAL;
+		if (kvm_x86_ops.vm_copy_enc_context_from)
+			r = kvm_x86_ops.vm_copy_enc_context_from(kvm, cap->args[0]);
+		return r;
 	default:
 		r = -EINVAL;
 		break;