diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 3b093d6dbe22c40c441979c159c9a48d5154e86f..aeeb071c7688198cf0f5e29af3b431e8604c742b 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -6911,6 +6911,20 @@ MAP_SHARED mmap will result in an -EINVAL return.
When enabled the VMM may make use of the ``KVM_ARM_MTE_COPY_TAGS`` ioctl to
perform a bulk copy of tags to/from the guest.
+7.29 KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM
+-------------------------------------
+
+Architectures: x86 SEV enabled
+Type: vm
+Parameters: args[0] is the fd of the source vm
+Returns: 0 on success
+
+This capability enables userspace to migrate the encryption context from the VM
+indicated by the fd to the VM this is called on.
+
+This is intended to support intra-host migration of VMs between userspace VMMs,
+upgrading the VMM process without interrupting the guest.
+
8. Other capabilities.
======================
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 88fce6ab4bbd7cf8af0827c6666ef2d17c4d733d..0e9d1786c86504c68538cd23ea5b15306811816b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1476,6 +1476,7 @@ struct kvm_x86_ops {
int (*mem_enc_reg_region)(struct kvm *kvm, struct kvm_enc_region *argp);
int (*mem_enc_unreg_region)(struct kvm *kvm, struct kvm_enc_region *argp);
int (*vm_copy_enc_context_from)(struct kvm *kvm, unsigned int source_fd);
+ int (*vm_move_enc_context_from)(struct kvm *kvm, unsigned int source_fd);
int (*get_msr_feature)(struct kvm_msr_entry *entry);
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 227becd93cb6d83b95d73eb6469782501f66a4bf..8b529022f0cf00c8440dbe885ee62f359015f957 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1532,6 +1532,158 @@ static bool cmd_allowed_from_miror(u32 cmd_id)
return false;
}
+static int sev_lock_for_migration(struct kvm *kvm)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+
+ /*
+ * Bail if this VM is 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))
+ return -EBUSY;
+
+ mutex_lock(&kvm->lock);
+
+ return 0;
+}
+
+static void sev_unlock_after_migration(struct kvm *kvm)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+
+ mutex_unlock(&kvm->lock);
+ atomic_set_release(&sev->migration_in_progress, 0);
+}
+
+
+static int sev_lock_vcpus_for_migration(struct kvm *kvm)
+{
+ struct kvm_vcpu *vcpu;
+ int i, j;
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ if (mutex_lock_killable(&vcpu->mutex))
+ goto out_unlock;
+ }
+
+ return 0;
+
+out_unlock:
+ kvm_for_each_vcpu(j, vcpu, kvm) {
+ if (i == j)
+ break;
+
+ mutex_unlock(&vcpu->mutex);
+ }
+ return -EINTR;
+}
+
+static void sev_unlock_vcpus_for_migration(struct kvm *kvm)
+{
+ struct kvm_vcpu *vcpu;
+ int i;
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ mutex_unlock(&vcpu->mutex);
+ }
+}
+
+static void sev_migrate_from(struct kvm_sev_info *dst,
+ struct kvm_sev_info *src)
+{
+ dst->active = true;
+ dst->asid = src->asid;
+ dst->handle = src->handle;
+ dst->pages_locked = src->pages_locked;
+
+ src->asid = 0;
+ src->active = false;
+ src->handle = 0;
+ src->pages_locked = 0;
+
+ if (dst->misc_cg != src->misc_cg)
+ sev_misc_cg_uncharge(src);
+
+ put_misc_cg(src->misc_cg);
+ src->misc_cg = NULL;
+
+ INIT_LIST_HEAD(&dst->regions_list);
+ list_replace_init(&src->regions_list, &dst->regions_list);
+}
+
+int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd)
+{
+ struct kvm_sev_info *dst_sev = &to_kvm_svm(kvm)->sev_info;
+ struct kvm_sev_info *src_sev;
+ struct file *source_kvm_file;
+ struct kvm *source_kvm;
+ 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;
+ goto out_fput;
+ }
+
+ source_kvm = source_kvm_file->private_data;
+ ret = sev_lock_for_migration(source_kvm);
+ if (ret)
+ goto out_fput;
+
+ if (!sev_guest(source_kvm) || sev_es_guest(source_kvm)) {
+ ret = -EINVAL;
+ goto out_source;
+ }
+
+ src_sev = &to_kvm_svm(source_kvm)->sev_info;
+ dst_sev->misc_cg = get_current_misc_cg();
+ if (dst_sev->misc_cg != src_sev->misc_cg) {
+ ret = sev_misc_cg_try_charge(dst_sev);
+ if (ret)
+ goto out_dst_put_cgroup;
+ }
+
+ ret = sev_lock_vcpus_for_migration(kvm);
+ if (ret)
+ goto out_dst_cgroup;
+ ret = sev_lock_vcpus_for_migration(source_kvm);
+ if (ret)
+ goto out_dst_vcpu;
+
+ sev_migrate_from(dst_sev, src_sev);
+ kvm_vm_dead(source_kvm);
+ ret = 0;
+
+ sev_unlock_vcpus_for_migration(source_kvm);
+out_dst_vcpu:
+ sev_unlock_vcpus_for_migration(kvm);
+out_dst_cgroup:
+ if (ret < 0) {
+ sev_misc_cg_uncharge(dst_sev);
+out_dst_put_cgroup:
+ put_misc_cg(dst_sev->misc_cg);
+ dst_sev->misc_cg = NULL;
+ }
+out_source:
+ sev_unlock_after_migration(source_kvm);
+out_fput:
+ if (source_kvm_file)
+ fput(source_kvm_file);
+out_unlock:
+ sev_unlock_after_migration(kvm);
+ return ret;
+}
+
int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
{
struct kvm_sev_cmd sev_cmd;
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 1143b4ac900d36c9bf7619e6c63b66f7a9020121..b4f2d1d55bd2151be44b7f5f042197adac9d1ebc 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4699,6 +4699,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
.mem_enc_unreg_region = svm_unregister_enc_region,
.vm_copy_enc_context_from = svm_vm_copy_asid_from,
+ .vm_move_enc_context_from = svm_vm_migrate_from,
.can_emulate_instruction = svm_can_emulate_instruction,
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 80048841cad9bcfe4ff22fbe62bcb13d656dcbbe..d4eae06b069538a6e8a5707e72510d0879aa7abc 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -80,6 +80,7 @@ struct kvm_sev_info {
u64 ap_jump_table; /* SEV-ES AP Jump Table address */
struct kvm *enc_context_owner; /* Owner of copied encryption context */
struct misc_cg *misc_cg; /* For misc cgroup accounting */
+ atomic_t migration_in_progress;
};
struct kvm_svm {
@@ -562,6 +563,7 @@ int svm_register_enc_region(struct kvm *kvm,
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);
+int svm_vm_migrate_from(struct kvm *kvm, unsigned int source_fd);
void pre_sev_run(struct vcpu_svm *svm, int cpu);
void __init sev_set_cpu_caps(void);
void __init sev_hardware_setup(void);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 622cb75f5e752af75db83381bdad17dec7264b43..4417f375da7720b6c77ef9c4cf2811f01452821d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5845,6 +5845,12 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
if (kvm_x86_ops.vm_copy_enc_context_from)
r = kvm_x86_ops.vm_copy_enc_context_from(kvm, cap->args[0]);
return r;
+ case KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM:
+ r = -EINVAL;
+ if (kvm_x86_ops.vm_move_enc_context_from)
+ r = kvm_x86_ops.vm_move_enc_context_from(
+ kvm, cap->args[0]);
+ return r;
case KVM_CAP_EXIT_HYPERCALL:
if (cap->args[0] & ~KVM_EXIT_HYPERCALL_VALID_MASK) {
r = -EINVAL;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 78f0719cc2a3a2f315de7b970cbcfb7ec5a3a256..1daa45268de266ce9b71fbe6470a362cb4d482f6 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1130,6 +1130,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_BINARY_STATS_FD 203
#define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204
#define KVM_CAP_ARM_MTE 205
+#define KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM 206
#ifdef KVM_CAP_IRQ_ROUTING