@@ -6701,6 +6701,21 @@ 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_MIGRATE_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.
+in-guest workloads scheduled by the host. This allows for upgrading the VMM
+process without interrupting the guest.
+
8. Other capabilities.
======================
@@ -1448,6 +1448,7 @@ 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_migrate_enc_context_from)(struct kvm *kvm, unsigned int source_fd);
int (*get_msr_feature)(struct kvm_msr_entry *entry);
@@ -1501,6 +1501,105 @@ static int sev_receive_finish(struct kvm *kvm, struct kvm_sev_cmd *argp)
return sev_issue_cmd(kvm, SEV_CMD_RECEIVE_FINISH, &data, &argp->error);
}
+static int svm_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 svm_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 void migrate_info_from(struct kvm_sev_info *dst,
+ struct kvm_sev_info *src)
+{
+ sev_asid_free(dst);
+
+ dst->asid = src->asid;
+ dst->misc_cg = src->misc_cg;
+ dst->handle = src->handle;
+ dst->pages_locked = src->pages_locked;
+
+ src->asid = 0;
+ src->active = false;
+ src->handle = 0;
+ src->pages_locked = 0;
+ 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 file *source_kvm_file;
+ struct kvm *source_kvm;
+ int ret;
+
+ ret = svm_sev_lock_for_migration(kvm);
+ if (ret)
+ return ret;
+
+ if (!sev_guest(kvm) || sev_es_guest(kvm)) {
+ ret = -EINVAL;
+ pr_warn_ratelimited("VM must be SEV enabled to migrate to.\n");
+ goto out_unlock;
+ }
+
+ if (!list_empty(&dst_sev->regions_list)) {
+ ret = -EINVAL;
+ pr_warn_ratelimited(
+ "VM must not have encrypted regions to migrate to.\n");
+ 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 = svm_sev_lock_for_migration(source_kvm);
+ if (ret)
+ goto out_fput;
+
+ if (!sev_guest(source_kvm) || sev_es_guest(source_kvm)) {
+ ret = -EINVAL;
+ pr_warn_ratelimited(
+ "Source VM must be SEV enabled to migrate from.\n");
+ goto out_source;
+ }
+
+ migrate_info_from(dst_sev, &to_kvm_svm(source_kvm)->sev_info);
+ ret = 0;
+
+out_source:
+ svm_unlock_after_migration(source_kvm);
+out_fput:
+ if (source_kvm_file)
+ fput(source_kvm_file);
+out_unlock:
+ svm_unlock_after_migration(kvm);
+ return ret;
+}
+
int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
{
struct kvm_sev_cmd sev_cmd;
@@ -4627,6 +4627,7 @@ 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_migrate_enc_context_from = svm_vm_migrate_from,
.can_emulate_instruction = svm_can_emulate_instruction,
@@ -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 {
@@ -552,6 +553,7 @@ 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);
@@ -5655,6 +5655,11 @@ 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_MIGRATE_ENC_CONTEXT_FROM:
+ r = -EINVAL;
+ if (kvm_x86_ops.vm_migrate_enc_context_from)
+ r = kvm_x86_ops.vm_migrate_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;
@@ -1112,6 +1112,7 @@ 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_MIGRATE_ENC_CONTEXT_FROM 206
#ifdef KVM_CAP_IRQ_ROUTING
For SEV to work with intra host migration, contents of the SEV info struct such as the ASID (used to index the encryption key in the AMD SP) and the list of memory regions need to be transferred to the target VM. This change adds a commands for a target VMM to get a source SEV VM's sev info. The target is expected to be initialized (sev_guest_init), but not launched state (sev_launch_start) when performing receive. Once the target has received, it will be in a launched state and will not need to perform the typical SEV launch commands. Signed-off-by: Peter Gonda <pgonda@google.com> Suggested-by: Sean Christopherson <seanjc@google.com> Cc: Marc Orr <marcorr@google.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Sean Christopherson <seanjc@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Wanpeng Li <wanpengli@tencent.com> Cc: Jim Mattson <jmattson@google.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- Documentation/virt/kvm/api.rst | 15 +++++ arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/svm/sev.c | 99 +++++++++++++++++++++++++++++++++ arch/x86/kvm/svm/svm.c | 1 + arch/x86/kvm/svm/svm.h | 2 + arch/x86/kvm/x86.c | 5 ++ include/uapi/linux/kvm.h | 1 + 7 files changed, 124 insertions(+)