[RFC PATCH 3/5] KVM: TDX: Add base implementation for tdx_vm_move_enc_context_from

[Sagi Shahar <sagis@google.com>]

This should mostly match the logic in sev_vm_move_enc_context_from.

Signed-off-by: Sagi Shahar <sagis@google.com>
---
 arch/x86/kvm/vmx/main.c    | 10 +++++++
 arch/x86/kvm/vmx/tdx.c     | 56 ++++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/vmx/tdx.h     |  2 ++
 arch/x86/kvm/vmx/x86_ops.h |  5 ++++
 4 files changed, 73 insertions(+)

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index 5b64fe5404958..9d5d0ac465bf6 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -979,6 +979,14 @@ static int vt_vcpu_mem_enc_ioctl(struct kvm_vcpu *vcpu, void __user *argp)
 	return tdx_vcpu_ioctl(vcpu, argp);
 }
 
+static int vt_move_enc_context_from(struct kvm *kvm, unsigned int source_fd)
+{
+	if (!is_td(kvm))
+		return -ENOTTY;
+
+	return tdx_vm_move_enc_context_from(kvm, source_fd);
+}
+
 #define VMX_REQUIRED_APICV_INHIBITS		       \
 (						       \
        BIT(APICV_INHIBIT_REASON_DISABLE)|	       \
@@ -1141,6 +1149,8 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 	.dev_mem_enc_ioctl = tdx_dev_ioctl,
 	.mem_enc_ioctl = vt_mem_enc_ioctl,
 	.vcpu_mem_enc_ioctl = vt_vcpu_mem_enc_ioctl,
+
+	.vm_move_enc_context_from = vt_move_enc_context_from,
 };
 
 struct kvm_x86_init_ops vt_init_ops __initdata = {
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 8af7e4e81c860..0999a6d827c99 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -2826,3 +2826,59 @@ int __init tdx_init(void)
 		INIT_LIST_HEAD(&per_cpu(associated_tdvcpus, cpu));
 	return 0;
 }
+
+static __always_inline bool tdx_guest(struct kvm *kvm)
+{
+	struct kvm_tdx *tdx_kvm = to_kvm_tdx(kvm);
+
+	return tdx_kvm->finalized;
+}
+
+static int tdx_migrate_from(struct kvm *dst, struct kvm *src)
+{
+	return -EINVAL;
+}
+
+int tdx_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd)
+{
+	struct kvm_tdx *dst_tdx = to_kvm_tdx(kvm);
+	struct file *src_kvm_file;
+	struct kvm_tdx *src_tdx;
+	struct kvm *src_kvm;
+	int ret;
+
+	src_kvm_file = fget(source_fd);
+	if (!file_is_kvm(src_kvm_file)) {
+		ret = -EBADF;
+		goto out_fput;
+	}
+	src_kvm = src_kvm_file->private_data;
+	src_tdx = to_kvm_tdx(src_kvm);
+
+	ret = pre_move_enc_context_from(kvm, src_kvm,
+					&dst_tdx->migration_in_progress,
+					&src_tdx->migration_in_progress);
+	if (ret)
+		goto out_fput;
+
+	if (tdx_guest(kvm) || !tdx_guest(src_kvm)) {
+		ret = -EINVAL;
+		goto out_post;
+	}
+
+	ret = tdx_migrate_from(kvm, src_kvm);
+	if (ret)
+		goto out_post;
+
+	kvm_vm_dead(src_kvm);
+	ret = 0;
+
+out_post:
+	post_move_enc_context_from(kvm, src_kvm,
+				 &dst_tdx->migration_in_progress,
+				 &src_tdx->migration_in_progress);
+out_fput:
+	if (src_kvm_file)
+		fput(src_kvm_file);
+	return ret;
+}
diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
index 71818c5001862..21b7e710be1fd 100644
--- a/arch/x86/kvm/vmx/tdx.h
+++ b/arch/x86/kvm/vmx/tdx.h
@@ -24,6 +24,8 @@ struct kvm_tdx {
 	atomic_t tdh_mem_track;
 
 	u64 tsc_offset;
+
+	atomic_t migration_in_progress;
 };
 
 union tdx_exit_reason {
diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index d049e0c72ed0c..275f5d75e9bf1 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -187,6 +187,8 @@ int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp);
 void tdx_flush_tlb(struct kvm_vcpu *vcpu);
 int tdx_sept_tlb_remote_flush(struct kvm *kvm);
 void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level);
+
+int tdx_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd);
 #else
 static inline int tdx_init(void) { return 0; };
 static inline int tdx_hardware_setup(struct kvm_x86_ops *x86_ops) { return -ENOSYS; }
@@ -241,6 +243,9 @@ static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { ret
 static inline void tdx_flush_tlb(struct kvm_vcpu *vcpu) {}
 static inline int tdx_sept_tlb_remote_flush(struct kvm *kvm) { return 0; }
 static inline void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level) {}
+
+static inline int tdx_vm_move_enc_context_from(struct kvm *kvm, u
+					       nsigned int source_fd) { return -EOPNOTSUPP; }
 #endif
 
 #if defined(CONFIG_INTEL_TDX_HOST) && defined(CONFIG_KVM_SMM)
-- 
2.40.0.348.gf938b09366-goog