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

[Zhi Wang <zhi.wang.linux@gmail.com>]

On Fri,  7 Apr 2023 20:19:19 +0000
Sagi Shahar <sagis@google.com> wrote:

Is there any reaon that TDX doesn't need .vm_copy_enc_context_from? Or it is
going to be deprecated? The patch comments needs to be refined according to
Sean's KVM x86 maintainer book.

> 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)