Re: [RFC PATCH v2 2/4] KVM: x86: Add optional KVM_CAP_LIVE_MIGRATION and KVM_MIGRATE_CMD

[Tony Lindgren <tony.lindgren@linux.intel.com>]

On Mon, Aug 31, 2026 at 10:13:02AM +0300, Tony Lindgren wrote:
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1670,4 +1673,23 @@ struct kvm_pre_fault_memory {
>  	__u64 padding[5];
>  };
>  
> +#define KVM_MIGRATE_SETUP		0
> +#define KVM_MIGRATE_ITERATION		1
> +#define KVM_MIGRATE_STOP_AND_COPY	2
> +#define KVM_MIGRATE_ABORT		3
> +#define KVM_MIGRATE_END			4
> +
> +struct kvm_transfer_buffer {
> +	__u64 address;
> +	__u32 size;
> +	__u32 reserved;
> +};
> +
> +struct kvm_migrate_cmd {
> +	__u16 command;
> +	__u16 flags;
> +	__u32 reserved;
> +	struct kvm_transfer_buffer buf;
> +};

For the common flags, KVM_MIGRATE_CMD probably should have migration
direction. Or maybe we could have KVM_EXPORT_CMD and KVM_IMPORT_CMD.

The migration direction is needed early for TDX. We currently pass a flag
for delayed init for the migration destination in KVM_TDX_INIT_VM. This
is to prevent the TD and vCPU init SEAMCALLs on the destination. The TD
and vCPU are initialized only later on with the import calls.