Re: [RFC PATCH v2 1/4] Documentation: KVM: Add live migration API for confidential guests

[Artem Bityutskiy <artem.bityutskiy@linux.intel.com>]

On Mon, 2026-08-31 at 10:13 +0300, Tony Lindgren wrote:

> +  /**
> +   * @command: One of the defined KVM_MIGRATE commands
> +   * @flags: Hardware specific flags
> +   * @reserved: Reserved for future use
> +   * @buf: Userspace buffer for hardware specific data
> +   */
> +  struct kvm_migrate_cmd {
> +	__u16 command;
> +	__u16 flags;
> +	__u32 reserved;
> +	struct kvm_transfer_buffer buf;
> +  };

I think everything should be _u64. And there should be something like

__u64 reserved[14];

with a requirement to be set to 0. This may be useful for possible future
extensions.

Rationale: If the system can afford CoCo VMs and their live migration,
this must be a relatively powerful system, 64-bit today, where we do
not need to save memory by using __u16 and __u32 and not adding extra
reserved space.

Thanks,
Artem.