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a="3095602" X-IronPort-AV: E=Sophos;i="6.27,205,1787036400"; d="scan'208";a="3095602" Received: from fmviesa013.fm.intel.com ([10.60.135.153]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Nov 2026 04:42:31 -0800 X-CSE-ConnectionGUID: cDYGt7P7QhOMvZa6p8q2DQ== X-CSE-MsgGUID: hQnKdKpoS3iW7yzNUmBOyQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,205,1787036400"; d="scan'208";a="10008643" Received: from linux.intel.com ([10.54.29.200]) by fmviesa013.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Nov 2026 04:42:31 -0800 Received: from [10.245.245.51] (abityuts-desk1.ger.corp.intel.com [10.245.245.51]) by linux.intel.com (Postfix) with ESMTP id D0E3F20B8CD1; Tue, 10 Nov 2026 04:42:23 -0800 (PST) Message-ID: <61437761ac1bbdf10204084c08a066ee6168feca.camel@linux.intel.com> Subject: Re: [RFC PATCH v2 1/4] Documentation: KVM: Add live migration API for confidential guests From: Artem Bityutskiy To: Tony Lindgren , Paolo Bonzini , Sean Christopherson Cc: Peter Xu , Fabiano Rosas , Jon Grimm , Pankaj Gupta , Tom Lendacky , Marc Zyngier , Oliver Upton , Steven Price , Anup Patel , Samuel Ortiz , Jakub =?UTF-8?Q?R=C5=AF=C5=BEi=C4=8Dka?= , =?ISO-8859-1?Q?J=F6rg_R=F6del?= , Vishal Annapurve , Elena Reshetova , Kai Huang , Kishen Maloor , Mika Westerberg , Peter Fang , Rick Edgecombe , Xiaoyao Li , Xu Yilun , kvm@vger.kernel.org Date: Tue, 10 Nov 2026 14:42:22 +0200 In-Reply-To: <20260831071304.762939-2-tony.lindgren@linux.intel.com> References: <20260831071304.762939-1-tony.lindgren@linux.intel.com> <20260831071304.762939-2-tony.lindgren@linux.intel.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 (3.60.2-3.fc44) X-Mailing-List: kvm@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 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.