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X-CSE-ConnectionGUID: FnjqrzJZSCuJa9E4vAYKVQ== X-CSE-MsgGUID: VmXMGJIGTUepavq+2dxXaA== X-IronPort-AV: E=McAfee;i="6800,10657,11935"; a="844968" X-IronPort-AV: E=Sophos;i="6.27,158,1787036400"; d="scan'208";a="844968" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by orvoesa113.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Oct 2026 08:59:33 -0700 X-CSE-ConnectionGUID: UafhCUUaRrCB88B2XL5vaw== X-CSE-MsgGUID: wLbJRdF5Qs2oOZwrJxweCQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,158,1787036400"; d="scan'208";a="1797720" Received: from aschende-mobl.amr.corp.intel.com (HELO [10.125.110.30]) ([10.125.110.30]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Oct 2026 08:59:32 -0700 Message-ID: Date: Wed, 14 Oct 2026 08:59:32 -0700 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 1/6] x86/virt/tdx: Move TDH.SYS.CONFIG operations into a wrapper To: Xu Yilun , x86@kernel.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org Cc: Kiryl Shutsemau , Rick Edgecombe , Dave Hansen , kvm@vger.kernel.org, yilun.xu@intel.com, xiaoyao.li@intel.com, sohil.mehta@intel.com, adrian.hunter@intel.com, kishen.maloor@intel.com, tony.lindgren@linux.intel.com, peter.fang@intel.com, baolu.lu@linux.intel.com, zhenzhong.duan@intel.com, chao.gao@intel.com, artem.bityutskiy@linux.intel.com, nik.borisov@suse.com References: <20261013-tdx-module-ext-v4-0-de5ffac65470@linux.intel.com> <20261013-tdx-module-ext-v4-1-de5ffac65470@linux.intel.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/13/26 08:28, Xu Yilun wrote: > SEAMCALL wrappers are introduced to avoid broad SEAMCALL access by > exposing only a selection of SEAMCALL leafs, but also to abstract the > SEAMCALL register ABIs. The abstraction improves readability and reuse > for SEAMCALL leafs that are called multiple times. > > Some SEAMCALL leafs are not explicitly wrapped because the level of TDX > ABI details needed to perform the call is low enough to flow well with > the calling code. > > For some of the currently unwrapped SEAMCALL leafs, the TDX architecture > has evolved the ABI to introduce new leaf versions. The host can select > the version to call based on what is supported by the loaded TDX module. > When future kernel implements this version selection, more ABI details > will leak into the surrounding caller code, which decreases the > readability of the caller logic. To keep the ABI details contained, move > the SEAMCALL leaf that will need version selection into a wrapper. > > When defining the wrapper, the cleanest separation would be to have > kernel data types for the SEAMCALL wrapper arguments, and have them > marshaled into SEAMCALL leaf ABI types (often u64s) inside the wrapper. > This works for many SEAMCALL leafs but becomes cumbersome when the > register ABI type is a physical address which points to a buffer for an > in-memory ABI. If the SEAMCALL wrapper only accepts kernel data types, > it may need duplicate buffer allocation and copies to match the > in-memory ABI. Another solution is to define a named helper structure > that mirrors the in-memory ABI, populate it in a separate flow, then > pass it to the SEAMCALL wrapper. struct seamldr_params is an existing > example of this pattern. > > TDH.SYS.CONFIG requires a list of TDMR information in the form of a PA > array. The PA array is the in-memory ABI. Create a structure for the PA > array, use it as the argument when creating the wrapper for > TDH.SYS.CONFIG. > > For readability, adjust a bit of the existing PA array size calculation: > use the new PA array structure's element type instead of hardcoding u64. > > AI was used under supervision to review code and workshop logs. I'm wondering if this is a case of AI gone wild. There's a *LOT* of info there, but I'm not seeing the thing I really want to see: Why is it worth creating this helper _now_? Also, the move to tdmr_info_pa_array seems 100% orthogonal to me. Why is it here?