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X-CSE-ConnectionGUID: 0rgyKWE6TAi7pSs1x8qXoA== X-CSE-MsgGUID: jIiGXMUnQt2jbTjuq4EKJg== X-IronPort-AV: E=McAfee;i="6800,10657,11820"; a="86545390" X-IronPort-AV: E=Sophos;i="6.24,211,1774335600"; d="scan'208";a="86545390" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jun 2026 08:05:00 -0700 X-CSE-ConnectionGUID: 9kUffgg9Scy/8SUvatPtOA== X-CSE-MsgGUID: ebaT3CgCT0yxru2RWbcQpw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,211,1774335600"; d="scan'208";a="248465617" Received: from rfrazer-mobl3.amr.corp.intel.com (HELO [10.125.111.222]) ([10.125.111.222]) by orviesa009-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jun 2026 08:04:59 -0700 Message-ID: <4f4b0f29-424b-45ed-8cfd-c77da2ea390f@intel.com> Date: Thu, 18 Jun 2026 08:04:58 -0700 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 02/17] x86/virt/tdx: Configure add-on features on TDX module init and update To: Xu Yilun , x86@kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org Cc: djbw@kernel.org, kas@kernel.org, rick.p.edgecombe@intel.com, 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, dave.hansen@linux.intel.com, seanjc@google.com References: <20260618081355.3253581-1-yilun.xu@linux.intel.com> <20260618081355.3253581-3-yilun.xu@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 6/18/26 01:13, Xu Yilun wrote: > int tdx_module_run_update(void) > { > + u64 seamcall_fn = TDH_SYS_UPDATE_V0; > struct tdx_module_args args = {}; > int ret; > > - ret = seamcall_prerr(TDH_SYS_UPDATE, &args); > + if (tdx_addon_feature0) { > + args.r9 = tdx_addon_feature0; > + seamcall_fn = TDH_SYS_UPDATE; > + } Heh, and it falls apart into craziness immediately. See how it immediately loses the logical information that there's a version 1 and a version 0? The "1" isn't even visible. It's hidden in "TDH_SYS_UPDATE". Isn't this a million times more sane? struct tdx_module_args args = {}; u64 version; int ret; if (tdx_addon_feature0) { args.r9 = tdx_addon_feature0; version = 1; } else { version = 0; } ret = seamcall_prerr(TDH_SYS_UPDATE, version, &args); There's also zero stopping us from putting version in args: struct tdx_module_args args = {}; int ret; if (tdx_addon_feature0) { args.r9 = tdx_addon_feature0; args.version = 1; } ret = seamcall_prerr(TDH_SYS_UPDATE, &args); Eh? That gives args.version==0 in all the normal cases which just happens to be the exact behavior we want. It also avoids having to plumb version through all the seamcall*() wrappers. But this is *exactly* the kind of thing that shouldn't be a part of an attestation patch series. This could very much have been a separate discussion and happened a month or a year ago. But now it is blocking this DICE thing from getting done .