From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 871EAB67E; Thu, 29 Jan 2026 00:08:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769645340; cv=none; b=AgorBcRxE1S5Xu2Wt7eqxVvhj8M4rtWodkmwIte9p8NWKGq/mnVJ643UZpjwtAEzrhI17n+PfXob8Nq4E4MCvY0Jg1Yw4IxqECMcga3ZPN5iUDFlPAMoIGZcS9tN+hbLx09qmklaf+0AefP1Gmv+dIah982So5+Box3BUVFI9Jg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769645340; c=relaxed/simple; bh=9LYr8Fxu212VdsYBhWkSdj37mqiggQ5RrjlkUbQdIxU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qDLiClX4jbPJI3EjUWWV3eersdajgVrQimQWgKQ471QqIlcrZyLh0hxyRJVQuRcSRPXiI8P0PXQki9BGNDnWVndYd99g4YkKe0tTiKyqHpHog3kjdCBE9cBI50hxFrc3onnJZm2vrd6JwNnUhnmZULB9zpyg0+WKHCllvEG8aqQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=N6KAbIop; arc=none smtp.client-ip=198.175.65.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="N6KAbIop" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1769645339; x=1801181339; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=9LYr8Fxu212VdsYBhWkSdj37mqiggQ5RrjlkUbQdIxU=; b=N6KAbIop3OIm/k/1ktGVUOwNREsED9527zUUAOy9Bkzuu0O2zJsXmTfE PDssyMccHpJJuZ+xN0r5IlJmTeHOQQiQL1THMM8GF9+5RfITTbtlmpjRz O9TJW7b7vNp3I4KnvQxYGyvVK9brubMVBPlLzmmjY87KvVk0SOSX2Fn6H 047JlSKKnN8P8i7ZOqcFRORmYVXko6oHEZonB1PbuFlNk8//KrdezS5Fz 7bVsiAzT+sxTFarjyPXop+Uya/mEEuuN0UjjLZiGx7lmSk0qhC3o/U2ay 0CLmkjLNCyuK1jk6Q8qlr7LSiqDqy7x82kqwqiGPLlakYYpNX4iRq3ifh g==; X-CSE-ConnectionGUID: vuAe4/B6Sq2myvJjyCVpgw== X-CSE-MsgGUID: oZz31BrRSaS1BlSUduaU9Q== X-IronPort-AV: E=McAfee;i="6800,10657,11685"; a="70846504" X-IronPort-AV: E=Sophos;i="6.21,258,1763452800"; d="scan'208";a="70846504" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by orvoesa109.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Jan 2026 16:08:58 -0800 X-CSE-ConnectionGUID: zbavyxq5QbGi7CH5NYz7pg== X-CSE-MsgGUID: VsJfNMmzS+6Euqw96iQTyg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,258,1763452800"; d="scan'208";a="208008127" Received: from kcaccard-desk.amr.corp.intel.com (HELO [10.125.109.190]) ([10.125.109.190]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Jan 2026 16:08:57 -0800 Message-ID: <9fb1bbf3-0623-447e-86d7-d48ef20fb42c@intel.com> Date: Wed, 28 Jan 2026 16:08:56 -0800 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 v3 09/26] coco/tdx-host: Expose P-SEAMLDR information via sysfs To: Chao Gao , linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org Cc: reinette.chatre@intel.com, ira.weiny@intel.com, kai.huang@intel.com, dan.j.williams@intel.com, yilun.xu@linux.intel.com, sagis@google.com, vannapurve@google.com, paulmck@kernel.org, nik.borisov@suse.com, zhenzhong.duan@intel.com, seanjc@google.com, rick.p.edgecombe@intel.com, kas@kernel.org, dave.hansen@linux.intel.com, vishal.l.verma@intel.com, Farrah Chen References: <20260123145645.90444-1-chao.gao@intel.com> <20260123145645.90444-10-chao.gao@intel.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: <20260123145645.90444-10-chao.gao@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 1/23/26 06:55, Chao Gao wrote: ... > diff --git a/Documentation/ABI/testing/sysfs-devices-faux-tdx-host b/Documentation/ABI/testing/sysfs-devices-faux-tdx-host > index 901abbae2e61..a3f155977016 100644 > --- a/Documentation/ABI/testing/sysfs-devices-faux-tdx-host > +++ b/Documentation/ABI/testing/sysfs-devices-faux-tdx-host > @@ -4,3 +4,28 @@ Description: (RO) Report the version of the loaded TDX Module. The TDX Module > version is formatted as x.y.z, where "x" is the major version, > "y" is the minor version and "z" is the update version. Versions > are used for bug reporting, TDX Module updates and etc. > + > +What: /sys/devices/faux/tdx_host/seamldr/version > +Contact: linux-coco@lists.linux.dev > +Description: (RO) Report the version of the loaded SEAM loader. The SEAM > + loader version is formatted as x.y.z, where "x" is the major > + version, "y" is the minor version and "z" is the update version. > + Versions are used for bug reporting and compatibility check. checks ^ > +What: /sys/devices/faux/tdx_host/seamldr/num_remaining_updates > +Contact: linux-coco@lists.linux.dev > +Description: (RO) Report the number of remaining updates that can be performed. > + The CPU keeps track of TCB versions for each TDX Module that > + has been loaded. Since this tracking database has finite > + capacity, there's a maximum number of Module updates that can > + be performed. Is it really the CPU? Or some SEAM software construct? > + After each successful update, the number reduces by one. Once it > + reaches zero, further updates will fail until next reboot. The > + number is always zero if P-SEAMLDR doesn't support updates. > + > + See Intel® Trust Domain Extensions - SEAM Loader (SEAMLDR) > + Interface Specification Chapter 3.3 "SEAMLDR_INFO" and Chapter > + 4.2 "SEAMLDR.INSTALL" for more information. The documentation is > + available at: > + https://cdrdv2-public.intel.com/739045/intel-tdx-seamldr-interface-specification.pdf Zap the URL. It's just going bit rot. Keep the document name. That's googleable. > diff --git a/drivers/virt/coco/tdx-host/tdx-host.c b/drivers/virt/coco/tdx-host/tdx-host.c > index 0424933b2560..f4ce89522806 100644 > --- a/drivers/virt/coco/tdx-host/tdx-host.c > +++ b/drivers/virt/coco/tdx-host/tdx-host.c > @@ -11,6 +11,7 @@ > #include > > #include > +#include > #include > > static const struct x86_cpu_id tdx_host_ids[] = { > @@ -40,7 +41,64 @@ static struct attribute *tdx_host_attrs[] = { > &dev_attr_version.attr, > NULL, > }; > -ATTRIBUTE_GROUPS(tdx_host); > + > +struct attribute_group tdx_host_group = { > + .attrs = tdx_host_attrs, > +}; > + > +#ifdef CONFIG_INTEL_TDX_MODULE_UPDATE > +static ssize_t seamldr_version_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + const struct seamldr_info *info = seamldr_get_info(); Uhh... seamldr_get_info() calls down into the SEAMLDR. It happily zaps the VMCS and this is surely a slow thing. This also has 0444 permissions which means *ANYONE* can call this. Constantly. As fast as they can make a few syscalls. Right? Are there any concerns about making SEAMLDR calls? Are there any system-wide performance implications? How long of an interrupt-blocking blip is there for this? Also, what's the locking around seamldr_get_info()? It writes into a global, shared structure. I guess you disabled interrupts so it's preempt safe at least. I guess it won't change *that* much. But, sheesh, it seems like an awfully bad idea to have lots of CPUs writing into a common data structure all at the same time.