From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (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 C7CD72D8799; Wed, 28 Jan 2026 23:36:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769643412; cv=none; b=Bze3HqNyaNMytQiQ+YuYZZCbvD9nmfmUqIzhCMPT79OKJiTeg0hoXjcVsfzIHhU9DjCLc+9gM8owtoAvtnRRL2JNM1GYzNp5ahZoYMyiv7XZ9XYuSp0TqUAMO8AyecJjCMt3Cuf3QN7HzyoeegZ8KiZ6lBMWMbHDqkMoQ0We4vY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769643412; c=relaxed/simple; bh=pY7pQJEOHa6B148FkxDEx/S3AddhuNgnzB//YrudAAU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gtv8qsaFRWF227IIbZRiBuHTQ/DsyixCd2HvLlsf0KowQoeJcpQQFw0sH68zTiVAGc42QL/dKarhOZofuNoS7zHFj/nfbeB81T7FBtOC1tNBRzCrkWkHIS69OVE+YUqrN+V9IisMQC/9elYGe4Wc8xZdhuJYYDc1HUP3lYuiB+4= 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=QV9+uh43; arc=none smtp.client-ip=192.198.163.19 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="QV9+uh43" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1769643410; x=1801179410; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=pY7pQJEOHa6B148FkxDEx/S3AddhuNgnzB//YrudAAU=; b=QV9+uh43wsiX4YZuxxcjWu3zUWJRUtfW+PMFZJD2vNT5cL9/6+deDxu/ NX7YBtbhyUG6UjgtlcLNlzcQaTgufh+TNTLWMgdjRbOnO7vcNQsrsNrYe bQboezth11hHM5WQ5nEhL2L6c1twXDCaLIfpT6ovNOWO6h3t45BDSAOQO maLGyT0tB+iLQIuW+YayxbgJYbW1zVKCzOM81V6Fn2aDnSf2FCC8xcvn2 zHZB7WfcHNKs3FCd+41ItoBgCSYIAeTzuoJHQ4i1PPeXyuWGe//I2Mo5o Vvbx2Dzwk0894jYNdBKLZ+k48PjOz7so+9psU1wlCMN82247OTFHVy0Gk g==; X-CSE-ConnectionGUID: sUZrFg6GTo6FG/rYrSJHqQ== X-CSE-MsgGUID: qlttQNEZTkKPj3Q8e845/A== X-IronPort-AV: E=McAfee;i="6800,10657,11685"; a="69885831" X-IronPort-AV: E=Sophos;i="6.21,258,1763452800"; d="scan'208";a="69885831" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Jan 2026 15:36:50 -0800 X-CSE-ConnectionGUID: bdIAQWIBQo6uLK9IaPzH0w== X-CSE-MsgGUID: 16c0GeNwRfOZszGx9ogCUg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,258,1763452800"; d="scan'208";a="208424267" Received: from kcaccard-desk.amr.corp.intel.com (HELO [10.125.109.190]) ([10.125.109.190]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Jan 2026 15:36:49 -0800 Message-ID: <301f8156-bafe-440a-8628-3bf8fae74464@intel.com> Date: Wed, 28 Jan 2026 15:36:49 -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 07/26] x86/virt/seamldr: Introduce a wrapper for P-SEAMLDR SEAMCALLs 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 , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" References: <20260123145645.90444-1-chao.gao@intel.com> <20260123145645.90444-8-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: <20260123145645.90444-8-chao.gao@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/23/26 06:55, Chao Gao wrote: ... > +static __maybe_unused int seamldr_call(u64 fn, struct tdx_module_args *args) > +{ > + unsigned long flags; > + u64 vmcs; > + int ret; > + > + if (!is_seamldr_call(fn)) > + return -EINVAL; Why is this here? We shouldn't be silently papering over kernel bugs. This is a WARN_ON() at *best*, but it also begs the question of how a non-SEAMLDR call even got here. > + /* > + * SEAMRET from P-SEAMLDR invalidates the current VMCS. Save/restore > + * the VMCS across P-SEAMLDR SEAMCALLs to avoid clobbering KVM state. > + * Disable interrupts as KVM is allowed to do VMREAD/VMWRITE in IRQ > + * context (but not NMI context). > + */ I think you mean: WARN_ON(in_nmi()); > + local_irq_save(flags); > + > + asm goto("1: vmptrst %0\n\t" > + _ASM_EXTABLE(1b, %l[error]) > + : "=m" (vmcs) : : "cc" : error); I'd much rather this be wrapped up in a helper function. We shouldn't have to look at the horrors of inline assembly like this. But this *REALLY* wants the KVM folks to look at it. One argument is that with the inline assembly this is nice and self-contained. The other argument is that this completely ignores all existing KVM infrastructure and is parallel VMCS management. I'd be shocked if this is the one and only place in the whole kernel that can unceremoniously zap VMX state. I'd *bet* that you don't really need to do the vmptrld and that KVM can figure it out because it can vmptrld on demand anyway. Something along the lines of: local_irq_disable(); list_for_each(handwaving...) vmcs_clear(); ret = seamldr_prerr(fn, args); local_irq_enable(); Basically, zap this CPU's vmcs state and then make KVM reload it at some later time. I'm sure Sean and Paolo will tell me if I'm crazy. > diff --git a/drivers/virt/coco/tdx-host/Kconfig b/drivers/virt/coco/tdx-host/Kconfig > index e58bad148a35..6a9199e6c2c6 100644 > --- a/drivers/virt/coco/tdx-host/Kconfig > +++ b/drivers/virt/coco/tdx-host/Kconfig > @@ -8,3 +8,13 @@ config TDX_HOST_SERVICES > > Say y or m if enabling support for confidential virtual machine > support (CONFIG_INTEL_TDX_HOST). The module is called tdx_host.ko > + > +config INTEL_TDX_MODULE_UPDATE > + bool "Intel TDX module runtime update" > + depends on TDX_HOST_SERVICES > + help > + This enables the kernel to support TDX module runtime update. This > + allows the admin to update the TDX module to another compatible > + version without the need to terminate running TDX guests. ... as opposed to the method that the kernel has to update the module without terminating guests? ;) > + If unsure, say N. Let's call this: config INTEL_TDX_ONLY_DISABLE_THIS_IF_YOU_HATE_SECURITY_AND_IF_YOU_DO_WHY_ARE_YOU_RUNNING_TDX? Can we have question marks in config symbol names? ;) But, seriously, what the heck? Who would disable security updates for their confidential computing infrastructure? Is this some kind of intelligence test for our users so that if someone disables it we can just laugh at them?