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23 Nov 2022 08:41:25 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10540"; a="816537366" X-IronPort-AV: E=Sophos;i="5.96,187,1665471600"; d="scan'208";a="816537366" Received: from vcbudden-mobl3.amr.corp.intel.com (HELO [10.212.129.67]) ([10.212.129.67]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Nov 2022 08:41:24 -0800 Message-ID: <168ca2b3-ffac-31c4-0b83-2d0ee75f34a5@intel.com> Date: Wed, 23 Nov 2022 08:41:22 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCH v7 06/20] x86/virt/tdx: Shut down TDX module in case of error Content-Language: en-US To: Sean Christopherson , "Huang, Kai" Cc: "peterz@infradead.org" , "kvm@vger.kernel.org" , "Luck, Tony" , "bagasdotme@gmail.com" , "ak@linux.intel.com" , "Wysocki, Rafael J" , "linux-kernel@vger.kernel.org" , "Chatre, Reinette" , "pbonzini@redhat.com" , "linux-mm@kvack.org" , "Yamahata, Isaku" , "kirill.shutemov@linux.intel.com" , "Shahar, Sagi" , "imammedo@redhat.com" , "Gao, Chao" , "Brown, Len" , "sathyanarayanan.kuppuswamy@linux.intel.com" , "Huang, Ying" , "Williams, Dan J" References: <48505089b645019a734d85c2c29f3c8ae2dbd6bd.1668988357.git.kai.huang@intel.com> <52b2be9b-defd-63ce-4cb2-96cd624a95a6@intel.com> <791bf9a2-a079-3cd6-90a3-42dbb332a38c@intel.com> <9f1ea2639839305dd8b82694b3d8c697803f43a1.camel@intel.com> From: Dave Hansen In-Reply-To: Content-Type: text/plain; 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bh=JRnIEisbgsyDRlXpDM5B9Rn006OUSMO2TsaMa27UJCs=; b=F95ujkclBALVA9yMC0YLTfyY/eqVXKnHplmpERIiSXK2aPT52yDx0ArNHZ9AWorTVD7sfP zjaNVgfYadCv4CWlQXDWemndcJ/mKrcQc7/7Rs0oUKFI/V9RapbkRzsGEYUii3La2XmiCq lRrA/QWPtXyhwhZpucIYFT3JxGGT/Ns= X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 31197A0010 Authentication-Results: imf25.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b="mt/649Hc"; spf=pass (imf25.hostedemail.com: domain of dave.hansen@intel.com designates 192.55.52.115 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspam-User: X-Stat-Signature: mfeb5a15rw36fb518gdu4x9kg95fxipp X-HE-Tag: 1669221686-552343 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 11/23/22 08:20, Sean Christopherson wrote: >>> Why is it done that way? >>> >>> Can it be changed to delay TDX initialization until the first TDX guest >>> needs to run? >>> >> Sean suggested. >> >> Hi Sean, could you commenet? > Waiting until the first TDX guest is created would result in false advertising, > as KVM wouldn't know whether or not TDX is actually supported until that first > VM is created. If we can guarantee that TDH.SYS.INIT will fail if and only if > there is a kernel bug, then I would be ok deferring the "enabling" until the > first VM is created. There's no way we can guarantee _that_. For one, the PAMT* allocations can always fail. I guess we could ask sysadmins to fire up a guest to "prime" things, but that seems a little silly. Maybe that would work as the initial implementation that we merge, but I suspect our users will demand more determinism, maybe a boot or module parameter. * Physical Address Metadata Table, a large physically contiguous data structure, the rough equivalent of 'struct page' for the TDX module