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X-IronPort-AV: E=McAfee;i="6600,9927,10734"; a="346762803" X-IronPort-AV: E=Sophos;i="6.00,225,1681196400"; d="scan'208";a="346762803" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jun 2023 17:29:57 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10734"; a="779664634" X-IronPort-AV: E=Sophos;i="6.00,225,1681196400"; d="scan'208";a="779664634" Received: from vsmyers-mobl2.amr.corp.intel.com (HELO [10.212.146.233]) ([10.212.146.233]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jun 2023 17:29:56 -0700 Message-ID: Date: Wed, 7 Jun 2023 17:29:55 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH v11 06/20] x86/virt/tdx: Handle SEAMCALL running out of entropy error Content-Language: en-US To: "Huang, Kai" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Cc: "Luck, Tony" , "david@redhat.com" , "bagasdotme@gmail.com" , "ak@linux.intel.com" , "Wysocki, Rafael J" , "kirill.shutemov@linux.intel.com" , "Chatre, Reinette" , "Christopherson,, Sean" , "pbonzini@redhat.com" , "tglx@linutronix.de" , "Yamahata, Isaku" , "linux-mm@kvack.org" , "peterz@infradead.org" , "Shahar, Sagi" , "imammedo@redhat.com" , "Gao, Chao" , "Brown, Len" , "sathyanarayanan.kuppuswamy@linux.intel.com" , "Huang, Ying" , "Williams, Dan J" References: <9b3582c9f3a81ae68b32d9997fcd20baecb63b9b.1685887183.git.kai.huang@intel.com> <1e58e3df-ae9a-607c-cfc3-4f3d033ed531@intel.com> From: Dave Hansen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 8CA0B14000B X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: ys4gb3ayx5nn1syin9igx3snxea9mbox X-HE-Tag: 1686184199-814337 X-HE-Meta: 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 Tj3cjl7U nyUSTVVu6Ci54FHKqQmJEkJZP2mHEgOvXF5tPXVvKk+cb1zDu3Ys/3VnRhbg9l347TjifZKy7XI1ii5puwpg1MwcpZjswbumIoIyb/3AB5p5SdRz1xMnjwP9uovAO9m93LTZeSNQN4pnoFofyqSShEDHz4ehGjdNSXdnlrqqh0paE0zDtcez75WcjOyfZMPZY7dY7 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 6/7/23 16:36, Huang, Kai wrote: > On Wed, 2023-06-07 at 08:08 -0700, Hansen, Dave wrote: >> On 6/4/23 07:27, Kai Huang wrote: >>> Certain SEAMCALL leaf functions may return error due to running out of >>> entropy, in which case the SEAMCALL should be retried as suggested by >>> the TDX spec. >>> >>> Handle this case in SEAMCALL common function. Mimic the existing >>> rdrand_long() to retry RDRAND_RETRY_LOOPS times. >> >> ... because who are we kidding? When the TDX module says it doesn't >> have enough entropy it means rdrand. > > The TDX spec says "e.g., RDRAND or RDSEED". Let's just say something a bit more useful and ambiguous: Some SEAMCALLs use the RDRAND hardware and can fail for the same reasons as RDRAND. Use the kernel RDRAND retry logic for them. We don't need to say "RDRAND and RDSEED", just saying "RDRAND hardware" is fine. Everybody knows what you mean.