From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2FA65C4727D for ; Tue, 22 Sep 2020 08:29:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A638C239E5 for ; Tue, 22 Sep 2020 08:29:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="qKHk11PS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726767AbgIVI3Z (ORCPT ); Tue, 22 Sep 2020 04:29:25 -0400 Received: from mail.skyhub.de ([5.9.137.197]:34792 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726488AbgIVI3Z (ORCPT ); Tue, 22 Sep 2020 04:29:25 -0400 Received: from zn.tnic (p200300ec2f0bfb00524dde00a85e5113.dip0.t-ipconnect.de [IPv6:2003:ec:2f0b:fb00:524d:de00:a85e:5113]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 964C61EC047E; Tue, 22 Sep 2020 10:29:23 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1600763363; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=my0BiTfuw78PRSxQkYalUvNGgbAS+8+tGotWiPO3720=; b=qKHk11PS4bsI8+fCWlD1orBMgH8FXAnqSal8BmRD2ycHTiQsgjAkQT/XaD4CRP8asQb4Iw Xxj6FBbXRHicVhjY94W12OQZY6bK8N5DfajU60ba6qtc8Mh63Td5RC1HtTmLNeB9r8n1Sj YHOgngTbhQHUbA4k+/R3gZgeDe/udLE= Date: Tue, 22 Sep 2020 10:29:18 +0200 From: Borislav Petkov To: Sean Christopherson Cc: Jarkko Sakkinen , x86@kernel.org, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, Jethro Beekman , Haitao Huang , Chunyang Hui , Jordan Hand , Nathaniel McCallum , Seth Moore , Darren Kenny , Suresh Siddha , akpm@linux-foundation.org, andriy.shevchenko@linux.intel.com, asapek@google.com, cedric.xing@intel.com, chenalexchen@google.com, conradparker@google.com, cyhanish@google.com, dave.hansen@intel.com, haitao.huang@intel.com, josh@joshtriplett.org, kai.huang@intel.com, kai.svahn@intel.com, kmoy@google.com, ludloff@google.com, luto@kernel.org, nhorman@redhat.com, puiterwijk@redhat.com, rientjes@google.com, tglx@linutronix.de, yaozhangx@google.com Subject: Re: [PATCH v38 14/24] x86/sgx: Add SGX_IOC_ENCLAVE_INIT Message-ID: <20200922082918.GC22660@zn.tnic> References: <20200915112842.897265-1-jarkko.sakkinen@linux.intel.com> <20200915112842.897265-15-jarkko.sakkinen@linux.intel.com> <20200921173514.GI5901@zn.tnic> <20200921181021.GA24481@linux.intel.com> <20200921182753.GK5901@zn.tnic> <20200921191658.GA24823@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200921191658.GA24823@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 21, 2020 at 12:17:00PM -0700, Sean Christopherson wrote: > That was effectively my original suggestion as well, check for a stale cache > and retry indefinitely. I capitulated because it did feel like I was being > overly paranoid. I'm obviously ok going the retry indefinitely route :-). > > https://lkml.kernel.org/r/20180904163546.GA5421@linux.intel.com Right, so if EINIT is so expensive, why does it matter how many cyccles WRMSR has? I.e., you don't really need to cache - you simply write the 4 MSRs and you're done. Simple. As to "indefinitely" - caller can increment a counter which counts how many times it returned SGX_INVALID_EINITTOKEN. I guess when it reaches some too high number which should not be reached during normal usage patterns, you can give up and issue a message to say that counter reached max retries or so but other than that, you should be ok. That thing is running interruptible in a loop anyway... Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette