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 9CD7DC4727D for ; Tue, 22 Sep 2020 18:02:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B06C22388B for ; Tue, 22 Sep 2020 18:02:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="UgM9Rpk2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B06C22388B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=alien8.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4EBB46B0037; Tue, 22 Sep 2020 14:02:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 476C58E0001; Tue, 22 Sep 2020 14:02:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 33CEB6B005A; Tue, 22 Sep 2020 14:02:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0246.hostedemail.com [216.40.44.246]) by kanga.kvack.org (Postfix) with ESMTP id 17BDB6B0037 for ; Tue, 22 Sep 2020 14:02:19 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id B5D433634 for ; Tue, 22 Sep 2020 18:02:18 +0000 (UTC) X-FDA: 77291466756.11.part59_4b176142714f Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin11.hostedemail.com (Postfix) with ESMTP id 943CF180F8B82 for ; Tue, 22 Sep 2020 18:02:18 +0000 (UTC) X-HE-Tag: part59_4b176142714f X-Filterd-Recvd-Size: 3762 Received: from mail.skyhub.de (mail.skyhub.de [5.9.137.197]) by imf08.hostedemail.com (Postfix) with ESMTP for ; Tue, 22 Sep 2020 18:02:17 +0000 (UTC) Received: from zn.tnic (p200300ec2f0bfb00105f6dfc0f2f9e65.dip0.t-ipconnect.de [IPv6:2003:ec:2f0b:fb00:105f:6dfc:f2f:9e65]) (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 C0E051EC027B; Tue, 22 Sep 2020 20:02:15 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1600797735; 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=9wsNfmarJ+ZwBMwKOM+TIGDi/giemsqRt1pXRwMjD/8=; b=UgM9Rpk2W4r30U2yLEgZ1N7PL8I3ft8uk2H/04npg38QSFeWxbPJUz6CfcFF9pB5ieaL2s NmnNGLh0M4uC9Rso5gHnoS37S13/RcJEmFF3rseBErfi9QlowUApB386aZZcpJYR/r15Ii qDwNj5pRJRzLAUH08TsmAfeSFxQISdA= Date: Tue, 22 Sep 2020 20:02:03 +0200 From: Borislav Petkov To: Sean Christopherson Cc: Jarkko Sakkinen , x86@kernel.org, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Jethro Beekman , Jordan Hand , Nathaniel McCallum , Chunyang Hui , Seth Moore , 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 16/24] x86/sgx: Add a page reclaimer Message-ID: <20200922180203.GQ22660@zn.tnic> References: <20200915112842.897265-1-jarkko.sakkinen@linux.intel.com> <20200915112842.897265-17-jarkko.sakkinen@linux.intel.com> <20200922104538.GE22660@zn.tnic> <20200922162437.GA30827@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200922162437.GA30827@linux.intel.com> 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 Tue, Sep 22, 2020 at 09:24:38AM -0700, Sean Christopherson wrote: > The "else if" is correct. Version Array (VA) pages have 512 slots that hold > metadata for evicted EPC pages, i.e. swapping a page out of the EPC requires > a VA slot. For simplicity (LOL), I'll say. > the approach we are taking for initial support is to reserve a VA slot > when adding a page to the enclave[*]. In most cases, reserving a slot > does not require allocating a new VA page, e.g. to reserve slots 1-511 > of the "current" VA page. The if-elif is handling the case where the > current VA page is fully reserved and a new one needs to be allocated. > The if handles the error, the elif handles success, i.e. > > if (IS_ERR(va_page)) <- needed a new VA page, allocation failed > return PTR_ERR(va_page); > else if (va_page) <- needed a new VA page, allocation succeeded > list_add(&va_page->list, &encl->va_pages); > else > <- reused the current VA page Aha, in that case va_page will be NULL but you're not using it in that function later and that current VA page is on encl->va_pages which others can get from there. Ok, gotcha. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette