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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 F1EDDC43331 for ; Thu, 5 Sep 2019 16:29:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 978FC2082E for ; Thu, 5 Sep 2019 16:29:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=shipmail.org header.i=@shipmail.org header.b="GLdXXnhL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733270AbfIEQ3h (ORCPT ); Thu, 5 Sep 2019 12:29:37 -0400 Received: from pio-pvt-msa3.bahnhof.se ([79.136.2.42]:43220 "EHLO pio-pvt-msa3.bahnhof.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730777AbfIEQ3g (ORCPT ); Thu, 5 Sep 2019 12:29:36 -0400 Received: from localhost (localhost [127.0.0.1]) by pio-pvt-msa3.bahnhof.se (Postfix) with ESMTP id 352D23FBBA; Thu, 5 Sep 2019 18:29:29 +0200 (CEST) Authentication-Results: pio-pvt-msa3.bahnhof.se; dkim=pass (1024-bit key; unprotected) header.d=shipmail.org header.i=@shipmail.org header.b=GLdXXnhL; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at bahnhof.se Received: from pio-pvt-msa3.bahnhof.se ([127.0.0.1]) by localhost (pio-pvt-msa3.bahnhof.se [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id GkcQmJL962Gx; Thu, 5 Sep 2019 18:29:28 +0200 (CEST) Received: from mail1.shipmail.org (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) (Authenticated sender: mb878879) by pio-pvt-msa3.bahnhof.se (Postfix) with ESMTPA id 99AC53FA34; Thu, 5 Sep 2019 18:29:26 +0200 (CEST) Received: from localhost.localdomain (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) by mail1.shipmail.org (Postfix) with ESMTPSA id 25A64360160; Thu, 5 Sep 2019 18:29:26 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=shipmail.org; s=mail; t=1567700966; bh=pG0TnA/QjvfGPWD0SGrgVkNWASVfS3us4YRoLbkZweY=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=GLdXXnhLdXo93d/AM7fRLLrTjXj3fu7aaTaeuCI4iZREMNJ+ZsgPjdeS+6AT+ixkt q/8CIqkJRBuS6OlPPSCqjgoZkgt4cCoaKZDdmjMMVfXUudhhI2HDTmuR+MtVxeJuXc lD1eDeynjNfo15bMPuyzhaC240h/m3KKT/sg0wcc= Subject: Re: [RFC PATCH 1/2] x86: Don't let pgprot_modify() change the page encryption bit To: Dave Hansen , linux-kernel@vger.kernel.org, x86@kernel.org, pv-drivers@vmware.com Cc: Thomas Hellstrom , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Christoph Hellwig , =?UTF-8?Q?Christian_K=c3=b6nig?= , Marek Szyprowski , Tom Lendacky , "Shutemov, Kirill" References: <20190905103541.4161-1-thomas_os@shipmail.org> <20190905103541.4161-2-thomas_os@shipmail.org> <608bbec6-448e-f9d5-b29a-1984225eb078@intel.com> <1badd275-91aa-45a6-0a89-ded65c7c3829@intel.com> From: =?UTF-8?Q?Thomas_Hellstr=c3=b6m_=28VMware=29?= Organization: VMware Inc. Message-ID: <1ceb9abc-7a11-eaa1-b286-11647211e2fc@shipmail.org> Date: Thu, 5 Sep 2019 18:29:25 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <1badd275-91aa-45a6-0a89-ded65c7c3829@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/5/19 5:59 PM, Dave Hansen wrote: > On 9/5/19 8:21 AM, Thomas Hellström (VMware) wrote: >>>>   #define pgprot_modify pgprot_modify >>>>   static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t >>>> newprot) >>>>   { >>>> -    pgprotval_t preservebits = pgprot_val(oldprot) & _PAGE_CHG_MASK; >>>> -    pgprotval_t addbits = pgprot_val(newprot); >>>> +    pgprotval_t preservebits = pgprot_val(oldprot) & >>>> +        (_PAGE_CHG_MASK | sme_me_mask); >>>> +    pgprotval_t addbits = pgprot_val(newprot) & ~sme_me_mask; >>>>       return __pgprot(preservebits | addbits); >>>>   } >>> _PAGE_CHG_MASK is claiming similar functionality about preserving bits >>> when changing PTEs: > ... >>>> #define _PAGE_CHG_MASK  (PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT >>>> |         \ >>>>                           _PAGE_SPECIAL | _PAGE_ACCESSED | >>>> _PAGE_DIRTY | \ >>>>                           _PAGE_SOFT_DIRTY | _PAGE_DEVMAP) >>> This makes me wonder if we should be including sme_me_mask in >>> _PAGE_CHG_MASK (logically). >> I was thinking the same. But what confuses me is that addbits isn't >> masked with ~_PAGE_CHG_MASK, which is needed for sme_me_mask, since the >> problem otherwise is typically that the encryption bit is incorrectly >> set in addbits. I wonder whether it's an optimization or intentional. > I think there's a built-in assumption that 'newprot' won't have any of > the _PAGE_CHG_MASK bits set. That makes sense because there are no > protection bits in the mask. But, the code certainly doesn't enforce that. > > Are you seeing 'sme_me_mask' bits set in 'newprot'? Yes. AFAIK it's only one bit, and typically always set. /Thomas