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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 67D32C31E5C for ; Mon, 17 Jun 2019 15:54:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F0E7208C4 for ; Mon, 17 Jun 2019 15:54:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560786893; bh=aQEphLJjoGNsTWF7PUdVBXP9/NtJHbD77gDyFsJX9OY=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=GZJxubBe+nvmnpICjYWcHx3+Ziqw0nURq9+Q0Q/2eEHqCQkxbsgnfgGF0tscpwDuD ncEUJAjld05A1rOwz5DNq77sgbwOqQe7hlU9AUMY58kRiuZHvkRmO1j4FPWG0MgpmQ aHpBA7MVuplHdYAnKI9ylO0T+lj4pgY15rXnkOdA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728549AbfFQPyv (ORCPT ); Mon, 17 Jun 2019 11:54:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:37708 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728519AbfFQPyu (ORCPT ); Mon, 17 Jun 2019 11:54:50 -0400 Received: from mail-wr1-f50.google.com (mail-wr1-f50.google.com [209.85.221.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E75932166E for ; Mon, 17 Jun 2019 15:54:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560786890; bh=aQEphLJjoGNsTWF7PUdVBXP9/NtJHbD77gDyFsJX9OY=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=qhOUahTGEyUHegfv4CFWy7tkV4dfGHY5ttlEqkwBP2tiXzGEfMzJPElZH2oeSSJA0 rsnYLYI8jLtjfOKiK5Ee2GKss2TnarwRGAOSUPGb+qZpd65W4APU5Itf6Ar+aac5xH gguaXWWoFgjuokF/kcsWPV63ALSIUKuQ4QvaRPnU= Received: by mail-wr1-f50.google.com with SMTP id d18so10559945wrs.5 for ; Mon, 17 Jun 2019 08:54:49 -0700 (PDT) X-Gm-Message-State: APjAAAWfZuN+U9JO6lqigHzzD2E+lK5jMVxF5ojdeVNXxAgUnJvw8z3n qem0+sFJijAYaRS7OJxCev2mze+FHi/y4HIgurdedw== X-Google-Smtp-Source: APXvYqykHUxihfkEY2tiikg8dXKgA4M9BplCJytE01KiNZl2hAMC6m+RW666K7HHMIykrPzo3dGyP3UaxzXnfm7HuLw= X-Received: by 2002:a5d:6207:: with SMTP id y7mr55951191wru.265.1560786888514; Mon, 17 Jun 2019 08:54:48 -0700 (PDT) MIME-Version: 1.0 References: <20190612170834.14855-1-mhillenb@amazon.de> <58788f05-04c3-e71c-12c3-0123be55012c@amazon.com> <63b1b249-6bc7-ffd9-99db-d36dd3f1a962@intel.com> In-Reply-To: <63b1b249-6bc7-ffd9-99db-d36dd3f1a962@intel.com> From: Andy Lutomirski Date: Mon, 17 Jun 2019 08:54:36 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC 00/10] Process-local memory allocations for hiding KVM secrets To: Dave Hansen Cc: Alexander Graf , Thomas Gleixner , Marius Hillenbrand , kvm list , LKML , Kernel Hardening , Linux-MM , Alexander Graf , David Woodhouse , "the arch/x86 maintainers" , Andy Lutomirski , Peter Zijlstra Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 17, 2019 at 8:50 AM Dave Hansen wrote: > > On 6/17/19 12:38 AM, Alexander Graf wrote: > >> Yes I know, but as a benefit we could get rid of all the GSBASE > >> horrors in > >> the entry code as we could just put the percpu space into the local PGD. > > > > Would that mean that with Meltdown affected CPUs we open speculation > > attacks against the mmlocal memory from KVM user space? > > Not necessarily. There would likely be a _set_ of local PGDs. We could > still have pair of PTI PGDs just like we do know, they'd just be a local > PGD pair. > Unfortunately, this would mean that we need to sync twice as many top-level entries when we context switch.