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[198.145.29.99]) by mx.google.com with ESMTPS id j63si621083pgc.185.2019.06.17.08.54.50 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 17 Jun 2019 08:54:50 -0700 (PDT) Received-SPF: pass (google.com: domain of luto@kernel.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=qhOUahTG; spf=pass (google.com: domain of luto@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=luto@kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from mail-wr1-f47.google.com (mail-wr1-f47.google.com [209.85.221.47]) (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 0437821873 for ; Mon, 17 Jun 2019 15:54:50 +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-f47.google.com with SMTP id n4so2465443wrs.3 for ; Mon, 17 Jun 2019 08:54:49 -0700 (PDT) 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" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000015, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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.