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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 F2DC8C4338F for ; Tue, 24 Aug 2021 18:55:53 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A4D6D613A7 for ; Tue, 24 Aug 2021 18:55:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org A4D6D613A7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 7654C817BD; Tue, 24 Aug 2021 18:55:53 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Y-57UgRP4UaH; Tue, 24 Aug 2021 18:55:50 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp1.osuosl.org (Postfix) with ESMTPS id 86FEF80EE8; Tue, 24 Aug 2021 18:55:49 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6D648C001A; Tue, 24 Aug 2021 18:55:49 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 10463C000E for ; Tue, 24 Aug 2021 18:55:48 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id CF1C24078F for ; Tue, 24 Aug 2021 18:55:44 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp4.osuosl.org (amavisd-new); dkim=pass (2048-bit key) header.d=kernel.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 5iZsoGLTy1-c for ; Tue, 24 Aug 2021 18:55:43 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp4.osuosl.org (Postfix) with ESMTPS id B02F94076B for ; Tue, 24 Aug 2021 18:55:43 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id DC45C61178; Tue, 24 Aug 2021 18:55:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629831343; bh=d/Fr0mBMXraTW+Ew01Yil+DCXSSjTvd5q9qem138RPE=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=t5cnqJZj36He9/zjegb9+V9+U3YiQamVwwKvzU1WrQq1Qaa+otNQjIpOiBqlsMEdM /Hqh3iR5wCXL+mGe6LqhWoGFpktgZ9b12IewTtcxFDv1maXi/yfljyIhDOnl/z5XMt kqtFzOpSSbjXME95XQ70DtnBwGzFO7+zGwLjQy9HFrGMtxqHJNh2QDgWLglZ5C35GH hnCcNOL4lw0MsGxbMWF0J/SLHbKZSnrBA1q8ych11j+zeKHwRGuUnfE1N3/f5XMPXs oyQMr/mk68NjLI3llarex6W2QR/Y9G8ODdkhohBntXV7QiObuNljxc6qSrgPHYc8ep rrO89m1YOIQlQ== Date: Tue, 24 Aug 2021 13:55:41 -0500 From: Bjorn Helgaas To: Andi Kleen Subject: Re: [PATCH v4 11/15] pci: Add pci_iomap_shared{,_range} Message-ID: <20210824185541.GA3485816@bjorn-Precision-5520> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Cc: "Kuppuswamy, Sathyanarayanan" , Kuppuswamy Sathyanarayanan , "Michael S. Tsirkin" , Peter Zijlstra , Linux PCI , linux-mips@vger.kernel.org, James E J Bottomley , Dave Hansen , Peter H Anvin , sparclinux@vger.kernel.org, Rajat Jain , Thomas Gleixner , linux-arch , Jonathan Corbet , Helge Deller , X86 ML , Ingo Molnar , Arnd Bergmann , Tony Luck , Borislav Petkov , Andy Lutomirski , Bjorn Helgaas , Dan Williams , virtualization@lists.linux-foundation.org, Richard Henderson , Thomas Bogendoerfer , linux-parisc@vger.kernel.org, Sean Christopherson , Linux Doc Mailing List , Linux Kernel Mailing List , linux-alpha@vger.kernel.org, "David S . Miller" , Kirill Shutemov X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" [+cc Rajat; I still don't know what "shared memory with a hypervisor in a confidential guest" means, but now we're talking about hardened drivers and allow lists, which Rajat is interested in] On Tue, Aug 24, 2021 at 10:20:44AM -0700, Andi Kleen wrote: > > > I see. Hmm. It's a bit of a random thing to do it at the map time > > though. E.g. DMA is all handled transparently behind the DMA API. > > Hardening is much more than just replacing map with map_shared > > and I suspect what you will end up with is basically > > vendors replacing map with map shared to make things work > > for their users and washing their hands. > > That concept exists too. There is a separate allow list for the drivers. So > just adding shared to a driver is not enough, until it's also added to the > allowlist > > Users can of course chose to disable the allowlist, but they need to > understand the security implications. > > > I would say an explicit flag in the driver that says "hardened" > > and refusing to init a non hardened one would be better. > > We have that too (that's the device filtering) > > But the problem is that device filtering just stops the probe functions, not > the initcalls, and lot of legacy drivers do MMIO interactions before going > into probe. In some cases it's unavoidable because of the device doesn't > have a separate enumeration mechanism it needs some kind of probing to even > check for its existence And since we don't want to change all of them it's > far safer to make the ioremap opt-in. > > > -Andi > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization