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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D3DB9C433F5 for ; Tue, 1 Mar 2022 11:44:11 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4K7FlF39nzz3c2P for ; Tue, 1 Mar 2022 22:44:09 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4K7Fkk0705z2yph for ; Tue, 1 Mar 2022 22:43:41 +1100 (AEDT) Received: by verein.lst.de (Postfix, from userid 2407) id 5C51F68AFE; Tue, 1 Mar 2022 12:43:35 +0100 (CET) Date: Tue, 1 Mar 2022 12:43:35 +0100 From: Christoph Hellwig To: Andrew Cooper Subject: Re: [PATCH 08/12] x86: centralize setting SWIOTLB_FORCE when guest memory encryption is enabled Message-ID: <20220301114335.GA2881@lst.de> References: <20220301105311.885699-1-hch@lst.de> <20220301105311.885699-9-hch@lst.de> <8e623a11-d809-4fab-401c-2ce609a9fc14@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <8e623a11-d809-4fab-401c-2ce609a9fc14@citrix.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "linux-hyperv@vger.kernel.org" , "x86@kernel.org" , "linux-ia64@vger.kernel.org" , "linux-pci@vger.kernel.org" , "linux-riscv@lists.infradead.org" , Christoph Hellwig , "linux-s390@vger.kernel.org" , Stefano Stabellini , Joerg Roedel , Konrad Rzeszutek Wilk , "tboot-devel@lists.sourceforge.net" , "xen-devel@lists.xenproject.org" , David Woodhouse , Tom Lendacky , Anshuman Khandual , Boris Ostrovsky , "linux-arm-kernel@lists.infradead.org" , Juergen Gross , "linuxppc-dev@lists.ozlabs.org" , "linux-mips@vger.kernel.org" , "iommu@lists.linux-foundation.org" , Robin Murphy , Lu Baolu Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Mar 01, 2022 at 11:39:29AM +0000, Andrew Cooper wrote: > This isn't really "must".  The guest is perfectly capable of sharing > memory with the hypervisor. > > It's just that for now, bounce buffering is allegedly faster, and the > simple way of getting it working. Yeah, I guess you щould just share/unshare on demand. But given that this isn't implemented it is a must in the current kernel. But if you want a different wording suggest one and I'll put it in.