From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1425571AbcBRLGp (ORCPT ); Thu, 18 Feb 2016 06:06:45 -0500 Received: from foss.arm.com ([217.140.101.70]:38230 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1425490AbcBRLG0 (ORCPT ); Thu, 18 Feb 2016 06:06:26 -0500 Date: Thu, 18 Feb 2016 11:06:16 +0000 From: Marc Zyngier To: Eric Auger Cc: eric.auger@st.com, alex.williamson@redhat.com, will.deacon@arm.com, joro@8bytes.org, tglx@linutronix.de, jason@lakedaemon.net, christoffer.dall@linaro.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, suravee.suthikulpanit@amd.com, patches@linaro.org, linux-kernel@vger.kernel.org, Manish.Jaggi@caviumnetworks.com, Bharat.Bhushan@freescale.com, pranav.sawargaonkar@gmail.com, p.fedin@samsung.com, iommu@lists.linux-foundation.org, sherry.hurwitz@amd.com, brijesh.singh@amd.com, leo.duran@amd.com, Thomas.Lendacky@amd.com Subject: Re: [RFC v3 07/15] iommu: iommu_get/put_single_reserved Message-ID: <20160218110616.05108071@arm.com> In-Reply-To: <1455264797-2334-8-git-send-email-eric.auger@linaro.org> References: <1455264797-2334-1-git-send-email-eric.auger@linaro.org> <1455264797-2334-8-git-send-email-eric.auger@linaro.org> Organization: ARM Ltd X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 12 Feb 2016 08:13:09 +0000 Eric Auger wrote: > This patch introduces iommu_get/put_single_reserved. > > iommu_get_single_reserved allows to allocate a new reserved iova page > and map it onto the physical page that contains a given physical address. > It returns the iova that is mapped onto the provided physical address. > Hence the physical address passed in argument does not need to be aligned. > > In case a mapping already exists between both pages, the IOVA mapped > to the PA is directly returned. > > Each time an iova is successfully returned a binding ref count is > incremented. > > iommu_put_single_reserved decrements the ref count and when this latter > is null, the mapping is destroyed and the iova is released. I wonder if there is a requirement for the caller to find out about the size of the mapping, or to impose a given size... MSIs clearly do not have that requirement (this is always a 32bit value), but since allocations usually pair address and size, I though I'd ask... Thanks, M. -- Jazz is not dead. It just smells funny.