From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [RFC PATCH 2/3] arch, arm32: add the XEN_DOMCTL_memory_mapping hypercall Date: Fri, 07 Mar 2014 11:41:50 +0800 Message-ID: <53193FFE.9080605@linaro.org> References: <1393721365-22458-1-git-send-email-avanzini.arianna@gmail.com> <1393721365-22458-3-git-send-email-avanzini.arianna@gmail.com> <531543BE.4080301@linaro.org> <53191948.4090100@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <53191948.4090100@gmail.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Arianna Avanzini , Eric Trudeau , "xen-devel@lists.xen.org" Cc: "julien.grall@citrix.com" , "dario.faggioli@citrix.com" , "paolo.valente@unimore.it" , "viktor.kleinik@globallogic.com" , "stefano.stabellini@eu.citrix.com" List-Id: xen-devel@lists.xenproject.org Hello Arianna, On 07/03/14 08:56, Arianna Avanzini wrote: >>> Beware: I found that map_mmio_regions was off by one page unless I changed >>> "gfn + nr_mfns - 1" to "gfn + nr_mfns". >>> This may have been fixed in more recent upstream code. >> >> That makes me think, map_mmio_regions is buggy if the range is not correctly >> aligned. For instance: >> >> start_gaddr = 0x1001 and end_gaddr = 0x2001, we only map 0x1000-0x2000 to the >> domain. >> >> The problem is the same with p2m_populate_ram (even if I doubt that RAM range is >> not page-aligned). >> >> I see 2 solutions to fix it: >> - Change map_mmio_regions prototype to use frame is instead address. >> - Aligned the input addresses. >> >> IHMO, the former seems to be better, at least it avoid developer to discover >> that some bits was mapped under his feet. >> > > Sorry if I intrude here, thank you for pointing that out. As of now I have tried > to simply pass aligned addresses to map_mmio_regions() when it is invoked by the > memory_mapping hypercall. FYI, the end address should be PAGE-aligned minus 1. Otherwise you will map a spurious page to the guest. > Sorry for the additional question, do you think that it would be appropriate to > add to the series a patch implementing one of the above-described solutions (the > one believed to be better)? I'd like to have some input from Ian before. I think for now it's fine to stay with the current implementation. Regards, -- Julien Grall