[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC PATCH 2/3] arch, arm32: add the XEN_DOMCTL_memory_mapping hypercall
On 03/07/2014 04:41 AM, Julien Grall wrote: > > 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. > Thank you for pointing that out. >> 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. > OK. Thank you for making this clear. > Regards, > -- /* * Arianna Avanzini * avanzini.arianna@xxxxxxxxx * 73628@xxxxxxxxxxxxxxxxxxx */ _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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