[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH RFC] libxl: set 1GB MMIO hole for PVH
On Wed, May 09, 2018 at 06:12:28PM +0200, Juergen Gross wrote: > On 09/05/18 18:07, Roger Pau Monne wrote: > > This prevents page-shattering, by being able to populate the RAM > > regions below 4GB using 1GB pages, provided the guest memory size is > > set to a multiple of a GB. > > > > Note that there are some special and ACPI pages in the MMIO hole that > > will be populated using smaller order pages, but those shouldn't be > > accessed as often as RAM regions. > > Would it be possible somehow to put a potential firmware into that > 1GB region, too, if it needs any memory in high memory? Seabios e.g. > is taking the last RAM page of the guest for its hypercall page, which > will again shatter GB mappings. I know this comment is related to HVM guests, but I'm not sure I see how setting the hypercall page shatters GB mappings. Setting the hypercall page doesn't involve changing any p2m mappings, but just filling a guest RAM page with some data. Roger. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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