[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen/arm: Implement domain_get_maximum_gpfn
On Wed, 2014-07-02 at 10:19 +0100, Julien Grall wrote: > Hi Ian, > > On 02/07/14 10:12, Ian Campbell wrote: > > On Tue, 2014-07-01 at 15:57 +0100, Julien Grall wrote: > >> The function domain_get_maximum_gpfn is returning the maximum gpfn ever > >> mapped in the guest. We can use d->arch.p2m.max_mapped_gfn for this > >> purpose. > > > > What is using the result of this hypercall? > > The result is at least used by xc_dom_gnttab_hvm_seed, to get a scratch > GFN to initialize grant table. > > IHMO this is buggy on ARM (and x86?), because we could have map > everything up to the end of the address space (currently 40 bits). I wonder if we could find a way to not need this hypercall at all. Any reason why both arm and x86 can't just use a fixed scratch pfn for this temporary mapping? Both of them surely have spaces which they can guarantee won't overlap with anything. > I plan to rework a bit this code. > > Without this patch, xc_dom_gnttab_hvm_seed will use by mistake the pfn 0 > (0xffffffff + 1). > > Regards, > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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