[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Identifying pagetype in they hypervisor
Hi Mike, On Monday 25 August 2008 03:01:05 Mike Sun wrote: > Thanks Mark. That's what I think I'm looking for. > > I think I've managed to confuse myself a bit again (haven't touched > the modifications I made to the shadow code in a while) with the > gmfn/mfn naming in the shadow code. In _sh_propagate(..., > target_fmn,..) and _sh_mark_dirty(..., gmfn), I'm assuming that a real > machine frame number is passed to those functions, not a > pseudo-physical one... am I correct? The shadow code isn't something I'm familiar with, except conceptually. My understanding of the naming was that: mfn = real machine frame number gmfn = machine frame number as seen by the guest gpfn = pseudo-physical frame number as seen by the guest For HVM, we have gmfn == gpfn and mfn is translated to gmfn by shadow-related code For PV (assuming we're not doing shadow_translate) we have mfn == gmfn and gpfn is translated to gmfn == mfn by the guest itself Does that help at all? Cheers, Mark > Basically, I need to be sure that when the sh_page_fault_handler() > eventually calls _sh_propagate(), it passes the machine frame number > of the faulting page, not the HVM guest's perceived physical address > (gmfn/pseudo-physical). > > Thanks, > Mike > > On Sun, Aug 24, 2008 at 9:10 PM, Mark Williamson > > <mark.williamson@xxxxxxxxxxxx> wrote: > > I'm looking at the latest code but I would think the same code applies. > > > > Maybe you could try mfn_to_page() to get the struct page_info * and then > > poke about in that for the current type? In order to make this useful > > you'd probably have to do a get_page or similar to avoid races with other > > CPUs. > > > > Cheers, > > Mark > > > > On Monday 25 August 2008 01:47:19 Mike Sun wrote: > >> Hi -- > >> > >> I'm working off of a bit older branch, 3.1.0, but hopefully the > >> question is still relevant. > >> > >> In the suspend/restore code in 'tools/libxc/xc_domain_save.c', as part > >> of the saved record, a list of pfn_types are saved prior to the actual > >> pages themselves. These pfn_types are pfns with a type bits > >> associated with them that are accessed with the XEN_DOMCTL_PFINFO_XTAB > >> bitmask. > >> > >> I'm doing some copy-on-write work, and when I intercept writes in the > >> hypervisor, I need to copy both the actual page, and the type > >> associated with the page (so that it could later be properly written > >> out to the save record). I've modified the shadow page table code to > >> handle write faults associated with CoW and am able to get the mfn of > >> the faulting page and perform the copy; I cannot seem to find where > >> given the mfn, I can find the page type associated with it. Could > >> anybody help point me to the right place or direction? > >> > >> Much thanks, > >> Mike > >> > >> _______________________________________________ > >> Xen-devel mailing list > >> Xen-devel@xxxxxxxxxxxxxxxxxxx > >> http://lists.xensource.com/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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