[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] VMX virtual-apic: Update the p2m mapping alongside the control bit
At 10:46 +0100 on 26 May (1274870761), Keir Fraser wrote: > On 26/05/2010 09:57, "Tim Deegan" <Tim.Deegan@xxxxxxxxxxxxx> wrote: > > >> The dummy data page should not be migrated because it has p2m type > >> mmio_direct, which will fail the p2m_is_ram() check in mod_l1_entry() when > >> dom0 attempts to map the page to save/migrate it. > > > > Ah, so it will; I hadn't seen that. The full failure mode is actually > > on migrating from Xen 3.3 (where mod_l1_entry() didn't have that check) > > to a newer Xen on a machine where the HW APIC virt isn't supported. The > > sender sends the contents of the dummy page (incorrectly) and the > > receiver doesn't do anything (assuming that there'll be a hole in the > > p2m where the APIC should be). > > Well, even so, the patch would still appear to only clear the p2m entry if > the APIC is disabled or relocated. Why would either be the case during > save/migrate? Eh, good point. But it also re-sets the mmio-dm p2m entry in the case where the HW support _is_ available, which, now that I think of it, would also be broken. :) > Anyway, somewhat academic given we agree it's not needed at all in 3.4+ Well, forward compatibility for save files would be nice (and indeed is needed in XenServer for live upgrade of a server pool to a new version) but since 3.4 -> 4.0 works, I'm happy to let it go. Cheers, Tim. -- Tim Deegan <Tim.Deegan@xxxxxxxxxx> Principal Software Engineer, XenServer Engineering Citrix Systems UK Ltd. (Company #02937203, SL9 0BG) _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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