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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] guest crash in wrmsr_hypervisor_regs if hypercall page is paged out
>>> On 02.05.13 at 16:43, Olaf Hering <olaf@xxxxxxxxx> wrote: > On Thu, May 02, Tim Deegan wrote: > >> At 20:19 +0200 on 30 Apr (1367353157), Olaf Hering wrote: >> > >> > With current xen-unstable I see this guest crash if the gfn 169ff is >> > paged out. The xenpaging -v output shows that 169ff is populated, but >> > appearently wrmsr_hypervisor_regs does not like the resulting mfn?! >> >> Looks that way: >> >> > (XEN) HVM10: Allocated Xen hypercall page at 169ff000 >> > (XEN) traps.c:654:d10 Bad GMFN 169ff (MFN 3e900000000) to MSR 40000000 >> >> That MFN looks like garbage, so I'm guessing that 'page' was null, i.e. >> get_page_from_gfn() returned NULL. I guess you'll need to instrument it >> up to figure out why. At least the GFN is a predictable constant which >> should make it easier to add debugging printout for just this case. > > The GMFN has p2m_t p2m_ram_paged, so the mfn is -1. > > Its not clear to me, how should wrmsr_hypervisor_regs handle a paged > gfn? I was under the impression that get_page_from_gfn would wait until > the gfn is paged-in again. We can't put a vCPU to sleep at arbitrary points yet, which means that right now the caller of the function is responsible for the wait-and-retry - normally that would be in hypercall handlers, but obviously you need this here too. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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