[Xen-devel] Re: Bug#599089: linux-image-2.6.32-5-xen-686: Kernel Panics when using NFS from DomU to Dom0

[Ian Campbell <ijc@xxxxxxxxxxxxxx>]

On Tue, 2010-10-05 at 09:54 -0700, Jeremy Fitzhardinge wrote: 
> On 10/05/2010 02:52 AM, Ian Campbell wrote:
> > On Tue, 2010-10-05 at 10:47 +0100, Ian Campbell wrote:
> >> In addition to the kernel logging of the error I get this from the
> >> hypervisor:
> >> (XEN) mm.c:2062:d0 Error pfn 16d99: rd=ffff83011fefa000,
> >> od=0000000000000000, caf=180000000000000, taf=0000000000000000
> >> (XEN) mm.c:658:d0 Could not get page ref for pfn 16d99
> >> (XEN) mm.c:3621:d0 Could not get page for mach->phys update
> > Adding a bit more logging to the kernel I get:
> > gnttb_copy_grant_page old c22ebcd8 P:0x1ec8e M:0xc499d F:0x41000000
> > gnttb_copy_grant_page new c2324ce0 P:0x1fe18 M:0x11cd32 F:0x40000000
> > (XEN) mm.c:2062:d0 Error pfn 1cd32: rd=ffff83011fefa000, 
> > od=0000000000000000, caf=180000000000000, taf=0000000000000000
> > (XEN) mm.c:658:d0 Could not get page ref for pfn 1cd32
> > (XEN) mm.c:3621:d0 Could not get page for mach->phys update
> >
> > Notice how MFN 0x11cd32 has become 0x1cd32 by the time it gets to the
> > hypervisor!
> 
> Oy, more of these.  It might be better to use PFN_PHYS().

I thought there ought to be a helper but couldn't find one, PFN_PHYS
sounds like a good bet, unless we want to alias it as MFN_MACH or
something?


> J
> 
> > The following fixes it for me.
> >
> > From: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Subject: xen: grant table: do not truncate machine address on 
> > gnttab_copy_grant_page
> >
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> >
> > --- a/drivers/xen/grant-table.c
> > +++ b/drivers/xen/grant-table.c
> > @@ -578,7 +578,7 @@ int gnttab_copy_grant_page(grant_ref_t ref, struct page 
> > **pagep)
> >     if (!xen_feature(XENFEAT_auto_translated_physmap)) {
> >             set_phys_to_machine(page_to_pfn(new_page), INVALID_P2M_ENTRY);
> >  
> > -           mmu.ptr = (new_mfn << PAGE_SHIFT) | MMU_MACHPHYS_UPDATE;
> > +           mmu.ptr = ((u64)new_mfn << PAGE_SHIFT) | MMU_MACHPHYS_UPDATE;
> >             mmu.val = pfn;
> >             err = HYPERVISOR_mmu_update(&mmu, 1, NULL, DOMID_SELF);
> >             BUG_ON(err);
> >
> 
> 

-- 
Ian Campbell

"Not Hercules could have knock'd out his brains, for he had none."
                -- Shakespeare

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