On Tue, Jul 12, 2011 at 06:43:42PM +0200, Olaf Hering wrote:
>
> Migration of pv guests fails, the guest crashes on the target host once the
> guest is unpaused after transit. It happens when the guest is started on a
> small systen, then migrated from that small system to a large system.
> If the guest is started on a large system, then migrated to a small system and
> back to the large system, the migration will be successful.
>
> The issue is that mfn_to_pfn() makes use of machine_to_phys_order, which
> is only configured once early in the boot process. After migration to a
> large host the mfns will exceed the order from the small system and a
> wrong code path is taken.
>
> Calling xen_setup_machphys_mapping() again in the resume path will avoid
> the crash.
Oh, duh!
Let me queue that up for 3.0-rc7 unless there are objections?
>
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
>
> ---
> arch/x86/xen/mmu.c | 2 +-
> arch/x86/xen/suspend.c | 2 ++
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> Index: linux-3.0-rc7/arch/x86/xen/mmu.c
> ===================================================================
> --- linux-3.0-rc7.orig/arch/x86/xen/mmu.c
> +++ linux-3.0-rc7/arch/x86/xen/mmu.c
> @@ -1623,7 +1623,7 @@ static void __init xen_map_identity_earl
> set_page_prot(pmd, PAGE_KERNEL_RO);
> }
>
> -void __init xen_setup_machphys_mapping(void)
> +void xen_setup_machphys_mapping(void)
> {
> struct xen_machphys_mapping mapping;
> unsigned long machine_to_phys_nr_ents;
> Index: linux-3.0-rc7/arch/x86/xen/suspend.c
> ===================================================================
> --- linux-3.0-rc7.orig/arch/x86/xen/suspend.c
> +++ linux-3.0-rc7/arch/x86/xen/suspend.c
> @@ -43,6 +43,8 @@ void xen_arch_hvm_post_suspend(int suspe
>
> void xen_arch_post_suspend(int suspend_cancelled)
> {
> + xen_setup_machphys_mapping();
> +
> xen_build_mfn_list_list();
>
> xen_setup_shared_info();
>
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