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[Xen-devel] [PATCH] xen: correctly restore pfn_to_mfn_list_list after re

To: " Jeremy Fitzhardinge" <jeremy@xxxxxxxx>
Subject: [Xen-devel] [PATCH] xen: correctly restore pfn_to_mfn_list_list after resume
From: Ian Campbell <ian.campbell@xxxxxxxxxx>
Date: Sat, 21 Nov 2009 11:32:49 +0000
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Ian Campbell <ian.campbell@xxxxxxxxxx>
Delivery-date: Sat, 21 Nov 2009 03:33:42 -0800
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pvops kernels >= 2.6.30 can currently only be saved and restored once. The
second attempt to save results in:

    ERROR Internal error: Frame# in pfn-to-mfn frame list is not in pseudophys
    ERROR Internal error: entry 0: p2m_frame_list[0] is 0xf2c2c2c2, max 0x120000
    ERROR Internal error: Failed to map/save the p2m frame list

I finally narrowed it down to:

    commit cdaead6b4e657f960d6d6f9f380e7dfeedc6a09b
        Author: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
        Date:   Fri Feb 27 15:34:59 2009 -0800

            xen: split construction of p2m mfn tables from registration

            Build the p2m_mfn_list_list early with the rest of the p2m table, 
            register it later when the real shared_info structure is in place.

            Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>

The unforeseen side-effect of this change was to cause the mfn list list to not
be rebuilt on resume. Prior to this change it would have been rebuilt via
xen_post_suspend() -> xen_setup_shared_info() -> xen_setup_mfn_list_list().

Fix by explicitly calling xen_build_mfn_list_list() from xen_post_suspend().

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
 arch/x86/xen/mmu.c     |    2 +-
 arch/x86/xen/suspend.c |    2 ++
 arch/x86/xen/xen-ops.h |    1 +
 3 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 3bf7b1d..bf4cd6b 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -185,7 +185,7 @@ static inline unsigned p2m_index(unsigned long pfn)
 /* Build the parallel p2m_top_mfn structures */
-static void __init xen_build_mfn_list_list(void)
+void xen_build_mfn_list_list(void)
        unsigned pfn, idx;
diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index 95be7b4..6343a5d 100644
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -27,6 +27,8 @@ void xen_pre_suspend(void)
 void xen_post_suspend(int suspend_cancelled)
+       xen_build_mfn_list_list();
        if (suspend_cancelled) {
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 3252932..f9153a3 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -25,6 +25,7 @@ extern struct shared_info *HYPERVISOR_shared_info;
 void xen_setup_mfn_list_list(void);
 void xen_setup_shared_info(void);
+void xen_build_mfn_list_list(void);
 void xen_setup_machphys_mapping(void);
 pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn);
 void xen_ident_map_ISA(void);

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