xen: add p2m mfn_list_list

When saving a domain, the Xen tools need to remap all our mfns to
portable pfns.  In order to remap our p2m table, it needs to know
where all its pages are, so maintain the references to the p2m table
for it to use.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

3 files changed, 40 insertions, 3 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index d9faaa26c10..ce67dc8f36a 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -880,6 +880,8 @@ static __init void setup_shared_info(void)
 	/* In UP this is as good a place as any to set up shared info */
 	xen_setup_vcpu_info_placement();
 #endif
+
+	xen_setup_mfn_list_list();
 }
 
 static __init void xen_pagetable_setup_done(pgd_t *base)
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index da7b45b0506..4740cda3656 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -69,6 +69,13 @@ static unsigned long *p2m_top[TOP_ENTRIES]
 	__attribute__((section(".data.page_aligned"))) =
 		{ [ 0 ... TOP_ENTRIES - 1] = &p2m_missing[0] };
 
+/* Arrays of p2m arrays expressed in mfns used for save/restore */
+static unsigned long p2m_top_mfn[TOP_ENTRIES]
+	__attribute__((section(".bss.page_aligned")));
+
+static unsigned long p2m_top_mfn_list[TOP_ENTRIES / P2M_ENTRIES_PER_PAGE]
+	__attribute__((section(".bss.page_aligned")));
+
 static inline unsigned p2m_top_index(unsigned long pfn)
 {
 	BUG_ON(pfn >= MAX_DOMAIN_PAGES);
@@ -80,11 +87,35 @@ static inline unsigned p2m_index(unsigned long pfn)
 	return pfn % P2M_ENTRIES_PER_PAGE;
 }
 
+/* Build the parallel p2m_top_mfn structures */
+void xen_setup_mfn_list_list(void)
+{
+	unsigned pfn, idx;
+
+	for(pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_ENTRIES_PER_PAGE) {
+		unsigned topidx = p2m_top_index(pfn);
+
+		p2m_top_mfn[topidx] = virt_to_mfn(p2m_top[topidx]);
+	}
+
+	for(idx = 0; idx < ARRAY_SIZE(p2m_top_mfn_list); idx++) {
+		unsigned topidx = idx * P2M_ENTRIES_PER_PAGE;
+		p2m_top_mfn_list[idx] = virt_to_mfn(&p2m_top_mfn[topidx]);
+	}
+
+	BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
+
+	HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
+		virt_to_mfn(p2m_top_mfn_list);
+	HYPERVISOR_shared_info->arch.max_pfn = xen_start_info->nr_pages;
+}
+
+/* Set up p2m_top to point to the domain-builder provided p2m pages */
 void __init xen_build_dynamic_phys_to_machine(void)
 {
-	unsigned pfn;
 	unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list;
 	unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages);
+	unsigned pfn;
 
 	for(pfn = 0; pfn < max_pfn; pfn += P2M_ENTRIES_PER_PAGE) {
 		unsigned topidx = p2m_top_index(pfn);
@@ -105,7 +136,7 @@ unsigned long get_phys_to_machine(unsigned long pfn)
 	return p2m_top[topidx][idx];
 }
 
-static void alloc_p2m(unsigned long **pp)
+static void alloc_p2m(unsigned long **pp, unsigned long *mfnp)
 {
 	unsigned long *p;
 	unsigned i;
@@ -118,6 +149,8 @@ static void alloc_p2m(unsigned long **pp)
 
 	if (cmpxchg(pp, p2m_missing, p) != p2m_missing)
 		free_page((unsigned long)p);
+	else
+		*mfnp = virt_to_mfn(p);
 }
 
 void set_phys_to_machine(unsigned long pfn, unsigned long mfn)
@@ -139,7 +172,7 @@ void set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 		/* no need to allocate a page to store an invalid entry */
 		if (mfn == INVALID_P2M_ENTRY)
 			return;
-		alloc_p2m(&p2m_top[topidx]);
+		alloc_p2m(&p2m_top[topidx], &p2m_top_mfn[topidx]);
 	}
 
 	idx = p2m_index(pfn);
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 826d6e4c3da..a1bc89a8f16 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -18,6 +18,8 @@ extern struct start_info *xen_start_info;
 extern struct shared_info xen_dummy_shared_info;
 extern struct shared_info *HYPERVISOR_shared_info;
 
+void xen_setup_mfn_list_list(void);
+
 char * __init xen_memory_setup(void);
 void __init xen_arch_setup(void);
 void __init xen_init_IRQ(void);