diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 586d838..a90c3bb 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1495,51 +1495,72 @@
 #endif
 }
 
-void __ref xen_hvm_init_shared_info(void)
-{
-	int cpu;
-	struct xen_add_to_physmap xatp;
-	static struct shared_info *shared_info_page = 0;
+#ifdef CONFIG_XEN_PVHVM
+#define HVM_SHARED_INFO_ADDR 0xFE700000UL
+static struct shared_info *xen_hvm_shared_info;
+static unsigned long xen_hvm_sip_phys;
+static int xen_major, xen_minor;
 
-	if (!shared_info_page)
-		shared_info_page = (struct shared_info *)
-			extend_brk(PAGE_SIZE, PAGE_SIZE);
+static void xen_hvm_connect_shared_info(unsigned long pfn)
+{
+	struct xen_add_to_physmap xatp;
+
 	xatp.domid = DOMID_SELF;
 	xatp.idx = 0;
 	xatp.space = XENMAPSPACE_shared_info;
-	xatp.gpfn = __pa(shared_info_page) >> PAGE_SHIFT;
+	xatp.gpfn = pfn;
 	if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
 		BUG();
 
-	HYPERVISOR_shared_info = (struct shared_info *)shared_info_page;
+}
+static void __init xen_hvm_set_shared_info(struct shared_info *sip)
+{
+	int cpu;
+
+	HYPERVISOR_shared_info = sip;
 
 	/* xen_vcpu is a pointer to the vcpu_info struct in the shared_info
 	 * page, we use it in the event channel upcall and in some pvclock
 	 * related functions. We don't need the vcpu_info placement
 	 * optimizations because we don't use any pv_mmu or pv_irq op on
-	 * HVM.
-	 * When xen_hvm_init_shared_info is run at boot time only vcpu 0 is
-	 * online but xen_hvm_init_shared_info is run at resume time too and
-	 * in that case multiple vcpus might be online. */
-	for_each_online_cpu(cpu) {
+	 * HVM. */
+	for_each_online_cpu(cpu)
 		per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
-	}
 }
 
-#ifdef CONFIG_XEN_PVHVM
+/* Reconnect the shared_info pfn to a (new) mfn */
+void xen_hvm_resume_shared_info(void)
+{
+	xen_hvm_connect_shared_info(xen_hvm_sip_phys >> PAGE_SHIFT);
+}
+
+/* Xen tools prior to Xen 4 do not provide a E820_Reserved area for guest usage.
+ * On these old tools the shared info page will be placed in E820_Ram.
+ * Xen 4 provides a E820_Reserved area at 0xFC000000, and this code expects
+ * that nothing is mapped up to HVM_SHARED_INFO_ADDR.
+ * Xen 4.3+ provides an explicit 1MB area at HVM_SHARED_INFO_ADDR which is used
+ * here for the shared info page. */
+static void __init xen_hvm_init_shared_info(void)
+{
+	if (xen_major < 4) {
+		xen_hvm_shared_info = extend_brk(PAGE_SIZE, PAGE_SIZE);
+		xen_hvm_sip_phys = __pa(xen_hvm_shared_info);
+	} else {
+		xen_hvm_sip_phys = HVM_SHARED_INFO_ADDR;
+		set_fixmap(FIX_PARAVIRT_BOOTMAP, xen_hvm_sip_phys);
+		xen_hvm_shared_info =
+		(struct shared_info *)fix_to_virt(FIX_PARAVIRT_BOOTMAP);
+	}
+	xen_hvm_connect_shared_info(xen_hvm_sip_phys >> PAGE_SHIFT);
+	xen_hvm_set_shared_info(xen_hvm_shared_info);
+}
+
 static void __init init_hvm_pv_info(void)
 {
-	int major, minor;
 	uint32_t eax, ebx, ecx, edx, pages, msr, base;
 	u64 pfn;
 
 	base = xen_cpuid_base();
-	cpuid(base + 1, &eax, &ebx, &ecx, &edx);
-
-	major = eax >> 16;
-	minor = eax & 0xffff;
-	printk(KERN_INFO "Xen version %d.%d.\n", major, minor);
-
 	cpuid(base + 2, &pages, &msr, &ecx, &edx);
 
 	pfn = __pa(hypercall_page);
@@ -1590,12 +1611,22 @@
 
 static bool __init xen_hvm_platform(void)
 {
+	uint32_t eax, ebx, ecx, edx, base;
+
 	if (xen_pv_domain())
 		return false;
 
-	if (!xen_cpuid_base())
+	base = xen_cpuid_base();
+	if (!base)
 		return false;
 
+	cpuid(base + 1, &eax, &ebx, &ecx, &edx);
+
+	xen_major = eax >> 16;
+	xen_minor = eax & 0xffff;
+
+	printk(KERN_INFO "Xen version %d.%d.\n", xen_major, xen_minor);
+
 	return true;
 }