Merge tag 'stable/for-linus-3.8-rc7-tag-two' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen

Pull xen fixes from Konrad Rzeszutek Wilk:
 "Two fixes:

   - A simple bug-fix for redundant NULL check.

   - CVE-2013-0228/XSA-42: x86/xen: don't assume %ds is usable in
     xen_iret for 32-bit PVOPS

  and two reverts:

   - Revert the PVonHVM kexec.  The patch introduces a regression with
     older hypervisor stacks, such as Xen 4.1."

* tag 'stable/for-linus-3.8-rc7-tag-two' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
  Revert "xen PVonHVM: use E820_Reserved area for shared_info"
  Revert "xen/PVonHVM: fix compile warning in init_hvm_pv_info"
  xen: remove redundant NULL check before unregister_and_remove_pcpu().
  x86/xen: don't assume %ds is usable in xen_iret for 32-bit PVOPS.

4 files changed, 32 insertions, 63 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 138e5667409a..e0140923062f 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1517,72 +1517,51 @@ asmlinkage void __init xen_start_kernel(void)
 #endif
 }
 
-#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;
-
-static void xen_hvm_connect_shared_info(unsigned long pfn)
+void __ref xen_hvm_init_shared_info(void)
 {
+	int cpu;
 	struct xen_add_to_physmap xatp;
+	static struct shared_info *shared_info_page = 0;
 
+	if (!shared_info_page)
+		shared_info_page = (struct shared_info *)
+			extend_brk(PAGE_SIZE, PAGE_SIZE);
 	xatp.domid = DOMID_SELF;
 	xatp.idx = 0;
 	xatp.space = XENMAPSPACE_shared_info;
-	xatp.gpfn = pfn;
+	xatp.gpfn = __pa(shared_info_page) >> PAGE_SHIFT;
 	if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
 		BUG();
 
-}
-static void __init xen_hvm_set_shared_info(struct shared_info *sip)
-{
-	int cpu;
-
-	HYPERVISOR_shared_info = sip;
+	HYPERVISOR_shared_info = (struct shared_info *)shared_info_page;
 
 	/* 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. */
-	for_each_online_cpu(cpu)
+	 * 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) {
 		per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
-}
-
-/* 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);
 }
 
+#ifdef CONFIG_XEN_PVHVM
 static void __init init_hvm_pv_info(void)
 {
-	uint32_t ecx, edx, pages, msr, base;
+	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);
@@ -1633,22 +1612,12 @@ static void __init xen_hvm_guest_init(void)
 
 static bool __init xen_hvm_platform(void)
 {
-	uint32_t eax, ebx, ecx, edx, base;
-
 	if (xen_pv_domain())
 		return false;
 
-	base = xen_cpuid_base();
-	if (!base)
+	if (!xen_cpuid_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;
 }
 
diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index ae8a00c39de4..45329c8c226e 100644
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -30,7 +30,7 @@ void xen_arch_hvm_post_suspend(int suspend_cancelled)
 {
 #ifdef CONFIG_XEN_PVHVM
 	int cpu;
-	xen_hvm_resume_shared_info();
+	xen_hvm_init_shared_info();
 	xen_callback_vector();
 	xen_unplug_emulated_devices();
 	if (xen_feature(XENFEAT_hvm_safe_pvclock)) {
diff --git a/arch/x86/xen/xen-asm_32.S b/arch/x86/xen/xen-asm_32.S
index f9643fc50de5..33ca6e42a4ca 100644
--- a/arch/x86/xen/xen-asm_32.S
+++ b/arch/x86/xen/xen-asm_32.S
@@ -89,11 +89,11 @@ ENTRY(xen_iret)
 	 */
 #ifdef CONFIG_SMP
 	GET_THREAD_INFO(%eax)
-	movl TI_cpu(%eax), %eax
-	movl __per_cpu_offset(,%eax,4), %eax
-	mov xen_vcpu(%eax), %eax
+	movl %ss:TI_cpu(%eax), %eax
+	movl %ss:__per_cpu_offset(,%eax,4), %eax
+	mov %ss:xen_vcpu(%eax), %eax
 #else
-	movl xen_vcpu, %eax
+	movl %ss:xen_vcpu, %eax
 #endif
 
 	/* check IF state we're restoring */
@@ -106,11 +106,11 @@ ENTRY(xen_iret)
 	 * resuming the code, so we don't have to be worried about
 	 * being preempted to another CPU.
 	 */
-	setz XEN_vcpu_info_mask(%eax)
+	setz %ss:XEN_vcpu_info_mask(%eax)
 xen_iret_start_crit:
 
 	/* check for unmasked and pending */
-	cmpw $0x0001, XEN_vcpu_info_pending(%eax)
+	cmpw $0x0001, %ss:XEN_vcpu_info_pending(%eax)
 
 	/*
 	 * If there's something pending, mask events again so we can
@@ -118,7 +118,7 @@ xen_iret_start_crit:
 	 * touch XEN_vcpu_info_mask.
 	 */
 	jne 1f
-	movb $1, XEN_vcpu_info_mask(%eax)
+	movb $1, %ss:XEN_vcpu_info_mask(%eax)
 
 1:	popl %eax
 
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index d2e73d19d366..a95b41744ad0 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -40,7 +40,7 @@ void xen_enable_syscall(void);
 void xen_vcpu_restore(void);
 
 void xen_callback_vector(void);
-void xen_hvm_resume_shared_info(void);
+void xen_hvm_init_shared_info(void);
 void xen_unplug_emulated_devices(void);
 
 void __init xen_build_dynamic_phys_to_machine(void);