Merge tag 'for-linus-4.16-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen fixes from Juergen Gross:
 "Only five small fixes for issues when running under Xen"

* tag 'for-linus-4.16-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: Fix {set,clear}_foreign_p2m_mapping on autotranslating guests
  pvcalls-back: do not return error on inet_accept EAGAIN
  xen-netfront: Fix race between device setup and open
  xen/grant-table: Use put_page instead of free_page
  x86/xen: init %gs very early to avoid page faults with stack protector

arch/x86/xen/p2m.c

@@ -694,6 +694,9 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
 	int i, ret = 0;
 	pte_t *pte;
 
+	if (xen_feature(XENFEAT_auto_translated_physmap))
+		return 0;
+
 	if (kmap_ops) {
 		ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
 						kmap_ops, count);
@@ -736,6 +739,9 @@ int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
 {
 	int i, ret = 0;
 
+	if (xen_feature(XENFEAT_auto_translated_physmap))
+		return 0;
+
 	for (i = 0; i < count; i++) {
 		unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
 		unsigned long pfn = page_to_pfn(pages[i]);

arch/x86/xen/xen-head.S

@@ -9,7 +9,9 @@
 
 #include <asm/boot.h>
 #include <asm/asm.h>
+#include <asm/msr.h>
 #include <asm/page_types.h>
+#include <asm/percpu.h>
 #include <asm/unwind_hints.h>
 
 #include <xen/interface/elfnote.h>
@@ -35,6 +37,20 @@ ENTRY(startup_xen)
 	mov %_ASM_SI, xen_start_info
 	mov $init_thread_union+THREAD_SIZE, %_ASM_SP
 
+#ifdef CONFIG_X86_64
+	/* Set up %gs.
+	 *
+	 * The base of %gs always points to the bottom of the irqstack
+	 * union.  If the stack protector canary is enabled, it is
+	 * located at %gs:40.  Note that, on SMP, the boot cpu uses
+	 * init data section till per cpu areas are set up.
+	 */
+	movl	$MSR_GS_BASE,%ecx
+	movq	$INIT_PER_CPU_VAR(irq_stack_union),%rax
+	cdq
+	wrmsr
+#endif
+
 	jmp xen_start_kernel
 END(startup_xen)
 	__FINIT