Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fix from Peter Anvin:
 "A single fix to not invoke the espfix code on Xen PV, as it turns out
  to oops the guest when invoked after all.  This patch leaves some
  amount of dead code, in particular unnecessary initialization of the
  espfix stacks when they won't be used, but in the interest of keeping
  the patch minimal that cleanup can wait for the next cycle"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86_64/entry/xen: Do not invoke espfix64 on Xen

3 files changed, 11 insertions, 21 deletions

diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
index bba3cf88e624..0a8b519226b8 100644
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -129,7 +129,7 @@ static inline notrace unsigned long arch_local_irq_save(void)
 
 #define PARAVIRT_ADJUST_EXCEPTION_FRAME /*  */
 
-#define INTERRUPT_RETURN        iretq
+#define INTERRUPT_RETURN        jmp native_iret
 #define USERGS_SYSRET64                         \
         swapgs;                                 \
         sysretq;
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index b25ca969edd2..c844f0816ab8 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -830,27 +830,24 @@ restore_args:
         RESTORE_ARGS 1,8,1
 
 irq_return:
+        INTERRUPT_RETURN
+
+ENTRY(native_iret)
         /*
          * Are we returning to a stack segment from the LDT?  Note: in
          * 64-bit mode SS:RSP on the exception stack is always valid.
          */
 #ifdef CONFIG_X86_ESPFIX64
         testb $4,(SS-RIP)(%rsp)
-        jnz irq_return_ldt
+        jnz native_irq_return_ldt
 #endif
 
-irq_return_iret:
-        INTERRUPT_RETURN
-        _ASM_EXTABLE(irq_return_iret, bad_iret)
-
-#ifdef CONFIG_PARAVIRT
-ENTRY(native_iret)
+native_irq_return_iret:
         iretq
-        _ASM_EXTABLE(native_iret, bad_iret)
-#endif
+        _ASM_EXTABLE(native_irq_return_iret, bad_iret)
 
 #ifdef CONFIG_X86_ESPFIX64
-irq_return_ldt:
+native_irq_return_ldt:
         pushq_cfi %rax
         pushq_cfi %rdi
         SWAPGS
@@ -872,7 +869,7 @@ irq_return_ldt:
         SWAPGS
         movq %rax,%rsp
         popq_cfi %rax
-        jmp irq_return_iret
+        jmp native_irq_return_iret
 #endif
 
         .section .fixup,"ax"
@@ -956,13 +953,8 @@ __do_double_fault:
         cmpl $__KERNEL_CS,CS(%rdi)
         jne do_double_fault
         movq RIP(%rdi),%rax
-        cmpq $irq_return_iret,%rax
-#ifdef CONFIG_PARAVIRT
-        je 1f
-        cmpq $native_iret,%rax
-#endif
+        cmpq $native_irq_return_iret,%rax
         jne do_double_fault             /* This shouldn't happen... */
-1:
         movq PER_CPU_VAR(kernel_stack),%rax
         subq $(6*8-KERNEL_STACK_OFFSET),%rax    /* Reset to original stack */
         movq %rax,RSP(%rdi)
@@ -1428,7 +1420,7 @@ error_sti:
  */
 error_kernelspace:
         incl %ebx
-        leaq irq_return_iret(%rip),%rcx
+        leaq native_irq_return_iret(%rip),%rcx
         cmpq %rcx,RIP+8(%rsp)
         je error_swapgs
         movl %ecx,%eax  /* zero extend */
diff --git a/arch/x86/kernel/paravirt_patch_64.c b/arch/x86/kernel/paravirt_patch_64.c
index 3f08f34f93eb..a1da6737ba5b 100644
--- a/arch/x86/kernel/paravirt_patch_64.c
+++ b/arch/x86/kernel/paravirt_patch_64.c
@@ -6,7 +6,6 @@ DEF_NATIVE(pv_irq_ops, irq_disable, "cli");
 DEF_NATIVE(pv_irq_ops, irq_enable, "sti");
 DEF_NATIVE(pv_irq_ops, restore_fl, "pushq %rdi; popfq");
 DEF_NATIVE(pv_irq_ops, save_fl, "pushfq; popq %rax");
-DEF_NATIVE(pv_cpu_ops, iret, "iretq");
 DEF_NATIVE(pv_mmu_ops, read_cr2, "movq %cr2, %rax");
 DEF_NATIVE(pv_mmu_ops, read_cr3, "movq %cr3, %rax");
 DEF_NATIVE(pv_mmu_ops, write_cr3, "movq %rdi, %cr3");
@@ -50,7 +49,6 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
                 PATCH_SITE(pv_irq_ops, save_fl);
                 PATCH_SITE(pv_irq_ops, irq_enable);
                 PATCH_SITE(pv_irq_ops, irq_disable);
-                PATCH_SITE(pv_cpu_ops, iret);
                 PATCH_SITE(pv_cpu_ops, irq_enable_sysexit);
                 PATCH_SITE(pv_cpu_ops, usergs_sysret32);
                 PATCH_SITE(pv_cpu_ops, usergs_sysret64);