Merge branch 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6

* 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6:
  [S390] guest page hinting light
  [S390] tty3270: fix put_char fail/success conversion.
  [S390] compat ptrace cleanup
  [S390] s390mach compile warning
  [S390] cio: Fix parsing mechanism for blacklisted devices.
  [S390] cio: Remove cio_msg kernel parameter.
  [S390] s390-kvm: leave sie context on work. Removes preemption requirement
  [S390] s390: Optimize user and work TIF check

1 files changed, 42 insertions, 15 deletions

diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 5a4a7bcd2bba..fee10177dbfc 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -271,8 +271,6 @@ sysc_noemu:
         stg     %r2,SP_R2(%r15) # store return value (change R2 on stack)
 
 sysc_return:
-        tm      SP_PSW+1(%r15),0x01     # returning to user ?
-        jno     sysc_restore
         tm      __TI_flags+7(%r9),_TIF_WORK_SVC
         jnz     sysc_work       # there is work to do (signals etc.)
 sysc_restore:
@@ -304,6 +302,8 @@ sysc_work_loop:
 # One of the work bits is on. Find out which one.
 #
 sysc_work:
+        tm      SP_PSW+1(%r15),0x01     # returning to user ?
+        jno     sysc_restore
         tm      __TI_flags+7(%r9),_TIF_MCCK_PENDING
         jo      sysc_mcck_pending
         tm      __TI_flags+7(%r9),_TIF_NEED_RESCHED
@@ -585,12 +585,6 @@ io_no_vtime:
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
         brasl   %r14,do_IRQ             # call standard irq handler
 io_return:
-        tm      SP_PSW+1(%r15),0x01     # returning to user ?
-#ifdef CONFIG_PREEMPT
-        jno     io_preempt              # no -> check for preemptive scheduling
-#else
-        jno     io_restore              # no-> skip resched & signal
-#endif
         tm      __TI_flags+7(%r9),_TIF_WORK_INT
         jnz     io_work                 # there is work to do (signals etc.)
 io_restore:
@@ -612,10 +606,41 @@ io_restore_trace_psw:
         .quad   0, io_restore_trace
 #endif
 
-#ifdef CONFIG_PREEMPT
-io_preempt:
+#
+# There is work todo, we need to check if we return to userspace, then
+# check, if we are in SIE, if yes leave it
+#
+io_work:
+        tm      SP_PSW+1(%r15),0x01     # returning to user ?
+#ifndef CONFIG_PREEMPT
+#if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)
+        jnz     io_work_user            # yes -> no need to check for SIE
+        la      %r1, BASED(sie_opcode)  # we return to kernel here
+        lg      %r2, SP_PSW+8(%r15)
+        clc     0(2,%r1), 0(%r2)        # is current instruction = SIE?
+        jne     io_restore              # no-> return to kernel
+        lg      %r1, SP_PSW+8(%r15)     # yes-> add 4 bytes to leave SIE
+        aghi    %r1, 4
+        stg     %r1, SP_PSW+8(%r15)
+        j       io_restore              # return to kernel
+#else
+        jno     io_restore              # no-> skip resched & signal
+#endif
+#else
+        jnz     io_work_user            # yes -> do resched & signal
+#if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)
+        la      %r1, BASED(sie_opcode)
+        lg      %r2, SP_PSW+8(%r15)
+        clc     0(2,%r1), 0(%r2)        # is current instruction = SIE?
+        jne     0f                      # no -> leave PSW alone
+        lg      %r1, SP_PSW+8(%r15)     # yes-> add 4 bytes to leave SIE
+        aghi    %r1, 4
+        stg     %r1, SP_PSW+8(%r15)
+0:
+#endif
+        # check for preemptive scheduling
         icm     %r0,15,__TI_precount(%r9)
-        jnz     io_restore
+        jnz     io_restore              # preemption is disabled
         # switch to kernel stack
         lg      %r1,SP_R15(%r15)
         aghi    %r1,-SP_SIZE
@@ -629,10 +654,7 @@ io_resume_loop:
         jg      preempt_schedule_irq
 #endif
 
-#
-# switch to kernel stack, then check TIF bits
-#
-io_work:
+io_work_user:
         lg      %r1,__LC_KERNEL_STACK
         aghi    %r1,-SP_SIZE
         mvc     SP_PTREGS(__PT_SIZE,%r1),SP_PTREGS(%r15)
@@ -653,6 +675,11 @@ io_work_loop:
         j       io_restore
 io_work_done:
 
+#if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)
+sie_opcode:
+        .long 0xb2140000
+#endif
+
 #
 # _TIF_MCCK_PENDING is set, call handler
 #