--- v5
+++ v3
@@ -1,26 +1,212 @@
+In the current code, when the thread wakes up in reset vector, some
+of the state restore code and check for whether a thread needs to
+branch to kvm is duplicated. Reorder the code such that this
+duplication is avoided.
+
+At a higher level this is what the change looks like-
+
+Before this patch -
+power7_wakeup_tb_loss:
+ restore hypervisor state
+ if (thread needed by kvm)
+ goto kvm_start_guest
+ restore nvgprs, cr, pc
+ rfid to process context
+
+power7_wakeup_loss:
+ restore nvgprs, cr, pc
+ rfid to process context
+
+reset vector:
+ if (waking from deep idle states)
+ goto power7_wakeup_tb_loss
+ else
+ if (thread needed by kvm)
+ goto kvm_start_guest
+ goto power7_wakeup_loss
+
+After this patch -
+power7_wakeup_tb_loss:
+ restore hypervisor state
+ return
+
+power7_restore_hyp_resource():
+ if (waking from deep idle states)
+ goto power7_wakeup_tb_loss
+ return
+
+power7_wakeup_loss:
+ restore nvgprs, cr, pc
+ rfid to process context
+
+reset vector:
+ power7_restore_hyp_resource()
+ if (thread needed by kvm)
+ goto kvm_start_guest
+ goto power7_wakeup_loss
+
+Reviewed-by: Paul Mackerras <paulus@samba.org>
+Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
---
--No changes in v5
-
-Changes in v4
+Changes in v3:
=============
-- New in v4
-
- arch/powerpc/kernel/idle_power7.S | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
+- Retaining GET_PACA(r13) in System Reset vector instead of moving it
+ to power7_restore_hyp_resource
+- Added comments indicating entry conditions for power7_restore_hyp_resource
+- Improved comments around return statements
+
+
+ arch/powerpc/kernel/exceptions-64s.S | 28 ++------------
+ arch/powerpc/kernel/idle_power7.S | 72 +++++++++++++++++++++---------------
+ 2 files changed, 46 insertions(+), 54 deletions(-)
+
+diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
+index 4c94406..4a74d6a 100644
+--- a/arch/powerpc/kernel/exceptions-64s.S
++++ b/arch/powerpc/kernel/exceptions-64s.S
+@@ -107,25 +107,9 @@ BEGIN_FTR_SECTION
+ beq 9f
+
+ cmpwi cr3,r13,2
+-
+- /*
+- * Check if last bit of HSPGR0 is set. This indicates whether we are
+- * waking up from winkle.
+- */
+ GET_PACA(r13)
+- clrldi r5,r13,63
+- clrrdi r13,r13,1
+- cmpwi cr4,r5,1
+- mtspr SPRN_HSPRG0,r13
++ bl power7_restore_hyp_resource
+
+- lbz r0,PACA_THREAD_IDLE_STATE(r13)
+- cmpwi cr2,r0,PNV_THREAD_NAP
+- bgt cr2,8f /* Either sleep or Winkle */
+-
+- /* Waking up from nap should not cause hypervisor state loss */
+- bgt cr3,.
+-
+- /* Waking up from nap */
+ li r0,PNV_THREAD_RUNNING
+ stb r0,PACA_THREAD_IDLE_STATE(r13) /* Clear thread state */
+
+@@ -143,13 +127,9 @@ BEGIN_FTR_SECTION
+
+ /* Return SRR1 from power7_nap() */
+ mfspr r3,SPRN_SRR1
+- beq cr3,2f
+- b power7_wakeup_noloss
+-2: b power7_wakeup_loss
+-
+- /* Fast Sleep wakeup on PowerNV */
+-8: GET_PACA(r13)
+- b power7_wakeup_tb_loss
++ blt cr3,2f
++ b power7_wakeup_loss
++2: b power7_wakeup_noloss
+
+ 9:
+ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S
-index 470ceeb..705c867 100644
+index 470ceeb..db59613 100644
--- a/arch/powerpc/kernel/idle_power7.S
+++ b/arch/powerpc/kernel/idle_power7.S
-@@ -252,7 +252,7 @@ _GLOBAL(power7_sleep)
- /* No return */
-
- _GLOBAL(power7_winkle)
-- li r3,3
-+ li r3,PNV_THREAD_WINKLE
- li r4,1
- b power7_powersave_common
- /* No return */
+@@ -276,6 +276,39 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66); \
+ 20: nop;
+
+
++/*
++ * Called from reset vector. Check whether we have woken up with
++ * hypervisor state loss. If yes, restore hypervisor state and return
++ * back to reset vector.
++ *
++ * r13 - Contents of HSPRG0
++ * cr3 - set to gt if waking up with partial/complete hypervisor state loss
++ */
++_GLOBAL(power7_restore_hyp_resource)
++ /*
++ * Check if last bit of HSPGR0 is set. This indicates whether we are
++ * waking up from winkle.
++ */
++ clrldi r5,r13,63
++ clrrdi r13,r13,1
++ cmpwi cr4,r5,1
++ mtspr SPRN_HSPRG0,r13
++
++ lbz r0,PACA_THREAD_IDLE_STATE(r13)
++ cmpwi cr2,r0,PNV_THREAD_NAP
++ bgt cr2,power7_wakeup_tb_loss /* Either sleep or Winkle */
++
++ /*
++ * We fall through here if PACA_THREAD_IDLE_STATE shows we are waking
++ * up from nap. At this stage CR3 shouldn't contains 'gt' since that
++ * indicates we are waking with hypervisor state loss from nap.
++ */
++ bgt cr3,.
++
++ blr /* Return back to System Reset vector from where
++ power7_restore_hyp_resource was invoked */
++
++
+ _GLOBAL(power7_wakeup_tb_loss)
+ ld r2,PACATOC(r13);
+ ld r1,PACAR1(r13)
+@@ -284,11 +317,13 @@ _GLOBAL(power7_wakeup_tb_loss)
+ * and they are restored before switching to the process context. Hence
+ * until they are restored, they are free to be used.
+ *
+- * Save SRR1 in a NVGPR as it might be clobbered in opal_call_realmode
+- * (called in CHECK_HMI_INTERRUPT). SRR1 is required to determine the
+- * wakeup reason if we branch to kvm_start_guest.
++ * Save SRR1 and LR in NVGPRs as they might be clobbered in
++ * opal_call_realmode (called in CHECK_HMI_INTERRUPT). SRR1 is required
++ * to determine the wakeup reason if we branch to kvm_start_guest. LR
++ * is required to return back to reset vector after hypervisor state
++ * restore is complete.
+ */
+-
++ mflr r17
+ mfspr r16,SPRN_SRR1
+ BEGIN_FTR_SECTION
+ CHECK_HMI_INTERRUPT
+@@ -438,33 +473,10 @@ common_exit:
+
+ hypervisor_state_restored:
+
+- li r5,PNV_THREAD_RUNNING
+- stb r5,PACA_THREAD_IDLE_STATE(r13)
+-
+ mtspr SPRN_SRR1,r16
+-#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+- li r0,KVM_HWTHREAD_IN_KERNEL
+- stb r0,HSTATE_HWTHREAD_STATE(r13)
+- /* Order setting hwthread_state vs. testing hwthread_req */
+- sync
+- lbz r0,HSTATE_HWTHREAD_REQ(r13)
+- cmpwi r0,0
+- beq 6f
+- b kvm_start_guest
+-6:
+-#endif
+-
+- REST_NVGPRS(r1)
+- REST_GPR(2, r1)
+- ld r3,_CCR(r1)
+- ld r4,_MSR(r1)
+- ld r5,_NIP(r1)
+- addi r1,r1,INT_FRAME_SIZE
+- mtcr r3
+- mfspr r3,SPRN_SRR1 /* Return SRR1 */
+- mtspr SPRN_SRR1,r4
+- mtspr SPRN_SRR0,r5
+- rfid
++ mtlr r17
++ blr /* Return back to System Reset vector from where
++ power7_restore_hyp_resource was invoked */
+
+ fastsleep_workaround_at_exit:
+ li r3,1
--
-2.1.4
+2.4.11