[PATCH v6 02/11] powerpc/kvm: make hypervisor state restore a function

[Shreyas B. Prabhu]

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 
Reviewed-by: Gautham R. Shenoy 
Signed-off-by: Shreyas B. Prabhu 
---
- No changes since v3

Changes in v3:
=
- 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 705c867..d5def06 100644
--- a/arch/powerpc/kernel/idle_power7.S
+++ b/arch/powerpc/kernel/idle_power7.S
@@ -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 

[PATCH v6 02/11] powerpc/kvm: make hypervisor state restore a function

[Shreyas B. Prabhu]

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 
Reviewed-by: Gautham R. Shenoy 
Signed-off-by: Shreyas B. Prabhu 
---
- No changes since v3

Changes in v3:
=
- 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 705c867..d5def06 100644
--- a/arch/powerpc/kernel/idle_power7.S
+++ b/arch/powerpc/kernel/idle_power7.S
@@ -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