powerpc/kvm: make hypervisor state restore a function

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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 8bcc1b457115867e93ace2317f203e1cda100352..612a65b2b99e53b16f5fd6c5fdd3f9c13d64e695 100644 (file)
--- 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 705c867306ea6c49d10b20c35c220bef06e7f123..d5def062a5448cf9159cdfcdb44217c386920fb7 100644 (file)
--- 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
         * 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