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powerpc/kvm: make hypervisor state restore a function

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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>
This commit is contained in:
Shreyas B. Prabhu 2016-07-08 11:50:44 +05:30 committed by Michael Ellerman
parent bfd1b7ae5e
commit 1706567117
2 changed files with 46 additions and 54 deletions
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28
arch/powerpc/kernel/exceptions-64s.S
View File

@ -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)

72
arch/powerpc/kernel/idle_power7.S
View File

@ -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