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Commit 17065671 authored by Shreyas B. Prabhu's avatar Shreyas B. Prabhu Committed by Michael Ellerman
Browse files

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: default avatarPaul Mackerras <paulus@samba.org>
Reviewed-by: default avatarGautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: default avatarShreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent bfd1b7ae

arch/powerpc/kernel/exceptions-64s.S

+4 −24
Original line number Diff line number Diff line
@@ -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)

arch/powerpc/kernel/idle_power7.S

+42 −30
Original line number Diff line number Diff line
@@ -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