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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
Download Patch File Download Diff File Expand all files Collapse all files

28
arch/powerpc/kernel/exceptions-64s.S
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@@ -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)