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Commit a2b5e056 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/powernv: Fix SMT4 forcing idle code 



The PSSCR value is not stored to PACA_REQ_PSSCR if the CPU does not
have the XER[SO] bug.

Fix this by storing up-front, outside the workaround code. The initial
test is not required because it is a slow path.

The workaround is made to depend on CONFIG_KVM_BOOK3S_HV_POSSIBLE, to
match pnv_power9_force_smt4_catch() where it is used. Drop the comment
on pnv_power9_force_smt4_catch() as it's no longer true.

Fixes: 7672691a ("powerpc/powernv: Provide a way to force a core into SMT4 mode")
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent b6f534d1

arch/powerpc/kernel/idle_book3s.S

+5 −4
Original line number Diff line number Diff line
@@ -442,20 +442,20 @@ _GLOBAL(power9_offline_stop) 
 * r3 contains desired PSSCR register value.

 */

_GLOBAL(power9_idle_stop)

BEGIN_FTR_SECTION

	lwz	r5, PACA_DONT_STOP(r13)

	cmpwi	r5, 0

	bne	1f

	std	r3, PACA_REQ_PSSCR(r13)

#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE

BEGIN_FTR_SECTION

	sync

	lwz	r5, PACA_DONT_STOP(r13)

	cmpwi	r5, 0

	bne	1f

END_FTR_SECTION_IFSET(CPU_FTR_P9_TM_XER_SO_BUG)

#endif

	mtspr 	SPRN_PSSCR,r3

	LOAD_REG_ADDR(r4,power_enter_stop)

	b	pnv_powersave_common

	/* No return */

#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE

1:

	/*

	 * We get here when TM / thread reconfiguration bug workaround
@@ -465,6 +465,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_P9_TM_XER_SO_BUG) 
	li	r3, 0

	std	r3, PACA_REQ_PSSCR(r13)

	blr		/* return 0 for wakeup cause / SRR1 value */

#endif



/*

 * On waking up from stop 0,1,2 with ESL=1 on POWER9 DD1,

arch/powerpc/platforms/powernv/idle.c

+0 −4
Original line number Diff line number Diff line
@@ -397,10 +397,6 @@ void power9_idle(void) 
 * all other threads not to stop, and sending a message to any

 * that are in a stop state.

 * Must be called with preemption disabled.

 *

 * DO NOT call this unless cpu_has_feature(CPU_FTR_P9_TM_XER_SO_BUG) is

 * true; otherwise this function will hang the system, due to the

 * optimization in power9_idle_stop.

 */

void pnv_power9_force_smt4_catch(void)

{