2016-11-22 18:06:54

by Gautham R Shenoy

Subject: [PATCH] powernv: Clear SPRN_PSSCR when a POWER9 CPU comes online

From: "Gautham R. Shenoy" <[email protected]>

Ensure that PSSCR is set to a safe value corresponding to no
state-loss each time a POWER9 CPU comes online.

Signed-off-by: Gautham R. Shenoy <[email protected]>
---
arch/powerpc/kernel/cpu_setup_power.S | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S
index 52ff3f0..37ad045 100644
--- a/arch/powerpc/kernel/cpu_setup_power.S
+++ b/arch/powerpc/kernel/cpu_setup_power.S
@@ -96,6 +96,7 @@ _GLOBAL(__setup_cpu_power9)
mtlr r11
beqlr
li r0,0
+ mtspr SPRN_PSSCR,r0
mtspr SPRN_LPID,r0
mfspr r3,SPRN_LPCR
ori r3, r3, LPCR_PECEDH
@@ -116,6 +117,7 @@ _GLOBAL(__restore_cpu_power9)
mtlr r11
beqlr
li r0,0
+ mtspr SPRN_PSSCR,r0
mtspr SPRN_LPID,r0
mfspr r3,SPRN_LPCR
ori r3, r3, LPCR_PECEDH
--
1.9.4

2016-11-22 23:30:45

by Michael Ellerman

Subject: Re: [PATCH] powernv: Clear SPRN_PSSCR when a POWER9 CPU comes online

"Gautham R. Shenoy" <[email protected]> writes:

> From: "Gautham R. Shenoy" <[email protected]>
>
> Ensure that PSSCR is set to a safe value corresponding to no
> state-loss each time a POWER9 CPU comes online.

Is this a bug fix? I can't tell from the change log.

cheers

2016-11-22 23:35:41

by Michael Neuling

Subject: Re: [PATCH] powernv: Clear SPRN_PSSCR when a POWER9 CPU comes online

On Wed, 2016-11-23 at 10:30 +1100, Michael Ellerman wrote:
> "Gautham R. Shenoy" <[email protected]> writes:
>
> > From: "Gautham R. Shenoy" <[email protected]>
> >
> > Ensure that PSSCR is set to a safe value corresponding to no
> > state-loss each time a POWER9 CPU comes online.
>
> Is this a bug fix? I can't tell from the change log.

There are no known bugs it's fixing.  

It's just safer to run with a known default value, rather than what we randomly
inherit from previous firmware.

Mikey

2016-11-23 00:32:58

by Michael Neuling

Subject: Re: [PATCH] powernv: Clear SPRN_PSSCR when a POWER9 CPU comes online

On Tue, 2016-11-22 at 23:36 +0530, Gautham R. Shenoy wrote:
> From: "Gautham R. Shenoy" <[email protected]>
>
> Ensure that PSSCR is set to a safe value corresponding to no
> state-loss each time a POWER9 CPU comes online.
>
> Signed-off-by: Gautham R. Shenoy <[email protected]>

Tested here on my configuration... FWIW

Acked-By: Michael Neuling <[email protected]>

> ---
>  arch/powerpc/kernel/cpu_setup_power.S | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/powerpc/kernel/cpu_setup_power.S
> b/arch/powerpc/kernel/cpu_setup_power.S
> index 52ff3f0..37ad045 100644
> --- a/arch/powerpc/kernel/cpu_setup_power.S
> +++ b/arch/powerpc/kernel/cpu_setup_power.S
> @@ -96,6 +96,7 @@ _GLOBAL(__setup_cpu_power9)
>   mtlr r11
>   beqlr
>   li r0,0
> + mtspr SPRN_PSSCR,r0
>   mtspr SPRN_LPID,r0
>   mfspr r3,SPRN_LPCR
>   ori r3, r3, LPCR_PECEDH
> @@ -116,6 +117,7 @@ _GLOBAL(__restore_cpu_power9)
>   mtlr r11
>   beqlr
>   li r0,0
> + mtspr SPRN_PSSCR,r0
>   mtspr SPRN_LPID,r0
>   mfspr   r3,SPRN_LPCR
>   ori r3, r3, LPCR_PECEDH

2016-11-28 12:15:36

by Michael Ellerman

Subject: Re: powernv: Clear SPRN_PSSCR when a POWER9 CPU comes online

On Tue, 2016-11-22 at 18:06:40 UTC, "Gautham R. Shenoy" wrote:
> From: "Gautham R. Shenoy" <[email protected]>
>
> Ensure that PSSCR is set to a safe value corresponding to no
> state-loss each time a POWER9 CPU comes online.
>
> Signed-off-by: Gautham R. Shenoy <[email protected]>
> Acked-By: Michael Neuling <[email protected]>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/378f96d3cd442d5cb8e2692d8767a4

cheers