FAILED: patch "[PATCH] powerpc/powernv: Fix save/restore of SPRG3 on entry/exit from" failed to apply to 4.14-stable tree

FAILED: patch "[PATCH] powerpc/powernv: Fix save/restore of SPRG3 on entry/exit from" failed to apply to 4.14-stable tree

[gregkh]

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From b03897cf318dfc47de33a7ecbc7655584266f034 Mon Sep 17 00:00:00 2001
From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
Date: Wed, 18 Jul 2018 14:03:16 +0530
Subject: [PATCH] powerpc/powernv: Fix save/restore of SPRG3 on entry/exit from
 stop (idle)

On 64-bit servers, SPRN_SPRG3 and its userspace read-only mirror
SPRN_USPRG3 are used as userspace VDSO write and read registers
respectively.

SPRN_SPRG3 is lost when we enter stop4 and above, and is currently not
restored.  As a result, any read from SPRN_USPRG3 returns zero on an
exit from stop4 (Power9 only) and above.

Thus in this situation, on POWER9, any call from sched_getcpu() always
returns zero, as on powerpc, we call __kernel_getcpu() which relies
upon SPRN_USPRG3 to report the CPU and NUMA node information.

Fix this by restoring SPRN_SPRG3 on wake up from a deep stop state
with the sprg_vdso value that is cached in PACA.

Fixes: e1c1cfed5432 ("powerpc/powernv: Save/Restore additional SPRs for stop4 cpuidle")
Cc: stable@vger.kernel.org # v4.14+
Reported-by: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index e734f6e45abc..689306118b48 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -144,7 +144,9 @@ power9_restore_additional_sprs:
 	mtspr	SPRN_MMCR1, r4
 
 	ld	r3, STOP_MMCR2(r13)
+	ld	r4, PACA_SPRG_VDSO(r13)
 	mtspr	SPRN_MMCR2, r3
+	mtspr	SPRN_SPRG3, r4
 	blr
 
 /*

[PATCH] powerpc/powernv : Save/Restore SPRG3 on entry/exit from stop.

[Gautham R. Shenoy]

From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>

[ Upstream commit b03897cf318dfc47de33a7ecbc7655584266f034 ]

On 64-bit servers, SPRN_SPRG3 and its userspace read-only mirror
SPRN_USPRG3 are used as userspace VDSO write and read registers
respectively.

SPRN_SPRG3 is lost when we enter stop4 and above, and is currently not
restored.  As a result, any read from SPRN_USPRG3 returns zero on an
exit from stop4 and above.

Thus in this situation, on POWER9, any call from sched_getcpu() always
returns zero, as on powerpc, we call __kernel_getcpu() which relies
upon SPRN_USPRG3 to report the CPU and NUMA node information.

Fix this by restoring SPRN_SPRG3 on wake up from a deep stop state
with the sprg_vdso value that is cached in PACA.

Fixes: e1c1cfed5432 ("powerpc/powernv: Save/Restore additional SPRs
for stop4 cpuidle")

Reported-by: Florian Weimer <fweimer@redhat.com>
Cc: <stable@vger.kernel.org> # 4.14
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/kernel/idle_book3s.S | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index 1125c9b..8959057 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -140,6 +140,8 @@ power9_restore_additional_sprs:
 	ld	r4, STOP_MMCR2(r13)
 	mtspr	SPRN_MMCR1, r3
 	mtspr	SPRN_MMCR2, r4
+	ld	r4, PACA_SPRG_VDSO(r13)
+	mtspr	SPRN_SPRG3, r4
 	blr
 
 /*
-- 
1.9.4

Re: [PATCH] powerpc/powernv : Save/Restore SPRG3 on entry/exit from stop.

[Greg KH]

On Mon, Jul 23, 2018 at 11:00:55AM +0530, Gautham R. Shenoy wrote:
> From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
> 
> [ Upstream commit b03897cf318dfc47de33a7ecbc7655584266f034 ]
> 
> On 64-bit servers, SPRN_SPRG3 and its userspace read-only mirror
> SPRN_USPRG3 are used as userspace VDSO write and read registers
> respectively.
> 
> SPRN_SPRG3 is lost when we enter stop4 and above, and is currently not
> restored.  As a result, any read from SPRN_USPRG3 returns zero on an
> exit from stop4 and above.
> 
> Thus in this situation, on POWER9, any call from sched_getcpu() always
> returns zero, as on powerpc, we call __kernel_getcpu() which relies
> upon SPRN_USPRG3 to report the CPU and NUMA node information.
> 
> Fix this by restoring SPRN_SPRG3 on wake up from a deep stop state
> with the sprg_vdso value that is cached in PACA.
> 
> Fixes: e1c1cfed5432 ("powerpc/powernv: Save/Restore additional SPRs
> for stop4 cpuidle")
> 
> Reported-by: Florian Weimer <fweimer@redhat.com>
> Cc: <stable@vger.kernel.org> # 4.14
> Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
> Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---
>  arch/powerpc/kernel/idle_book3s.S | 2 ++
>  1 file changed, 2 insertions(+)

What stable tree(s) do you want this applied to?

thanks,

greg k-h

Re: [PATCH] powerpc/powernv : Save/Restore SPRG3 on entry/exit from stop.

[Greg KH]

On Mon, Jul 23, 2018 at 08:16:28AM +0200, Greg KH wrote:
> On Mon, Jul 23, 2018 at 11:00:55AM +0530, Gautham R. Shenoy wrote:
> > From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
> > 
> > [ Upstream commit b03897cf318dfc47de33a7ecbc7655584266f034 ]
> > 
> > On 64-bit servers, SPRN_SPRG3 and its userspace read-only mirror
> > SPRN_USPRG3 are used as userspace VDSO write and read registers
> > respectively.
> > 
> > SPRN_SPRG3 is lost when we enter stop4 and above, and is currently not
> > restored.  As a result, any read from SPRN_USPRG3 returns zero on an
> > exit from stop4 and above.
> > 
> > Thus in this situation, on POWER9, any call from sched_getcpu() always
> > returns zero, as on powerpc, we call __kernel_getcpu() which relies
> > upon SPRN_USPRG3 to report the CPU and NUMA node information.
> > 
> > Fix this by restoring SPRN_SPRG3 on wake up from a deep stop state
> > with the sprg_vdso value that is cached in PACA.
> > 
> > Fixes: e1c1cfed5432 ("powerpc/powernv: Save/Restore additional SPRs
> > for stop4 cpuidle")
> > 
> > Reported-by: Florian Weimer <fweimer@redhat.com>
> > Cc: <stable@vger.kernel.org> # 4.14
> > Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
> > Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
> > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> > ---
> >  arch/powerpc/kernel/idle_book3s.S | 2 ++
> >  1 file changed, 2 insertions(+)
> 
> What stable tree(s) do you want this applied to?

I've now guessed that it is 4.14.y.  If that's not the case, please let
me know.

greg k-h

Re: [PATCH] powerpc/powernv : Save/Restore SPRG3 on entry/exit from stop.

[Gautham R Shenoy]

Hello Greg,

On Mon, Jul 23, 2018 at 09:53:50AM +0200, Greg KH wrote:
> On Mon, Jul 23, 2018 at 08:16:28AM +0200, Greg KH wrote:
> > On Mon, Jul 23, 2018 at 11:00:55AM +0530, Gautham R. Shenoy wrote:
> > > From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
> > > 
> > > [ Upstream commit b03897cf318dfc47de33a7ecbc7655584266f034 ]
> > > 
> > > On 64-bit servers, SPRN_SPRG3 and its userspace read-only mirror
> > > SPRN_USPRG3 are used as userspace VDSO write and read registers
> > > respectively.
> > > 
> > > SPRN_SPRG3 is lost when we enter stop4 and above, and is currently not
> > > restored.  As a result, any read from SPRN_USPRG3 returns zero on an
> > > exit from stop4 and above.
> > > 
> > > Thus in this situation, on POWER9, any call from sched_getcpu() always
> > > returns zero, as on powerpc, we call __kernel_getcpu() which relies
> > > upon SPRN_USPRG3 to report the CPU and NUMA node information.
> > > 
> > > Fix this by restoring SPRN_SPRG3 on wake up from a deep stop state
> > > with the sprg_vdso value that is cached in PACA.
> > > 
> > > Fixes: e1c1cfed5432 ("powerpc/powernv: Save/Restore additional SPRs
> > > for stop4 cpuidle")
> > > 
> > > Reported-by: Florian Weimer <fweimer@redhat.com>
> > > Cc: <stable@vger.kernel.org> # 4.14
> > > Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
> > > Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
> > > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> > > ---
> > >  arch/powerpc/kernel/idle_book3s.S | 2 ++
> > >  1 file changed, 2 insertions(+)
> > 
> > What stable tree(s) do you want this applied to?
> 
> I've now guessed that it is 4.14.y.  If that's not the case, please let
> me know.

Yes, this backport is for 4.14.y. The upstream commit cleanly applies
on 4.15.18 and 4.16.18.

> 
> greg k-h
> 

--
Thanks and Regards
gautham.