[PATCH 0/2] non maskable interrupt reentrancy fixes for OPAL

[PATCH 0/2] non maskable interrupt reentrancy fixes for OPAL

[Nicholas Piggin]

Hi,

These fixes are more minimal, and split up properly since last post.
Also accounted for Ben's comment of using HSRRs rather than disabling
RI for OPAL_CALL.

This will still increase cost of opal calls a bit due to new mtmsr in
FIXUP_ENDIAN return.

I have a few more patches that reduce overhead quite a bit, but they
won't be suitable for 4.12, so I'll send those out after merge window.

Thanks,
Nick

Nicholas Piggin (2):
  powerpc/64s: Fix FIXUP_ENDIAN non-maskable interrupt reentrancy
  powerpc/64s: Fix OPAL_CALL non-maskable interrupt reentrancy

 arch/powerpc/boot/ppc_asm.h                    | 12 +++++++-----
 arch/powerpc/include/asm/ppc_asm.h             | 11 +++++++----
 arch/powerpc/platforms/powernv/opal-wrappers.S |  6 +++---
 3 files changed, 17 insertions(+), 12 deletions(-)

-- 
2.11.0

[PATCH 1/2] powerpc/64s: Fix FIXUP_ENDIAN non-maskable interrupt reentrancy

[Nicholas Piggin]

FIXUP_ENDIAN uses SRR[01] with MSR_RI=1, which gets corrupted if there
is an interleaving system reset or machine check interrupt.

Set MSR_RI=0 before setting SRRs. The rfid will restore MSR.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/boot/ppc_asm.h        | 12 +++++++-----
 arch/powerpc/include/asm/ppc_asm.h | 11 +++++++----
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/boot/ppc_asm.h b/arch/powerpc/boot/ppc_asm.h
index b03373d8b386..68e388ee94fe 100644
--- a/arch/powerpc/boot/ppc_asm.h
+++ b/arch/powerpc/boot/ppc_asm.h
@@ -67,13 +67,15 @@
 #define MSR_LE		0x0000000000000001
 
 #define FIXUP_ENDIAN						   \
-	tdi   0, 0, 0x48; /* Reverse endian of b . + 8		*/ \
-	b     $+36;	  /* Skip trampoline if endian is good	*/ \
-	.long 0x05009f42; /* bcl 20,31,$+4			*/ \
-	.long 0xa602487d; /* mflr r10				*/ \
-	.long 0x1c004a39; /* addi r10,r10,28			*/ \
+	tdi   0,0,0x48;	  /* Reverse endian of b . + 8		*/ \
+	b     $+44;	  /* Skip trampoline if endian is good	*/ \
 	.long 0xa600607d; /* mfmsr r11				*/ \
 	.long 0x01006b69; /* xori r11,r11,1			*/ \
+	.long 0x00004039; /* li r10,0				*/ \
+	.long 0x6401417d; /* mtmsrd r10,1			*/ \
+	.long 0x05009f42; /* bcl 20,31,$+4			*/ \
+	.long 0xa602487d; /* mflr r10				*/ \
+	.long 0x14004a39; /* addi r10,r10,20			*/ \
 	.long 0xa6035a7d; /* mtsrr0 r10				*/ \
 	.long 0xa6037b7d; /* mtsrr1 r11				*/ \
 	.long 0x2400004c  /* rfid				*/
diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index 359c44341761..6baeeb9acd0d 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -770,15 +770,18 @@ END_FTR_SECTION_IFCLR(CPU_FTR_601)
 #else
 #define FIXUP_ENDIAN						   \
 	tdi   0,0,0x48;	  /* Reverse endian of b . + 8		*/ \
-	b     $+36;	  /* Skip trampoline if endian is good	*/ \
-	.long 0x05009f42; /* bcl 20,31,$+4			*/ \
-	.long 0xa602487d; /* mflr r10				*/ \
-	.long 0x1c004a39; /* addi r10,r10,28			*/ \
+	b     $+44;	  /* Skip trampoline if endian is good	*/ \
 	.long 0xa600607d; /* mfmsr r11				*/ \
 	.long 0x01006b69; /* xori r11,r11,1			*/ \
+	.long 0x00004039; /* li r10,0				*/ \
+	.long 0x6401417d; /* mtmsrd r10,1			*/ \
+	.long 0x05009f42; /* bcl 20,31,$+4			*/ \
+	.long 0xa602487d; /* mflr r10				*/ \
+	.long 0x14004a39; /* addi r10,r10,20			*/ \
 	.long 0xa6035a7d; /* mtsrr0 r10				*/ \
 	.long 0xa6037b7d; /* mtsrr1 r11				*/ \
 	.long 0x2400004c  /* rfid				*/
+
 #endif /* !CONFIG_PPC_BOOK3E */
 
 #endif /*  __ASSEMBLY__ */
-- 
2.11.0

Re: [1/2] powerpc/64s: Fix FIXUP_ENDIAN non-maskable interrupt reentrancy

[Michael Ellerman]

On Mon, 2017-05-01 at 12:01:09 UTC, Nicholas Piggin wrote:
> FIXUP_ENDIAN uses SRR[01] with MSR_RI=1, which gets corrupted if there
> is an interleaving system reset or machine check interrupt.
> 
> Set MSR_RI=0 before setting SRRs. The rfid will restore MSR.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/f1fe5252018075e18d7f0c0e23ee17

cheers

[PATCH 2/2] powerpc/64s: Fix OPAL_CALL non-maskable interrupt reentrancy

[Nicholas Piggin]

OPAL_CALL uses SRR[01] with MSR_RI=1, which gets corrupted if there
is an interleaving system reset or machine check interrupt.

Use HSRR[01] instead, which does not require MSR_RI=0.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/platforms/powernv/opal-wrappers.S | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
index f620572f891f..4ca6c26a56d5 100644
--- a/arch/powerpc/platforms/powernv/opal-wrappers.S
+++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
@@ -99,10 +99,10 @@ opal_return:
 	lwz	r4,8(r1);
 	ld	r5,PPC_LR_STKOFF(r1);
 	ld	r6,PACASAVEDMSR(r13);
-	mtspr	SPRN_SRR0,r5;
-	mtspr	SPRN_SRR1,r6;
 	mtcr	r4;
-	rfid
+	mtspr	SPRN_HSRR0,r5;
+	mtspr	SPRN_HSRR1,r6;
+	hrfid
 
 opal_real_call:
 	mfcr	r11
-- 
2.11.0