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From:   Christophe Leroy <christophe.leroy@csgroup.eu>
Subject: [PATCH v3 3/3] powerpc: Define and use MSR_RI only on non booke/40x
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, npiggin@gmail.com
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Date:   Mon, 23 Aug 2021 08:24:22 +0000 (UTC)
Precedence: bulk

40x and BOOKE don't have MSR_RI.

Define MSR_RI only for platforms where it exists. For the other ones,
defines it as BUILD_BUG for C and do not define it for ASM.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v3: Fixes kvm_emul.S and include <linux/bug.h> in <asm/reg.h>
---
 arch/powerpc/include/asm/reg.h       |  5 +++++
 arch/powerpc/include/asm/reg_booke.h |  6 +++---
 arch/powerpc/kernel/head_32.h        |  4 ++++
 arch/powerpc/kernel/kvm_emul.S       | 13 +++++++++++++
 arch/powerpc/kernel/process.c        |  2 +-
 arch/powerpc/lib/sstep.c             |  2 +-
 6 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index be85cf156a1f..b270b570fb51 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -109,7 +109,12 @@
 #ifndef MSR_PMM
 #define MSR_PMM		__MASK(MSR_PMM_LG)	/* Performance monitor */
 #endif
+#if !defined(CONFIG_BOOKE) && !defined(CONFIG_40x)
 #define MSR_RI		__MASK(MSR_RI_LG)	/* Recoverable Exception */
+#elif !defined(__ASSEMBLY__)
+#include <linux/bug.h>
+#define MSR_RI		({BUILD_BUG(); 0; })
+#endif
 #define MSR_LE		__MASK(MSR_LE_LG)	/* Little Endian */
 
 #define MSR_TM		__MASK(MSR_TM_LG)	/* Transactional Mem Available */
diff --git a/arch/powerpc/include/asm/reg_booke.h b/arch/powerpc/include/asm/reg_booke.h
index 17b8dcd9a40d..6f40a8420ad0 100644
--- a/arch/powerpc/include/asm/reg_booke.h
+++ b/arch/powerpc/include/asm/reg_booke.h
@@ -38,15 +38,15 @@
 #if defined(CONFIG_PPC_BOOK3E_64)
 #define MSR_64BIT	MSR_CM
 
-#define MSR_		(MSR_ME | MSR_RI | MSR_CE)
+#define MSR_		(MSR_ME | MSR_CE)
 #define MSR_KERNEL	(MSR_ | MSR_64BIT)
 #define MSR_USER32	(MSR_ | MSR_PR | MSR_EE)
 #define MSR_USER64	(MSR_USER32 | MSR_64BIT)
 #elif defined (CONFIG_40x)
-#define MSR_KERNEL	(MSR_ME|MSR_RI|MSR_IR|MSR_DR|MSR_CE)
+#define MSR_KERNEL	(MSR_ME|MSR_IR|MSR_DR|MSR_CE)
 #define MSR_USER	(MSR_KERNEL|MSR_PR|MSR_EE)
 #else
-#define MSR_KERNEL	(MSR_ME|MSR_RI|MSR_CE)
+#define MSR_KERNEL	(MSR_ME|MSR_CE)
 #define MSR_USER	(MSR_KERNEL|MSR_PR|MSR_EE)
 #endif
 
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 6b1ec9e3541b..6c5f4183dc8e 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -63,7 +63,11 @@
 	mtspr	SPRN_DAR, r11	/* Tag DAR, to be used in DTLB Error */
 	.endif
 #endif
+#ifdef CONFIG_40x
+	LOAD_REG_IMMEDIATE(r11, MSR_KERNEL) /* re-enable MMU */
+#else
 	LOAD_REG_IMMEDIATE(r11, MSR_KERNEL & ~MSR_RI) /* re-enable MMU */
+#endif
 	mtspr	SPRN_SRR1, r11
 	lis	r11, 1f@h
 	ori	r11, r11, 1f@l
diff --git a/arch/powerpc/kernel/kvm_emul.S b/arch/powerpc/kernel/kvm_emul.S
index 7af6f8b50c5d..6a8073c2082b 100644
--- a/arch/powerpc/kernel/kvm_emul.S
+++ b/arch/powerpc/kernel/kvm_emul.S
@@ -56,14 +56,23 @@ kvm_emulate_mtmsrd:
 
 	/* Put MSR & ~(MSR_EE|MSR_RI) in r31 */
 	LL64(r31, KVM_MAGIC_PAGE + KVM_MAGIC_MSR, 0)
+#if !defined(CONFIG_BOOKE) && !defined(CONFIG_40x)
 	lis	r30, (~(MSR_EE | MSR_RI))@h
 	ori	r30, r30, (~(MSR_EE | MSR_RI))@l
+#else
+	lis	r30, (~MSR_EE)@h
+	ori	r30, r30, (~MSR_EE)@l
+#endif
 	and	r31, r31, r30
 
 	/* OR the register's (MSR_EE|MSR_RI) on MSR */
 kvm_emulate_mtmsrd_reg:
 	ori	r30, r0, 0
+#if !defined(CONFIG_BOOKE) && !defined(CONFIG_40x)
 	andi.	r30, r30, (MSR_EE|MSR_RI)
+#else
+	andi.	r30, r30, (MSR_EE)
+#endif
 	or	r31, r31, r30
 
 	/* Put MSR back into magic page */
@@ -112,7 +121,11 @@ kvm_emulate_mtmsrd_len:
 	.long (kvm_emulate_mtmsrd_end - kvm_emulate_mtmsrd) / 4
 
 
+#if !defined(CONFIG_BOOKE) && !defined(CONFIG_40x)
 #define MSR_SAFE_BITS (MSR_EE | MSR_RI)
+#else
+#define MSR_SAFE_BITS (MSR_EE)
+#endif
 #define MSR_CRITICAL_BITS ~MSR_SAFE_BITS
 
 .global kvm_emulate_mtmsr
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 185beb290580..5ba72e31de28 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1420,7 +1420,7 @@ static struct regbit msr_bits[] = {
 	{MSR_IR,	"IR"},
 	{MSR_DR,	"DR"},
 	{MSR_PMM,	"PMM"},
-#ifndef CONFIG_BOOKE
+#if !defined(CONFIG_BOOKE) && !defined(CONFIG_40x)
 	{MSR_RI,	"RI"},
 	{MSR_LE,	"LE"},
 #endif
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index d8d5f901cee1..357cc1fb4f67 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -3559,7 +3559,7 @@ int emulate_step(struct pt_regs *regs, struct ppc_inst instr)
 
 	case MTMSR:
 		val = regs->gpr[op.reg];
-		if ((val & MSR_RI) == 0)
+		if (cpu_has_msr_ri() && (val & MSR_RI) == 0)
 			/* can't step mtmsr[d] that would clear MSR_RI */
 			return -1;
 		/* here op.val is the mask of bits to change */
-- 
2.25.0