KVM: PPC: Book3S HV: Add workaround for msgsync erratum on POWER9 DD1

Submitted by Nicholas Piggin on April 5, 2017, 6:41 a.m.

Details

Message ID 20170405164118.7c78fcf5@roar.ozlabs.ibm.com
State New
Headers show

Commit Message

Nicholas Piggin April 5, 2017, 6:41 a.m.
On Wed, 5 Apr 2017 16:26:11 +1000
Paul Mackerras <paulus@ozlabs.org> wrote:

> On POWER9 DD1 the msgsync instruction doesn't work correctly, but the
> new 'darn' (deliver a random number) instruction happens to do an
> equivalent function as a side effect.
> 
> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

Seems okay to me. I had this, btw (after your feedback) which
I'll try to merge for using msgsync in Linux. What do you think?

--
To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch hide | download patch | download mbox

diff --git a/arch/powerpc/include/asm/feature-fixups.h b/arch/powerpc/include/asm/feature-fixups.h
index ddf54f5bbdd1..6b8b28d22323 100644
--- a/arch/powerpc/include/asm/feature-fixups.h
+++ b/arch/powerpc/include/asm/feature-fixups.h
@@ -66,7 +66,14 @@  label##5:							\
 #define END_FTR_SECTION(msk, val)		\
 	END_FTR_SECTION_NESTED(msk, val, 97)
 
+#define END_FTR_SECTION_NESTED_IFSET(msk, label) \
+	END_FTR_SECTION_NESTED((msk), (msk), label)
+
 #define END_FTR_SECTION_IFSET(msk)	END_FTR_SECTION((msk), (msk))
+
+#define END_FTR_SECTION_NESTED_IFCLR(msk, label) \
+	END_FTR_SECTION_NESTED((msk), 0, label)
+
 #define END_FTR_SECTION_IFCLR(msk)	END_FTR_SECTION((msk), 0)
 
 /* CPU feature sections with alternatives, use BEGIN_FTR_SECTION to start */
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index e7d6d86563ee..44009dfeab69 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -134,6 +134,7 @@ 
 #define PPC_INST_COPY			0x7c00060c
 #define PPC_INST_COPY_FIRST		0x7c20060c
 #define PPC_INST_CP_ABORT		0x7c00068c
+#define PPC_INST_DARN			0x7c0005e6
 #define PPC_INST_DCBA			0x7c0005ec
 #define PPC_INST_DCBA_MASK		0xfc0007fe
 #define PPC_INST_DCBAL			0x7c2005ec
@@ -161,6 +162,7 @@ 
 #define PPC_INST_MFTMR			0x7c0002dc
 #define PPC_INST_MSGSND			0x7c00019c
 #define PPC_INST_MSGCLR			0x7c0001dc
+#define PPC_INST_MSGSYNC		0x7c0006ec
 #define PPC_INST_MSGSNDP		0x7c00011c
 #define PPC_INST_MTTMR			0x7c0003dc
 #define PPC_INST_NOP			0x60000000
@@ -310,6 +312,7 @@ 
 #define __PPC_XS(s)	((((s) & 0x1f) << 21) | (((s) & 0x20) >> 5))
 #define __PPC_XT(s)	__PPC_XS(s)
 #define __PPC_T_TLB(t)	(((t) & 0x3) << 21)
+#define __PPC_L_DARN(l)	(((l) & 0x3) << 16)
 #define __PPC_WC(w)	(((w) & 0x3) << 21)
 #define __PPC_WS(w)	(((w) & 0x1f) << 11)
 #define __PPC_SH(s)	__PPC_WS(s)
@@ -333,6 +336,8 @@ 
 
 /* Deal with instructions that older assemblers aren't aware of */
 #define	PPC_CP_ABORT		stringify_in_c(.long PPC_INST_CP_ABORT)
+#define	PPC_DARN(t, l)		stringify_in_c(.long PPC_INST_DARN | \
+					___PPC_RT(t) | __PPC_L_DARN(l))
 #define	PPC_DCBAL(a, b)		stringify_in_c(.long PPC_INST_DCBAL | \
 					__PPC_RA(a) | __PPC_RB(b))
 #define	PPC_DCBZL(a, b)		stringify_in_c(.long PPC_INST_DCBZL | \
@@ -345,6 +350,7 @@ 
 					___PPC_RB(b) | __PPC_EH(eh))
 #define PPC_MSGSND(b)		stringify_in_c(.long PPC_INST_MSGSND | \
 					___PPC_RB(b))
+#define PPC_MSGSYNC		stringify_in_c(.long PPC_INST_MSGSYNC)
 #define PPC_MSGCLR(b)		stringify_in_c(.long PPC_INST_MSGCLR | \
 					___PPC_RB(b))
 #define PPC_MSGSNDP(b)		stringify_in_c(.long PPC_INST_MSGSNDP | \
diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index 359c44341761..00576c10fe6c 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -402,6 +402,19 @@  END_FTR_SECTION_IFCLR(CPU_FTR_601)
 	FTR_SECTION_ELSE_NESTED(848);	\
 	mtocrf (FXM), RS;		\
 	ALT_FTR_SECTION_END_NESTED_IFCLR(CPU_FTR_NOEXECUTE, 848)
+
+#define MSGSYNC(reg)			\
+	BEGIN_FTR_SECTION_NESTED(849);	\
+					\
+	BEGIN_FTR_SECTION_NESTED(850);	\
+	PPC_MSGSYNC;			\
+	lwsync;				\
+	FTR_SECTION_ELSE_NESTED(850);	\
+	PPC_DARN(reg, 2);		\
+	lwsync;				\
+	ALT_FTR_SECTION_END_NESTED_IFCLR(CPU_FTR_POWER9_DD1, 850); \
+					\
+	END_FTR_SECTION_NESTED_IFSET(CPU_FTR_HVMODE|CPU_FTR_ARCH_300, 849)
 #endif
 
 /*
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 7c6477d1840a..f8cf7b6a2aaa 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1239,6 +1239,7 @@  END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	/* Hypervisor doorbell - exit only if host IPI flag set */
 	cmpwi	r12, BOOK3S_INTERRUPT_H_DOORBELL
 	bne	3f
+	MSGSYNC(0)
 	lbz	r0, HSTATE_HOST_IPI(r13)
 	cmpwi	r0, 0
 	beq	4f