powerpc: Add support for POWER8 directed doorbell interrupts

powerpc: Add support for POWER8 directed doorbell interrupts

[Ian Munsie]

This patch series adds support for using directed doorbell interrupts for IPIs
between threads within a core, which is supported by POWER8.

This should avoid the overhead of using XICS to deliver an IPI within a core,
though delivering IPIs between threads of different cores must still use XICS
as before.

Please note that this series depends on this series posted by Michael Neuling,
as it adds additional relocation on exception vectors:
https://lists.ozlabs.org/pipermail/linuxppc-dev/2012-November/101910.html

[PATCH 1/7] powerpc: Define differences between doorbells on book3e and book3s

[Ian Munsie]

From: Ian Munsie <imunsie@au1.ibm.com>

There are a few key differences between doorbells on server compared
with embedded that we care about on Linux, namely:

- We have a new msgsndp instruction for directed privileged doorbells.
  msgsnd is used for directed hypervisor doorbells.
- The tag we use in the instruction is the Thread Identification
  Register of the recipient thread (since server doorbells can only
  occur between threads within a single core), and is only 7 bits wide.
- A new message type is introduced for server doorbells (none of the
  existing book3e message types are currently supported on book3s).

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
---
 arch/powerpc/include/asm/dbell.h      |   15 +++++++++++++++
 arch/powerpc/include/asm/ppc-opcode.h |    3 +++
 arch/powerpc/include/asm/reg.h        |    1 +
 arch/powerpc/kernel/dbell.c           |    4 ++--
 4 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/dbell.h b/arch/powerpc/include/asm/dbell.h
index 607e4ee..3b33856 100644
--- a/arch/powerpc/include/asm/dbell.h
+++ b/arch/powerpc/include/asm/dbell.h
@@ -28,8 +28,23 @@ enum ppc_dbell {
 	PPC_G_DBELL = 2,	/* guest doorbell */
 	PPC_G_DBELL_CRIT = 3,	/* guest critical doorbell */
 	PPC_G_DBELL_MC = 4,	/* guest mcheck doorbell */
+	PPC_DBELL_SERVER = 5,	/* doorbell on server */
 };
 
+#ifdef CONFIG_PPC_BOOK3S
+
+#define PPC_DBELL_MSGTYPE		PPC_DBELL_SERVER
+#define SPRN_DOORBELL_CPUTAG		SPRN_TIR
+#define PPC_DBELL_TAG_MASK		0x7f
+
+#else /* CONFIG_PPC_BOOK3S */
+
+#define PPC_DBELL_MSGTYPE		PPC_DBELL
+#define SPRN_DOORBELL_CPUTAG		SPRN_PIR
+#define PPC_DBELL_TAG_MASK		0x3fff
+
+#endif /* CONFIG_PPC_BOOK3S */
+
 extern void doorbell_cause_ipi(int cpu, unsigned long data);
 extern void doorbell_exception(struct pt_regs *regs);
 extern void doorbell_setup_this_cpu(void);
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index e434d8b..45fd394 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -100,6 +100,7 @@
 #define PPC_INST_MFSPR_PVR		0x7c1f42a6
 #define PPC_INST_MFSPR_PVR_MASK		0xfc1fffff
 #define PPC_INST_MSGSND			0x7c00019c
+#define PPC_INST_MSGSNDP		0x7c00011c
 #define PPC_INST_NOP			0x60000000
 #define PPC_INST_POPCNTB		0x7c0000f4
 #define PPC_INST_POPCNTB_MASK		0xfc0007fe
@@ -224,6 +225,8 @@
 					___PPC_RB(b) | __PPC_EH(eh))
 #define PPC_MSGSND(b)		stringify_in_c(.long PPC_INST_MSGSND | \
 					___PPC_RB(b))
+#define PPC_MSGSNDP(b)		stringify_in_c(.long PPC_INST_MSGSNDP | \
+					___PPC_RB(b))
 #define PPC_POPCNTB(a, s)	stringify_in_c(.long PPC_INST_POPCNTB | \
 					__PPC_RA(a) | __PPC_RS(s))
 #define PPC_POPCNTD(a, s)	stringify_in_c(.long PPC_INST_POPCNTD | \
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 1b853f7..736c6af 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -483,6 +483,7 @@
 #ifndef SPRN_PIR
 #define SPRN_PIR	0x3FF	/* Processor Identification Register */
 #endif
+#define SPRN_TIR	0x1BE	/* Thread Identification Register */
 #define SPRN_PTEHI	0x3D5	/* 981 7450 PTE HI word (S/W TLB load) */
 #define SPRN_PTELO	0x3D6	/* 982 7450 PTE LO word (S/W TLB load) */
 #define SPRN_PURR	0x135	/* Processor Utilization of Resources Reg */
diff --git a/arch/powerpc/kernel/dbell.c b/arch/powerpc/kernel/dbell.c
index a892680..9ebbc24 100644
--- a/arch/powerpc/kernel/dbell.c
+++ b/arch/powerpc/kernel/dbell.c
@@ -21,7 +21,7 @@
 #ifdef CONFIG_SMP
 void doorbell_setup_this_cpu(void)
 {
-	unsigned long tag = mfspr(SPRN_PIR) & 0x3fff;
+	unsigned long tag = mfspr(SPRN_DOORBELL_CPUTAG) & PPC_DBELL_TAG_MASK;
 
 	smp_muxed_ipi_set_data(smp_processor_id(), tag);
 }
@@ -30,7 +30,7 @@ void doorbell_cause_ipi(int cpu, unsigned long data)
 {
 	/* Order previous accesses vs. msgsnd, which is treated as a store */
 	mb();
-	ppc_msgsnd(PPC_DBELL, 0, data);
+	ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, data);
 }
 
 void doorbell_exception(struct pt_regs *regs)
-- 
1.7.10.4

[PATCH 2/7] powerpc: Add book3s hypervisor doorbell exception vectors

[Ian Munsie]

From: Ian Munsie <imunsie@au1.ibm.com>

Directed Hypervisor Doorbell Interrupts come in at 0xe80 (or
0xc000000000004e80 if relocation on exceptions is enabled), so add
exception vectors at these locations.

If doorbell support is not compiled in we handle it as an
unknown_exception.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
---
 arch/powerpc/include/asm/exception-64s.h |    2 ++
 arch/powerpc/kernel/exceptions-64s.S     |   16 +++++++++++++---
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index ad708dd..9d5367e 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -305,6 +305,8 @@ label##_relon_hv:					\
 #define SOFTEN_VALUE_0x502	PACA_IRQ_EE
 #define SOFTEN_VALUE_0x900	PACA_IRQ_DEC
 #define SOFTEN_VALUE_0x982	PACA_IRQ_DEC
+#define SOFTEN_VALUE_0xe80	PACA_IRQ_DBELL
+#define SOFTEN_VALUE_0xe82	PACA_IRQ_DBELL
 
 #define __SOFTEN_TEST(h, vec)						\
 	lbz	r10,PACASOFTIRQEN(r13);					\
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 4665e82..d08a3cd 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -293,6 +293,8 @@ hv_exception_trampoline:
 	b	hmi_exception_hv
 	. = 0xe60
 	b	hmi_exception_hv
+	. = 0xe80
+	b	h_doorbell_hv
 
 	/* We need to deal with the Altivec unavailable exception
 	 * here which is at 0xf20, thus in the middle of the
@@ -514,6 +516,8 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_206)
 	KVM_HANDLER(PACA_EXGEN, EXC_HV, 0xe42)
 	STD_EXCEPTION_HV(., 0xe62, hmi_exception) /* need to flush cache ? */
 	KVM_HANDLER(PACA_EXGEN, EXC_HV, 0xe62)
+	MASKABLE_EXCEPTION_HV(., 0xe82, h_doorbell)
+	KVM_HANDLER(PACA_EXGEN, EXC_HV, 0xe82)
 
 	/* moved from 0xf00 */
 	STD_EXCEPTION_PSERIES(., 0xf00, performance_monitor)
@@ -657,6 +661,11 @@ machine_check_common:
 	STD_EXCEPTION_COMMON(0xe00, trap_0e, .unknown_exception)
 	STD_EXCEPTION_COMMON(0xe40, emulation_assist, .program_check_exception)
 	STD_EXCEPTION_COMMON(0xe60, hmi_exception, .unknown_exception)
+#ifdef CONFIG_PPC_DOORBELL
+	STD_EXCEPTION_COMMON_ASYNC(0xe80, h_doorbell, .doorbell_exception)
+#else
+	STD_EXCEPTION_COMMON_ASYNC(0xe80, h_doorbell, .unknown_exception)
+#endif
 	STD_EXCEPTION_COMMON_ASYNC(0xf00, performance_monitor, .performance_monitor_exception)
 	STD_EXCEPTION_COMMON(0x1300, instruction_breakpoint, .instruction_breakpoint_exception)
 	STD_EXCEPTION_COMMON(0x1502, denorm, .unknown_exception)
@@ -773,9 +782,8 @@ system_call_relon_pSeries:
 	. = 0x4e60
 	b	hmi_exception_relon_hv
 
-	/* For when we support the doorbell interrupt:
-	STD_RELON_EXCEPTION_HYPERVISOR(0x4e80, 0xe80, doorbell_hyper)
-	*/
+	. = 0x4e80
+	b	h_doorbell_relon_hv
 
 performance_monitor_relon_pSeries_1:
 	. = 0x4f00
@@ -1355,6 +1363,8 @@ _GLOBAL(do_stab_bolted)
 	KVM_HANDLER(PACA_EXGEN, EXC_HV, 0xe40)
 	STD_RELON_EXCEPTION_HV(., 0xe60, hmi_exception)
 	KVM_HANDLER(PACA_EXGEN, EXC_HV, 0xe60)
+	MASKABLE_RELON_EXCEPTION_HV(., 0xe80, h_doorbell)
+	KVM_HANDLER(PACA_EXGEN, EXC_HV, 0xe80)
 
 	STD_RELON_EXCEPTION_PSERIES(., 0xf00, performance_monitor)
 	STD_RELON_EXCEPTION_PSERIES(., 0xf20, altivec_unavailable)
-- 
1.7.10.4

[PATCH 3/7] powerpc: Add book3s privileged doorbell exception vectors

[Ian Munsie]

From: Ian Munsie <imunsie@au1.ibm.com>

Directed Privileged Doorbell Interrupts come in at 0xa00 (or
0xc000000000004a00 if relocation on exception is enabled), so add
exception vectors at these locations.

If doorbell support is not compiled in we handle it as an
unknown_exception.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
---
 arch/powerpc/include/asm/exception-64s.h |    1 +
 arch/powerpc/kernel/exceptions-64s.S     |    9 +++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 9d5367e..b1edd80 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -305,6 +305,7 @@ label##_relon_hv:					\
 #define SOFTEN_VALUE_0x502	PACA_IRQ_EE
 #define SOFTEN_VALUE_0x900	PACA_IRQ_DEC
 #define SOFTEN_VALUE_0x982	PACA_IRQ_DEC
+#define SOFTEN_VALUE_0xa00	PACA_IRQ_DBELL
 #define SOFTEN_VALUE_0xe80	PACA_IRQ_DBELL
 #define SOFTEN_VALUE_0xe82	PACA_IRQ_DBELL
 
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index d08a3cd..176bf99 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -252,7 +252,7 @@ hardware_interrupt_hv:
 	MASKABLE_EXCEPTION_PSERIES(0x900, 0x900, decrementer)
 	STD_EXCEPTION_HV(0x980, 0x982, hdecrementer)
 
-	STD_EXCEPTION_PSERIES(0xa00, 0xa00, trap_0a)
+	MASKABLE_EXCEPTION_PSERIES(0xa00, 0xa00, doorbell_super)
 	KVM_HANDLER_PR(PACA_EXGEN, EXC_STD, 0xa00)
 
 	STD_EXCEPTION_PSERIES(0xb00, 0xb00, trap_0b)
@@ -655,7 +655,11 @@ machine_check_common:
 	STD_EXCEPTION_COMMON_ASYNC(0x500, hardware_interrupt, do_IRQ)
 	STD_EXCEPTION_COMMON_ASYNC(0x900, decrementer, .timer_interrupt)
 	STD_EXCEPTION_COMMON(0x980, hdecrementer, .hdec_interrupt)
-	STD_EXCEPTION_COMMON(0xa00, trap_0a, .unknown_exception)
+#ifdef CONFIG_PPC_DOORBELL
+	STD_EXCEPTION_COMMON_ASYNC(0xa00, doorbell_super, .doorbell_exception)
+#else
+	STD_EXCEPTION_COMMON_ASYNC(0xa00, doorbell_super, .unknown_exception)
+#endif
 	STD_EXCEPTION_COMMON(0xb00, trap_0b, .unknown_exception)
 	STD_EXCEPTION_COMMON(0xd00, single_step, .single_step_exception)
 	STD_EXCEPTION_COMMON(0xe00, trap_0e, .unknown_exception)
@@ -755,6 +759,7 @@ hardware_interrupt_relon_hv:
 	STD_RELON_EXCEPTION_PSERIES(0x4800, 0x800, fp_unavailable)
 	MASKABLE_RELON_EXCEPTION_PSERIES(0x4900, 0x900, decrementer)
 	STD_RELON_EXCEPTION_HV(0x4980, 0x982, hdecrementer)
+	MASKABLE_RELON_EXCEPTION_PSERIES(0x4a00, 0xa00, doorbell_super)
 	STD_RELON_EXCEPTION_PSERIES(0x4b00, 0xb00, trap_0b)
 
 	. = 0x4c00
-- 
1.7.10.4

[PATCH 4/7] powerpc: Select either privileged or hypervisor doorbell when sending

[Ian Munsie]

From: Ian Munsie <imunsie@au1.ibm.com>

On book3s we have two msgsnd instructions with differing privilege
levels. This patch selects the appropriate instruction to use whenever
we send a doorbell interrupt.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
---
 arch/powerpc/include/asm/dbell.h |   15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/dbell.h b/arch/powerpc/include/asm/dbell.h
index 3b33856..5fa6b20 100644
--- a/arch/powerpc/include/asm/dbell.h
+++ b/arch/powerpc/include/asm/dbell.h
@@ -37,12 +37,25 @@ enum ppc_dbell {
 #define SPRN_DOORBELL_CPUTAG		SPRN_TIR
 #define PPC_DBELL_TAG_MASK		0x7f
 
+static inline void _ppc_msgsnd(u32 msg)
+{
+	if (cpu_has_feature(CPU_FTR_HVMODE))
+		__asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
+	else
+		__asm__ __volatile__ (PPC_MSGSNDP(%0) : : "r" (msg));
+}
+
 #else /* CONFIG_PPC_BOOK3S */
 
 #define PPC_DBELL_MSGTYPE		PPC_DBELL
 #define SPRN_DOORBELL_CPUTAG		SPRN_PIR
 #define PPC_DBELL_TAG_MASK		0x3fff
 
+static inline void _ppc_msgsnd(u32 msg)
+{
+	__asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
+}
+
 #endif /* CONFIG_PPC_BOOK3S */
 
 extern void doorbell_cause_ipi(int cpu, unsigned long data);
@@ -54,7 +67,7 @@ static inline void ppc_msgsnd(enum ppc_dbell type, u32 flags, u32 tag)
 	u32 msg = PPC_DBELL_TYPE(type) | (flags & PPC_DBELL_MSG_BRDCAST) |
 			(tag & 0x07ffffff);
 
-	__asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
+	_ppc_msgsnd(msg);
 }
 
 #endif /* _ASM_POWERPC_DBELL_H */
-- 
1.7.10.4

[PATCH 5/7] powerpc: Add code to handle soft-disabled doorbells on server

[Ian Munsie]

From: Ian Munsie <imunsie@au1.ibm.com>

This patch adds the logic to properly handle doorbells that come in when
interrupts have been soft disabled and to replay them when interrupts
are re-enabled:

- masked_##_H##interrupt is modified to leave interrupts enabled when a
  doorbell has come in since doorbells are edge sensitive and as such
  won't be automatically re-raised.

- __check_irq_replay now tests if a doorbell happened on book3s, and
  returns either 0xe80 or 0xa00 depending on whether we are the
  hypervisor or not.

- restore_check_irq_replay now tests for the two possible server
  doorbell vector numbers to replay.

- __replay_interrupt also adds tests for the two server doorbell vector
  numbers, and is modified to use a compare instruction rather than an
  andi. on the single bit difference between 0x500 and 0x900.

The last two use a CPU feature section to avoid needlessly testing
against the hypervisor vector if it is not the hypervisor, and vice
versa.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
---
 arch/powerpc/kernel/entry_64.S       |   13 ++++++++++--
 arch/powerpc/kernel/exceptions-64s.S |   37 +++++++++++++++++++++++-----------
 arch/powerpc/kernel/irq.c            |   11 ++++++++--
 3 files changed, 45 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index ad76666..df6857f 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -842,13 +842,22 @@ restore_check_irq_replay:
 	addi	r3,r1,STACK_FRAME_OVERHEAD;
 	bl	.timer_interrupt
 	b	.ret_from_except
+#ifdef CONFIG_PPC_DOORBELL
+1:
 #ifdef CONFIG_PPC_BOOK3E
-1:	cmpwi	cr0,r3,0x280
+	cmpwi	cr0,r3,0x280
+#else
+	BEGIN_FTR_SECTION
+		cmpwi	cr0,r3,0xe80
+	FTR_SECTION_ELSE
+		cmpwi	cr0,r3,0xa00
+	ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
+#endif /* CONFIG_PPC_BOOK3E */
 	bne	1f
 	addi	r3,r1,STACK_FRAME_OVERHEAD;
 	bl	.doorbell_exception
 	b	.ret_from_except
-#endif /* CONFIG_PPC_BOOK3E */
+#endif /* CONFIG_PPC_DOORBELL */
 1:	b	.ret_from_except /* What else to do here ? */
  
 unrecov_restore:
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 176bf99..32fc04f 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -528,10 +528,12 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_206)
 	KVM_HANDLER_PR(PACA_EXGEN, EXC_STD, 0xf40)
 
 /*
- * An interrupt came in while soft-disabled. We set paca->irq_happened,
- * then, if it was a decrementer interrupt, we bump the dec to max and
- * and return, else we hard disable and return. This is called with
- * r10 containing the value to OR to the paca field.
+ * An interrupt came in while soft-disabled. We set paca->irq_happened, then:
+ * - If it was a decrementer interrupt, we bump the dec to max and and return.
+ * - If it was a doorbell we return immediately since doorbells are edge
+ *   triggered and won't automatically refire.
+ * - else we hard disable and return.
+ * This is called with r10 containing the value to OR to the paca field.
  */
 #define MASKED_INTERRUPT(_H)				\
 masked_##_H##interrupt:					\
@@ -539,13 +541,15 @@ masked_##_H##interrupt:					\
 	lbz	r11,PACAIRQHAPPENED(r13);		\
 	or	r11,r11,r10;				\
 	stb	r11,PACAIRQHAPPENED(r13);		\
-	andi.	r10,r10,PACA_IRQ_DEC;			\
-	beq	1f;					\
+	cmpwi	r10,PACA_IRQ_DEC;			\
+	bne	1f;					\
 	lis	r10,0x7fff;				\
 	ori	r10,r10,0xffff;				\
 	mtspr	SPRN_DEC,r10;				\
 	b	2f;					\
-1:	mfspr	r10,SPRN_##_H##SRR1;			\
+1:	cmpwi	r10,PACA_IRQ_DBELL;			\
+	beq	2f;					\
+	mfspr	r10,SPRN_##_H##SRR1;			\
 	rldicl	r10,r10,48,1; /* clear MSR_EE */	\
 	rotldi	r10,r10,16;				\
 	mtspr	SPRN_##_H##SRR1,r10;			\
@@ -562,8 +566,8 @@ masked_##_H##interrupt:					\
 
 /*
  * Called from arch_local_irq_enable when an interrupt needs
- * to be resent. r3 contains 0x500 or 0x900 to indicate which
- * kind of interrupt. MSR:EE is already off. We generate a
+ * to be resent. r3 contains 0x500, 0x900, 0xa00 or 0xe80 to indicate
+ * which kind of interrupt. MSR:EE is already off. We generate a
  * stackframe like if a real interrupt had happened.
  *
  * Note: While MSR:EE is off, we need to make sure that _MSR
@@ -579,9 +583,18 @@ _GLOBAL(__replay_interrupt)
 	mflr	r11
 	mfcr	r9
 	ori	r12,r12,MSR_EE
-	andi.	r3,r3,0x0800
-	bne	decrementer_common
-	b	hardware_interrupt_common
+	cmpwi	r3,0x900
+	beq	decrementer_common
+	cmpwi	r3,0x500
+	beq	hardware_interrupt_common
+BEGIN_FTR_SECTION
+	cmpwi	r3,0xe80
+	beq	h_doorbell_common
+FTR_SECTION_ELSE
+	cmpwi	r3,0xa00
+	beq	doorbell_super_common
+ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
+	blr
 
 #ifdef CONFIG_PPC_PSERIES
 /*
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 71413f4..4f97fe3 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -122,8 +122,8 @@ static inline notrace int decrementer_check_overflow(void)
 }
 
 /* This is called whenever we are re-enabling interrupts
- * and returns either 0 (nothing to do) or 500/900 if there's
- * either an EE or a DEC to generate.
+ * and returns either 0 (nothing to do) or 500/900/280/a00/e80 if
+ * there's an EE, DEC or DBELL to generate.
  *
  * This is called in two contexts: From arch_local_irq_restore()
  * before soft-enabling interrupts, and from the exception exit
@@ -182,6 +182,13 @@ notrace unsigned int __check_irq_replay(void)
 	local_paca->irq_happened &= ~PACA_IRQ_DBELL;
 	if (happened & PACA_IRQ_DBELL)
 		return 0x280;
+#else
+	local_paca->irq_happened &= ~PACA_IRQ_DBELL;
+	if (happened & PACA_IRQ_DBELL) {
+		if (cpu_has_feature(CPU_FTR_HVMODE))
+			return 0xe80;
+		return 0xa00;
+	}
 #endif /* CONFIG_PPC_BOOK3E */
 
 	/* There should be nothing left ! */
-- 
1.7.10.4

[PATCH 6/7] powerpc: Update Kconfig + Makefile to prepare for server doorbells

[Ian Munsie]

From: Ian Munsie <imunsie@au1.ibm.com>

Move the rule to build doorbell support out of the Makefile and into a
new Kconfig boolean that platforms can select.

We will add doorbell support to pseries as well in the next patch.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
---
 arch/powerpc/kernel/Makefile           |    4 ++--
 arch/powerpc/platforms/Kconfig.cputype |    6 ++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 8f61934..44fbbea 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -75,8 +75,8 @@ endif
 obj64-$(CONFIG_HIBERNATION)	+= swsusp_asm64.o
 obj-$(CONFIG_MODULES)		+= module.o module_$(CONFIG_WORD_SIZE).o
 obj-$(CONFIG_44x)		+= cpu_setup_44x.o
-obj-$(CONFIG_PPC_FSL_BOOK3E)	+= cpu_setup_fsl_booke.o dbell.o
-obj-$(CONFIG_PPC_BOOK3E_64)	+= dbell.o
+obj-$(CONFIG_PPC_FSL_BOOK3E)	+= cpu_setup_fsl_booke.o
+obj-$(CONFIG_PPC_DOORBELL)	+= dbell.o
 obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o
 
 extra-y				:= head_$(CONFIG_WORD_SIZE).o
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 72afd28..cea2f09 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -76,6 +76,7 @@ config PPC_BOOK3E_64
 	bool "Embedded processors"
 	select PPC_FPU # Make it a choice ?
 	select PPC_SMP_MUXED_IPI
+	select PPC_DOORBELL
 
 endchoice
 
@@ -208,6 +209,7 @@ config PPC_FSL_BOOK3E
 	select FSL_EMB_PERFMON
 	select PPC_SMP_MUXED_IPI
 	select SYS_SUPPORTS_HUGETLBFS if PHYS_64BIT || PPC64
+	select PPC_DOORBELL
 	default y if FSL_BOOKE
 
 config PTE_64BIT
@@ -382,4 +384,8 @@ config NOT_COHERENT_CACHE
 config CHECK_CACHE_COHERENCY
 	bool
 
+config PPC_DOORBELL
+	bool
+	default n
+
 endmenu
-- 
1.7.10.4

[PATCH 7/7] powerpc: Hook up doorbells on server

[Ian Munsie]

From: Ian Munsie <imunsie@au1.ibm.com>

This patch actually hooks up doorbell interrupts on POWER8:

- Select the PPC_DOORBELL Kconfig option from PPC_PSERIES

- Add the doorbell CPU feature bit to POWER8

- We define a new pSeries_cause_ipi_mux() function that issues a
  doorbell interrupt if the recipient is another thread within the same
  core as the sender. If the recipient is in a different core it falls
  back to using XICS to deliver the IPI as before.

- During pSeries_smp_probe() at boot, we check if doorbell interrupts
  are supported. If they are we set the cause_ipi function pointer to
  the above mentioned function, otherwise we leave it as whichever XICS
  cause_ipi function was determined by xics_smp_probe().

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
---
 arch/powerpc/include/asm/cputable.h    |    3 ++-
 arch/powerpc/platforms/pseries/Kconfig |    1 +
 arch/powerpc/platforms/pseries/smp.c   |   33 ++++++++++++++++++++++++++++++--
 3 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 76f81bd..fc4d2c5 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -408,7 +408,8 @@ extern const char *powerpc_base_platform;
 	    CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE | \
 	    CPU_FTR_DSCR | CPU_FTR_SAO  | \
 	    CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_POPCNTD | \
-	    CPU_FTR_ICSWX | CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY)
+	    CPU_FTR_ICSWX | CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
+	    CPU_FTR_DBELL)
 #define CPU_FTRS_CELL	(CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \
 	    CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \
 	    CPU_FTR_ALTIVEC_COMP | CPU_FTR_MMCRA | CPU_FTR_SMT | \
diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
index 837cf49..9a0941b 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -17,6 +17,7 @@ config PPC_PSERIES
 	select PPC_NATIVE
 	select PPC_PCI_CHOICE if EXPERT
 	select ZLIB_DEFLATE
+	select PPC_DOORBELL
 	default y
 
 config PPC_SPLPAR
diff --git a/arch/powerpc/platforms/pseries/smp.c b/arch/powerpc/platforms/pseries/smp.c
index 9fc0a49..32c82c2 100644
--- a/arch/powerpc/platforms/pseries/smp.c
+++ b/arch/powerpc/platforms/pseries/smp.c
@@ -42,6 +42,7 @@
 #include <asm/vdso_datapage.h>
 #include <asm/cputhreads.h>
 #include <asm/xics.h>
+#include <asm/dbell.h>
 
 #include "plpar_wrappers.h"
 #include "pseries.h"
@@ -54,6 +55,11 @@
  */
 static cpumask_var_t of_spin_mask;
 
+/*
+ * If we multiplex IPI mechanisms, store the appropriate XICS IPI mechanism here
+ */
+static void  (*xics_cause_ipi)(int cpu, unsigned long data);
+
 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
 int smp_query_cpu_stopped(unsigned int pcpu)
 {
@@ -137,6 +143,8 @@ static void __devinit smp_xics_setup_cpu(int cpu)
 {
 	if (cpu != boot_cpuid)
 		xics_setup_cpu();
+	if (cpu_has_feature(CPU_FTR_DBELL))
+		doorbell_setup_this_cpu();
 
 	if (firmware_has_feature(FW_FEATURE_SPLPAR))
 		vpa_init(cpu);
@@ -195,6 +203,27 @@ static int smp_pSeries_cpu_bootable(unsigned int nr)
 	return 1;
 }
 
+/* Only used on systems that support multiple IPI mechanisms */
+static void pSeries_cause_ipi_mux(int cpu, unsigned long data)
+{
+	if (cpumask_test_cpu(cpu, cpu_sibling_mask(smp_processor_id())))
+		doorbell_cause_ipi(cpu, data);
+	else
+		xics_cause_ipi(cpu, data);
+}
+
+static __init int pSeries_smp_probe(void)
+{
+	int ret = xics_smp_probe();
+
+	if (cpu_has_feature(CPU_FTR_DBELL)) {
+		xics_cause_ipi = smp_ops->cause_ipi;
+		smp_ops->cause_ipi = pSeries_cause_ipi_mux;
+	}
+
+	return ret;
+}
+
 static struct smp_ops_t pSeries_mpic_smp_ops = {
 	.message_pass	= smp_mpic_message_pass,
 	.probe		= smp_mpic_probe,
@@ -204,8 +233,8 @@ static struct smp_ops_t pSeries_mpic_smp_ops = {
 
 static struct smp_ops_t pSeries_xics_smp_ops = {
 	.message_pass	= NULL,	/* Use smp_muxed_ipi_message_pass */
-	.cause_ipi	= NULL,	/* Filled at runtime by xics_smp_probe() */
-	.probe		= xics_smp_probe,
+	.cause_ipi	= NULL,	/* Filled at runtime by pSeries_smp_probe() */
+	.probe		= pSeries_smp_probe,
 	.kick_cpu	= smp_pSeries_kick_cpu,
 	.setup_cpu	= smp_xics_setup_cpu,
 	.cpu_bootable	= smp_pSeries_cpu_bootable,
-- 
1.7.10.4