Patchwork powerpc: Add support for using doorbells for SMP IPI

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Submitter Kumar Gala
Date Feb. 12, 2009, 11:54 p.m.
Message ID <1234482893-17712-1-git-send-email-galak@kernel.crashing.org>
Download mbox | patch
Permalink /patch/23095/
State Accepted
Commit 620165f971753c2c451c880796bac7cd66f3534a
Delegated to: Benjamin Herrenschmidt
Headers show

Comments

Kumar Gala - Feb. 12, 2009, 11:54 p.m.
The e500mc supports the new msgsnd/doorbell mechanisms that were added in
the Power ISA 2.05 architecture.  We use the normal level doorbell for
doing SMP IPIs at this point.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
---
 arch/powerpc/include/asm/cputable.h  |    4 ++-
 arch/powerpc/include/asm/dbell.h     |   43 +++++++++++++++++++++++++++++++++
 arch/powerpc/kernel/Makefile         |    2 +-
 arch/powerpc/kernel/dbell.c          |   44 ++++++++++++++++++++++++++++++++++
 arch/powerpc/kernel/head_fsl_booke.S |    6 ++++-
 arch/powerpc/kernel/traps.c          |   21 ++++++++++++++++
 6 files changed, 117 insertions(+), 3 deletions(-)
 create mode 100644 arch/powerpc/include/asm/dbell.h
 create mode 100644 arch/powerpc/kernel/dbell.c
Benjamin Herrenschmidt - Feb. 13, 2009, 2:46 a.m.
On Thu, 2009-02-12 at 17:54 -0600, Kumar Gala wrote:
> The e500mc supports the new msgsnd/doorbell mechanisms that were added in
> the Power ISA 2.05 architecture.  We use the normal level doorbell for
> doing SMP IPIs at this point.
> 

Cool stuff. Haven't reviewed in details yet tho :-) But I was
thinking...

We should introduce a special xmon variant of local_irq_save/restore for
use by xmon that masks MSR:CE and use a crit doorbell for xmon IPI, that
would increase significantly the ability of xmon to catch deadlocked
CPUs, and we could use external CRITs as a more generic way of doing
IPIs, no ?

In fact, we should expose a local_crit_irq_save/restore (disable/enable)
too for things like watchdog drivers etc... which may want to use these.

Cheers,
Ben.
Kumar Gala - Feb. 13, 2009, 5:10 a.m.
On Feb 12, 2009, at 8:46 PM, Benjamin Herrenschmidt wrote:

> On Thu, 2009-02-12 at 17:54 -0600, Kumar Gala wrote:
>> The e500mc supports the new msgsnd/doorbell mechanisms that were  
>> added in
>> the Power ISA 2.05 architecture.  We use the normal level doorbell  
>> for
>> doing SMP IPIs at this point.
>>
>
> Cool stuff. Haven't reviewed in details yet tho :-) But I was
> thinking...
>
> We should introduce a special xmon variant of local_irq_save/restore  
> for
> use by xmon that masks MSR:CE and use a crit doorbell for xmon IPI,  
> that
> would increase significantly the ability of xmon to catch deadlocked
> CPUs, and we could use external CRITs as a more generic way of doing
> IPIs, no ?

crit doorbell for xmon IPI sounds interesting.  However, I don't  
following about use of external CRITs for IPIs.

> In fact, we should expose a local_crit_irq_save/restore (disable/ 
> enable)
> too for things like watchdog drivers etc... which may want to use  
> these.

Yeah, probably a good thing for us to add.

- k
Benjamin Herrenschmidt - Feb. 13, 2009, 5:25 a.m.
> crit doorbell for xmon IPI sounds interesting.  However, I don't  
> following about use of external CRITs for IPIs.

Just a finger not following the brain :-) I meant for NMI's

Cheers,
Ben.
Benjamin Herrenschmidt - Feb. 23, 2009, 2:43 a.m.
On Thu, 2009-02-12 at 17:54 -0600, Kumar Gala wrote:
> The e500mc supports the new msgsnd/doorbell mechanisms that were added in
> the Power ISA 2.05 architecture.  We use the normal level doorbell for
> doing SMP IPIs at this point.

Any reason why you don't use the tag ? I'm not too familiar with the
doorbell stuff just yet but can't you use that instead of doing those
atomics ?

On thing we also need to look at is change our low level msg send to
take a CPU mask.

This will be better generically and we need a good cpu mask based IPI
for the TLB stuff anyway. Volunteer ? :-)

Cheers,
Ben.

> Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
> ---
>  arch/powerpc/include/asm/cputable.h  |    4 ++-
>  arch/powerpc/include/asm/dbell.h     |   43 +++++++++++++++++++++++++++++++++
>  arch/powerpc/kernel/Makefile         |    2 +-
>  arch/powerpc/kernel/dbell.c          |   44 ++++++++++++++++++++++++++++++++++
>  arch/powerpc/kernel/head_fsl_booke.S |    6 ++++-
>  arch/powerpc/kernel/traps.c          |   21 ++++++++++++++++
>  6 files changed, 117 insertions(+), 3 deletions(-)
>  create mode 100644 arch/powerpc/include/asm/dbell.h
>  create mode 100644 arch/powerpc/kernel/dbell.c
> 
> diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
> index 4911104..fca1611 100644
> --- a/arch/powerpc/include/asm/cputable.h
> +++ b/arch/powerpc/include/asm/cputable.h
> @@ -145,6 +145,7 @@ extern const char *powerpc_base_platform;
>  #define CPU_FTR_USE_TB			ASM_CONST(0x0000000000000040)
>  #define CPU_FTR_L2CSR			ASM_CONST(0x0000000000000080)
>  #define CPU_FTR_601			ASM_CONST(0x0000000000000100)
> +#define CPU_FTR_DBELL			ASM_CONST(0x0000000000000200)
>  #define CPU_FTR_CAN_NAP			ASM_CONST(0x0000000000000400)
>  #define CPU_FTR_L3CR			ASM_CONST(0x0000000000000800)
>  #define CPU_FTR_L3_DISABLE_NAP		ASM_CONST(0x0000000000001000)
> @@ -373,7 +374,8 @@ extern const char *powerpc_base_platform;
>  	    CPU_FTR_NODSISRALIGN | CPU_FTR_NOEXECUTE)
>  #define CPU_FTRS_E500MC	(CPU_FTR_MAYBE_CAN_DOZE | CPU_FTR_USE_TB | \
>  	    CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_NODSISRALIGN | \
> -	    CPU_FTR_L2CSR | CPU_FTR_LWSYNC | CPU_FTR_NOEXECUTE)
> +	    CPU_FTR_L2CSR | CPU_FTR_LWSYNC | CPU_FTR_NOEXECUTE | \
> +	    CPU_FTR_DBELL)
>  #define CPU_FTRS_GENERIC_32	(CPU_FTR_COMMON | CPU_FTR_NODSISRALIGN)
>  
>  /* 64-bit CPUs */
> diff --git a/arch/powerpc/include/asm/dbell.h b/arch/powerpc/include/asm/dbell.h
> new file mode 100644
> index 0000000..501189a
> --- /dev/null
> +++ b/arch/powerpc/include/asm/dbell.h
> @@ -0,0 +1,43 @@
> +/*
> + * Copyright 2009 Freescale Semicondutor, Inc.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + *
> + * provides masks and opcode images for use by code generation, emulation
> + * and for instructions that older assemblers might not know about
> + */
> +#ifndef _ASM_POWERPC_DBELL_H
> +#define _ASM_POWERPC_DBELL_H
> +
> +#include <linux/smp.h>
> +#include <linux/threads.h>
> +
> +#include <asm/ppc-opcode.h>
> +
> +#define PPC_DBELL_MSG_BRDCAST	(0x04000000)
> +#define PPC_DBELL_TYPE(x)	(((x) & 0xf) << 28)
> +enum ppc_dbell {
> +	PPC_DBELL = 0,		/* doorbell */
> +	PPC_DBELL_CRIT = 1,	/* critical doorbell */
> +	PPC_G_DBELL = 2,	/* guest doorbell */
> +	PPC_G_DBELL_CRIT = 3,	/* guest critical doorbell */
> +	PPC_G_DBELL_MC = 4,	/* guest mcheck doorbell */
> +};
> +
> +#ifdef CONFIG_SMP
> +extern unsigned long dbell_smp_message[NR_CPUS];
> +extern void smp_dbell_message_pass(int target, int msg);
> +#endif
> +
> +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));
> +}
> +
> +#endif /* _ASM_POWERPC_DBELL_H */
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index d159921..f420844 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -61,7 +61,7 @@ obj-$(CONFIG_HIBERNATION)	+= swsusp.o suspend.o \
>  obj64-$(CONFIG_HIBERNATION)	+= swsusp_asm64.o
>  obj-$(CONFIG_MODULES)		+= module.o module_$(CONFIG_WORD_SIZE).o
>  obj-$(CONFIG_44x)		+= cpu_setup_44x.o
> -obj-$(CONFIG_FSL_BOOKE)		+= cpu_setup_fsl_booke.o
> +obj-$(CONFIG_FSL_BOOKE)		+= cpu_setup_fsl_booke.o dbell.o
>  
>  extra-$(CONFIG_PPC_STD_MMU)	:= head_32.o
>  extra-$(CONFIG_PPC64)		:= head_64.o
> diff --git a/arch/powerpc/kernel/dbell.c b/arch/powerpc/kernel/dbell.c
> new file mode 100644
> index 0000000..1493734
> --- /dev/null
> +++ b/arch/powerpc/kernel/dbell.c
> @@ -0,0 +1,44 @@
> +/*
> + * Author: Kumar Gala <galak@kernel.crashing.org>
> + *
> + * Copyright 2009 Freescale Semiconductor Inc.
> + *
> + * This program is free software; you can redistribute  it and/or modify it
> + * under  the terms of  the GNU General  Public License as published by the
> + * Free Software Foundation;  either version 2 of the  License, or (at your
> + * option) any later version.
> + */
> +
> +#include <linux/stddef.h>
> +#include <linux/kernel.h>
> +#include <linux/smp.h>
> +#include <linux/threads.h>
> +
> +#include <asm/dbell.h>
> +
> +#ifdef CONFIG_SMP
> +unsigned long dbell_smp_message[NR_CPUS];
> +
> +void smp_dbell_message_pass(int target, int msg)
> +{
> +	int i;
> +
> +	if(target < NR_CPUS) {
> +		set_bit(msg, &dbell_smp_message[target]);
> +		ppc_msgsnd(PPC_DBELL, 0, target);
> +	}
> +	else if(target == MSG_ALL_BUT_SELF) {
> +		for_each_online_cpu(i) {
> +			if (i == smp_processor_id())
> +				continue;
> +			set_bit(msg, &dbell_smp_message[i]);
> +			ppc_msgsnd(PPC_DBELL, 0, i);
> +		}
> +	}
> +	else { /* target == MSG_ALL */
> +		for_each_online_cpu(i)
> +			set_bit(msg, &dbell_smp_message[i]);
> +		ppc_msgsnd(PPC_DBELL, PPC_DBELL_MSG_BRDCAST, 0);
> +	}
> +}
> +#endif
> diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
> index 4ea6e1a..4c22620 100644
> --- a/arch/powerpc/kernel/head_fsl_booke.S
> +++ b/arch/powerpc/kernel/head_fsl_booke.S
> @@ -698,7 +698,9 @@ interrupt_base:
>  	/* Performance Monitor */
>  	EXCEPTION(0x2060, PerformanceMonitor, performance_monitor_exception, EXC_XFER_STD)
>  
> -	EXCEPTION(0x2070, Doorbell, unknown_exception, EXC_XFER_STD)
> +	EXCEPTION(0x2070, Doorbell, doorbell_exception, EXC_XFER_STD)
> +
> +	CRITICAL_EXCEPTION(0x2080, CriticalDoorbell, unknown_exception)
>  
>  	/* Debug Interrupt */
>  	DEBUG_DEBUG_EXCEPTION
> @@ -921,6 +923,8 @@ _GLOBAL(__setup_e500mc_ivors)
>  	mtspr	SPRN_IVOR35,r3
>  	li	r3,Doorbell@l
>  	mtspr	SPRN_IVOR36,r3
> +	li	r3,CriticalDoorbell@l
> +	mtspr	SPRN_IVOR37,r3
>  	sync
>  	blr
>  
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index 970d66e..678fbff 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -53,6 +53,9 @@
>  #endif
>  #include <asm/kexec.h>
>  #include <asm/ppc-opcode.h>
> +#ifdef CONFIG_FSL_BOOKE
> +#include <asm/dbell.h>
> +#endif
>  
>  #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
>  int (*__debugger)(struct pt_regs *regs);
> @@ -1122,6 +1125,24 @@ void vsx_assist_exception(struct pt_regs *regs)
>  #endif /* CONFIG_VSX */
>  
>  #ifdef CONFIG_FSL_BOOKE
> +
> +void doorbell_exception(struct pt_regs *regs)
> +{
> +#ifdef CONFIG_SMP
> +	int cpu = smp_processor_id();
> +	int msg;
> +
> +	if (num_online_cpus() < 2)
> +		return;
> +
> +	for (msg = 0; msg < 4; msg++)
> +		if (test_and_clear_bit(msg, &dbell_smp_message[cpu]))
> +			smp_message_recv(msg);
> +#else
> +	printk(KERN_WARNING "Received doorbell on non-smp system\n");
> +#endif
> +}
> +
>  void CacheLockingException(struct pt_regs *regs, unsigned long address,
>  			   unsigned long error_code)
>  {
Kumar Gala - Feb. 23, 2009, 4:23 p.m.
On Feb 22, 2009, at 8:43 PM, Benjamin Herrenschmidt wrote:

> On Thu, 2009-02-12 at 17:54 -0600, Kumar Gala wrote:
>> The e500mc supports the new msgsnd/doorbell mechanisms that were  
>> added in
>> the Power ISA 2.05 architecture.  We use the normal level doorbell  
>> for
>> doing SMP IPIs at this point.
>
> Any reason why you don't use the tag ? I'm not too familiar with the
> doorbell stuff just yet but can't you use that instead of doing those
> atomics ?

tag just conveys the type of doorbell (normal, critical, etc.).  So  
for the 4 IPI msgs we support we need software to keep track.

> On thing we also need to look at is change our low level msg send to
> take a CPU mask.
>
> This will be better generically and we need a good cpu mask based IPI
> for the TLB stuff anyway. Volunteer ? :-)

yeah.. It something on the list :)

- k

>> Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
>> ---
>> arch/powerpc/include/asm/cputable.h  |    4 ++-
>> arch/powerpc/include/asm/dbell.h     |   43 ++++++++++++++++++++++++ 
>> +++++++++
>> arch/powerpc/kernel/Makefile         |    2 +-
>> arch/powerpc/kernel/dbell.c          |   44 ++++++++++++++++++++++++ 
>> ++++++++++
>> arch/powerpc/kernel/head_fsl_booke.S |    6 ++++-
>> arch/powerpc/kernel/traps.c          |   21 ++++++++++++++++
>> 6 files changed, 117 insertions(+), 3 deletions(-)
>> create mode 100644 arch/powerpc/include/asm/dbell.h
>> create mode 100644 arch/powerpc/kernel/dbell.c
>>
>> diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/ 
>> include/asm/cputable.h
>> index 4911104..fca1611 100644
>> --- a/arch/powerpc/include/asm/cputable.h
>> +++ b/arch/powerpc/include/asm/cputable.h
>> @@ -145,6 +145,7 @@ extern const char *powerpc_base_platform;
>> #define CPU_FTR_USE_TB			ASM_CONST(0x0000000000000040)
>> #define CPU_FTR_L2CSR			ASM_CONST(0x0000000000000080)
>> #define CPU_FTR_601			ASM_CONST(0x0000000000000100)
>> +#define CPU_FTR_DBELL			ASM_CONST(0x0000000000000200)
>> #define CPU_FTR_CAN_NAP			ASM_CONST(0x0000000000000400)
>> #define CPU_FTR_L3CR			ASM_CONST(0x0000000000000800)
>> #define CPU_FTR_L3_DISABLE_NAP		ASM_CONST(0x0000000000001000)
>> @@ -373,7 +374,8 @@ extern const char *powerpc_base_platform;
>> 	    CPU_FTR_NODSISRALIGN | CPU_FTR_NOEXECUTE)
>> #define CPU_FTRS_E500MC	(CPU_FTR_MAYBE_CAN_DOZE | CPU_FTR_USE_TB | \
>> 	    CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_NODSISRALIGN | \
>> -	    CPU_FTR_L2CSR | CPU_FTR_LWSYNC | CPU_FTR_NOEXECUTE)
>> +	    CPU_FTR_L2CSR | CPU_FTR_LWSYNC | CPU_FTR_NOEXECUTE | \
>> +	    CPU_FTR_DBELL)
>> #define CPU_FTRS_GENERIC_32	(CPU_FTR_COMMON | CPU_FTR_NODSISRALIGN)
>>
>> /* 64-bit CPUs */
>> diff --git a/arch/powerpc/include/asm/dbell.h b/arch/powerpc/ 
>> include/asm/dbell.h
>> new file mode 100644
>> index 0000000..501189a
>> --- /dev/null
>> +++ b/arch/powerpc/include/asm/dbell.h
>> @@ -0,0 +1,43 @@
>> +/*
>> + * Copyright 2009 Freescale Semicondutor, Inc.
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License
>> + * as published by the Free Software Foundation; either version
>> + * 2 of the License, or (at your option) any later version.
>> + *
>> + * provides masks and opcode images for use by code generation,  
>> emulation
>> + * and for instructions that older assemblers might not know about
>> + */
>> +#ifndef _ASM_POWERPC_DBELL_H
>> +#define _ASM_POWERPC_DBELL_H
>> +
>> +#include <linux/smp.h>
>> +#include <linux/threads.h>
>> +
>> +#include <asm/ppc-opcode.h>
>> +
>> +#define PPC_DBELL_MSG_BRDCAST	(0x04000000)
>> +#define PPC_DBELL_TYPE(x)	(((x) & 0xf) << 28)
>> +enum ppc_dbell {
>> +	PPC_DBELL = 0,		/* doorbell */
>> +	PPC_DBELL_CRIT = 1,	/* critical doorbell */
>> +	PPC_G_DBELL = 2,	/* guest doorbell */
>> +	PPC_G_DBELL_CRIT = 3,	/* guest critical doorbell */
>> +	PPC_G_DBELL_MC = 4,	/* guest mcheck doorbell */
>> +};
>> +
>> +#ifdef CONFIG_SMP
>> +extern unsigned long dbell_smp_message[NR_CPUS];
>> +extern void smp_dbell_message_pass(int target, int msg);
>> +#endif
>> +
>> +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));
>> +}
>> +
>> +#endif /* _ASM_POWERPC_DBELL_H */
>> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/ 
>> Makefile
>> index d159921..f420844 100644
>> --- a/arch/powerpc/kernel/Makefile
>> +++ b/arch/powerpc/kernel/Makefile
>> @@ -61,7 +61,7 @@ obj-$(CONFIG_HIBERNATION)	+= swsusp.o suspend.o \
>> obj64-$(CONFIG_HIBERNATION)	+= swsusp_asm64.o
>> obj-$(CONFIG_MODULES)		+= module.o module_$(CONFIG_WORD_SIZE).o
>> obj-$(CONFIG_44x)		+= cpu_setup_44x.o
>> -obj-$(CONFIG_FSL_BOOKE)		+= cpu_setup_fsl_booke.o
>> +obj-$(CONFIG_FSL_BOOKE)		+= cpu_setup_fsl_booke.o dbell.o
>>
>> extra-$(CONFIG_PPC_STD_MMU)	:= head_32.o
>> extra-$(CONFIG_PPC64)		:= head_64.o
>> diff --git a/arch/powerpc/kernel/dbell.c b/arch/powerpc/kernel/ 
>> dbell.c
>> new file mode 100644
>> index 0000000..1493734
>> --- /dev/null
>> +++ b/arch/powerpc/kernel/dbell.c
>> @@ -0,0 +1,44 @@
>> +/*
>> + * Author: Kumar Gala <galak@kernel.crashing.org>
>> + *
>> + * Copyright 2009 Freescale Semiconductor Inc.
>> + *
>> + * This program is free software; you can redistribute  it and/or  
>> modify it
>> + * under  the terms of  the GNU General  Public License as  
>> published by the
>> + * Free Software Foundation;  either version 2 of the  License, or  
>> (at your
>> + * option) any later version.
>> + */
>> +
>> +#include <linux/stddef.h>
>> +#include <linux/kernel.h>
>> +#include <linux/smp.h>
>> +#include <linux/threads.h>
>> +
>> +#include <asm/dbell.h>
>> +
>> +#ifdef CONFIG_SMP
>> +unsigned long dbell_smp_message[NR_CPUS];
>> +
>> +void smp_dbell_message_pass(int target, int msg)
>> +{
>> +	int i;
>> +
>> +	if(target < NR_CPUS) {
>> +		set_bit(msg, &dbell_smp_message[target]);
>> +		ppc_msgsnd(PPC_DBELL, 0, target);
>> +	}
>> +	else if(target == MSG_ALL_BUT_SELF) {
>> +		for_each_online_cpu(i) {
>> +			if (i == smp_processor_id())
>> +				continue;
>> +			set_bit(msg, &dbell_smp_message[i]);
>> +			ppc_msgsnd(PPC_DBELL, 0, i);
>> +		}
>> +	}
>> +	else { /* target == MSG_ALL */
>> +		for_each_online_cpu(i)
>> +			set_bit(msg, &dbell_smp_message[i]);
>> +		ppc_msgsnd(PPC_DBELL, PPC_DBELL_MSG_BRDCAST, 0);
>> +	}
>> +}
>> +#endif
>> diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/ 
>> kernel/head_fsl_booke.S
>> index 4ea6e1a..4c22620 100644
>> --- a/arch/powerpc/kernel/head_fsl_booke.S
>> +++ b/arch/powerpc/kernel/head_fsl_booke.S
>> @@ -698,7 +698,9 @@ interrupt_base:
>> 	/* Performance Monitor */
>> 	EXCEPTION(0x2060, PerformanceMonitor,  
>> performance_monitor_exception, EXC_XFER_STD)
>>
>> -	EXCEPTION(0x2070, Doorbell, unknown_exception, EXC_XFER_STD)
>> +	EXCEPTION(0x2070, Doorbell, doorbell_exception, EXC_XFER_STD)
>> +
>> +	CRITICAL_EXCEPTION(0x2080, CriticalDoorbell, unknown_exception)
>>
>> 	/* Debug Interrupt */
>> 	DEBUG_DEBUG_EXCEPTION
>> @@ -921,6 +923,8 @@ _GLOBAL(__setup_e500mc_ivors)
>> 	mtspr	SPRN_IVOR35,r3
>> 	li	r3,Doorbell@l
>> 	mtspr	SPRN_IVOR36,r3
>> +	li	r3,CriticalDoorbell@l
>> +	mtspr	SPRN_IVOR37,r3
>> 	sync
>> 	blr
>>
>> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/ 
>> traps.c
>> index 970d66e..678fbff 100644
>> --- a/arch/powerpc/kernel/traps.c
>> +++ b/arch/powerpc/kernel/traps.c
>> @@ -53,6 +53,9 @@
>> #endif
>> #include <asm/kexec.h>
>> #include <asm/ppc-opcode.h>
>> +#ifdef CONFIG_FSL_BOOKE
>> +#include <asm/dbell.h>
>> +#endif
>>
>> #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
>> int (*__debugger)(struct pt_regs *regs);
>> @@ -1122,6 +1125,24 @@ void vsx_assist_exception(struct pt_regs  
>> *regs)
>> #endif /* CONFIG_VSX */
>>
>> #ifdef CONFIG_FSL_BOOKE
>> +
>> +void doorbell_exception(struct pt_regs *regs)
>> +{
>> +#ifdef CONFIG_SMP
>> +	int cpu = smp_processor_id();
>> +	int msg;
>> +
>> +	if (num_online_cpus() < 2)
>> +		return;
>> +
>> +	for (msg = 0; msg < 4; msg++)
>> +		if (test_and_clear_bit(msg, &dbell_smp_message[cpu]))
>> +			smp_message_recv(msg);
>> +#else
>> +	printk(KERN_WARNING "Received doorbell on non-smp system\n");
>> +#endif
>> +}
>> +
>> void CacheLockingException(struct pt_regs *regs, unsigned long  
>> address,
>> 			   unsigned long error_code)
>> {

Patch

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 4911104..fca1611 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -145,6 +145,7 @@  extern const char *powerpc_base_platform;
 #define CPU_FTR_USE_TB			ASM_CONST(0x0000000000000040)
 #define CPU_FTR_L2CSR			ASM_CONST(0x0000000000000080)
 #define CPU_FTR_601			ASM_CONST(0x0000000000000100)
+#define CPU_FTR_DBELL			ASM_CONST(0x0000000000000200)
 #define CPU_FTR_CAN_NAP			ASM_CONST(0x0000000000000400)
 #define CPU_FTR_L3CR			ASM_CONST(0x0000000000000800)
 #define CPU_FTR_L3_DISABLE_NAP		ASM_CONST(0x0000000000001000)
@@ -373,7 +374,8 @@  extern const char *powerpc_base_platform;
 	    CPU_FTR_NODSISRALIGN | CPU_FTR_NOEXECUTE)
 #define CPU_FTRS_E500MC	(CPU_FTR_MAYBE_CAN_DOZE | CPU_FTR_USE_TB | \
 	    CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_NODSISRALIGN | \
-	    CPU_FTR_L2CSR | CPU_FTR_LWSYNC | CPU_FTR_NOEXECUTE)
+	    CPU_FTR_L2CSR | CPU_FTR_LWSYNC | CPU_FTR_NOEXECUTE | \
+	    CPU_FTR_DBELL)
 #define CPU_FTRS_GENERIC_32	(CPU_FTR_COMMON | CPU_FTR_NODSISRALIGN)
 
 /* 64-bit CPUs */
diff --git a/arch/powerpc/include/asm/dbell.h b/arch/powerpc/include/asm/dbell.h
new file mode 100644
index 0000000..501189a
--- /dev/null
+++ b/arch/powerpc/include/asm/dbell.h
@@ -0,0 +1,43 @@ 
+/*
+ * Copyright 2009 Freescale Semicondutor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * provides masks and opcode images for use by code generation, emulation
+ * and for instructions that older assemblers might not know about
+ */
+#ifndef _ASM_POWERPC_DBELL_H
+#define _ASM_POWERPC_DBELL_H
+
+#include <linux/smp.h>
+#include <linux/threads.h>
+
+#include <asm/ppc-opcode.h>
+
+#define PPC_DBELL_MSG_BRDCAST	(0x04000000)
+#define PPC_DBELL_TYPE(x)	(((x) & 0xf) << 28)
+enum ppc_dbell {
+	PPC_DBELL = 0,		/* doorbell */
+	PPC_DBELL_CRIT = 1,	/* critical doorbell */
+	PPC_G_DBELL = 2,	/* guest doorbell */
+	PPC_G_DBELL_CRIT = 3,	/* guest critical doorbell */
+	PPC_G_DBELL_MC = 4,	/* guest mcheck doorbell */
+};
+
+#ifdef CONFIG_SMP
+extern unsigned long dbell_smp_message[NR_CPUS];
+extern void smp_dbell_message_pass(int target, int msg);
+#endif
+
+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));
+}
+
+#endif /* _ASM_POWERPC_DBELL_H */
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index d159921..f420844 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -61,7 +61,7 @@  obj-$(CONFIG_HIBERNATION)	+= swsusp.o suspend.o \
 obj64-$(CONFIG_HIBERNATION)	+= swsusp_asm64.o
 obj-$(CONFIG_MODULES)		+= module.o module_$(CONFIG_WORD_SIZE).o
 obj-$(CONFIG_44x)		+= cpu_setup_44x.o
-obj-$(CONFIG_FSL_BOOKE)		+= cpu_setup_fsl_booke.o
+obj-$(CONFIG_FSL_BOOKE)		+= cpu_setup_fsl_booke.o dbell.o
 
 extra-$(CONFIG_PPC_STD_MMU)	:= head_32.o
 extra-$(CONFIG_PPC64)		:= head_64.o
diff --git a/arch/powerpc/kernel/dbell.c b/arch/powerpc/kernel/dbell.c
new file mode 100644
index 0000000..1493734
--- /dev/null
+++ b/arch/powerpc/kernel/dbell.c
@@ -0,0 +1,44 @@ 
+/*
+ * Author: Kumar Gala <galak@kernel.crashing.org>
+ *
+ * Copyright 2009 Freescale Semiconductor Inc.
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/stddef.h>
+#include <linux/kernel.h>
+#include <linux/smp.h>
+#include <linux/threads.h>
+
+#include <asm/dbell.h>
+
+#ifdef CONFIG_SMP
+unsigned long dbell_smp_message[NR_CPUS];
+
+void smp_dbell_message_pass(int target, int msg)
+{
+	int i;
+
+	if(target < NR_CPUS) {
+		set_bit(msg, &dbell_smp_message[target]);
+		ppc_msgsnd(PPC_DBELL, 0, target);
+	}
+	else if(target == MSG_ALL_BUT_SELF) {
+		for_each_online_cpu(i) {
+			if (i == smp_processor_id())
+				continue;
+			set_bit(msg, &dbell_smp_message[i]);
+			ppc_msgsnd(PPC_DBELL, 0, i);
+		}
+	}
+	else { /* target == MSG_ALL */
+		for_each_online_cpu(i)
+			set_bit(msg, &dbell_smp_message[i]);
+		ppc_msgsnd(PPC_DBELL, PPC_DBELL_MSG_BRDCAST, 0);
+	}
+}
+#endif
diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index 4ea6e1a..4c22620 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -698,7 +698,9 @@  interrupt_base:
 	/* Performance Monitor */
 	EXCEPTION(0x2060, PerformanceMonitor, performance_monitor_exception, EXC_XFER_STD)
 
-	EXCEPTION(0x2070, Doorbell, unknown_exception, EXC_XFER_STD)
+	EXCEPTION(0x2070, Doorbell, doorbell_exception, EXC_XFER_STD)
+
+	CRITICAL_EXCEPTION(0x2080, CriticalDoorbell, unknown_exception)
 
 	/* Debug Interrupt */
 	DEBUG_DEBUG_EXCEPTION
@@ -921,6 +923,8 @@  _GLOBAL(__setup_e500mc_ivors)
 	mtspr	SPRN_IVOR35,r3
 	li	r3,Doorbell@l
 	mtspr	SPRN_IVOR36,r3
+	li	r3,CriticalDoorbell@l
+	mtspr	SPRN_IVOR37,r3
 	sync
 	blr
 
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 970d66e..678fbff 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -53,6 +53,9 @@ 
 #endif
 #include <asm/kexec.h>
 #include <asm/ppc-opcode.h>
+#ifdef CONFIG_FSL_BOOKE
+#include <asm/dbell.h>
+#endif
 
 #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
 int (*__debugger)(struct pt_regs *regs);
@@ -1122,6 +1125,24 @@  void vsx_assist_exception(struct pt_regs *regs)
 #endif /* CONFIG_VSX */
 
 #ifdef CONFIG_FSL_BOOKE
+
+void doorbell_exception(struct pt_regs *regs)
+{
+#ifdef CONFIG_SMP
+	int cpu = smp_processor_id();
+	int msg;
+
+	if (num_online_cpus() < 2)
+		return;
+
+	for (msg = 0; msg < 4; msg++)
+		if (test_and_clear_bit(msg, &dbell_smp_message[cpu]))
+			smp_message_recv(msg);
+#else
+	printk(KERN_WARNING "Received doorbell on non-smp system\n");
+#endif
+}
+
 void CacheLockingException(struct pt_regs *regs, unsigned long address,
 			   unsigned long error_code)
 {