On Mon, Jun 12, 2017 at 09:58:26AM +1000, Nicholas Piggin wrote:
> msgsnd doorbell exceptions are cleared when the doorbell interrupt is
> taken. However if a doorbell exception causes a system reset interrupt
> wake from power saving state, the message is not cleared. Processing
> the doorbell from the system reset interrupt requires msgclr to avoid
> taking the exception again.
>
So you are clearing the doorbell message in this patch.
> Testing this plus the previous wakup direct patch gives:
>
> original wakeup direct msgclr
> Different threads, same core: 315k/s 264k/s 345k/s
> Different cores: 235k/s 242k/s 242k/s
>
> Net speedup is +10% for same core, and +3% for different core.
This is good speedup.
Reviewed-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
> ---
> arch/powerpc/include/asm/dbell.h | 13 +++++++++++++
> arch/powerpc/include/asm/ppc-opcode.h | 3 +++
> arch/powerpc/kernel/asm-offsets.c | 1 +
> arch/powerpc/kernel/exceptions-64s.S | 23 +++++++++++++++++++++--
> 4 files changed, 38 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/dbell.h
> b/arch/powerpc/include/asm/dbell.h
> index f70cbfe0ec04..9f2ae0d25e15 100644
> --- a/arch/powerpc/include/asm/dbell.h
> +++ b/arch/powerpc/include/asm/dbell.h
> @@ -56,6 +56,19 @@ static inline void ppc_msgsync(void)
> : : "i" (CPU_FTR_HVMODE|CPU_FTR_ARCH_300));
> }
>
> +static inline void _ppc_msgclr(u32 msg)
> +{
> + __asm__ __volatile__ (ASM_FTR_IFSET(PPC_MSGCLR(%1), PPC_MSGCLRP(%1), %0)
> + : : "i" (CPU_FTR_HVMODE), "r" (msg));
> +}
> +
> +static inline void ppc_msgclr(enum ppc_dbell type)
> +{
> + u32 msg = PPC_DBELL_TYPE(type);
> +
> + _ppc_msgclr(msg);
> +}
> +
> #else /* CONFIG_PPC_BOOK3S */
>
> #define PPC_DBELL_MSGTYPE PPC_DBELL
> diff --git a/arch/powerpc/include/asm/ppc-opcode.h
> b/arch/powerpc/include/asm/ppc-opcode.h
> index 3a8d278e7421..3b29c54e51fa 100644
> --- a/arch/powerpc/include/asm/ppc-opcode.h
> +++ b/arch/powerpc/include/asm/ppc-opcode.h
> @@ -221,6 +221,7 @@
> #define PPC_INST_MSGCLR 0x7c0001dc
> #define PPC_INST_MSGSYNC 0x7c0006ec
> #define PPC_INST_MSGSNDP 0x7c00011c
> +#define PPC_INST_MSGCLRP 0x7c00015c
> #define PPC_INST_MTTMR 0x7c0003dc
> #define PPC_INST_NOP 0x60000000
> #define PPC_INST_PASTE 0x7c00070c
> @@ -409,6 +410,8 @@
> ___PPC_RB(b))
> #define PPC_MSGSNDP(b) stringify_in_c(.long PPC_INST_MSGSNDP |
> \
> ___PPC_RB(b))
> +#define PPC_MSGCLRP(b) stringify_in_c(.long PPC_INST_MSGCLRP |
> \
> + ___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/kernel/asm-offsets.c
> b/arch/powerpc/kernel/asm-offsets.c
> index e15c178ba079..9624851ca276 100644
> --- a/arch/powerpc/kernel/asm-offsets.c
> +++ b/arch/powerpc/kernel/asm-offsets.c
> @@ -746,6 +746,7 @@ int main(void)
> #endif
>
> DEFINE(PPC_DBELL_SERVER, PPC_DBELL_SERVER);
> + DEFINE(PPC_DBELL_MSGTYPE, PPC_DBELL_MSGTYPE);
>
> #ifdef CONFIG_PPC_8xx
> DEFINE(VIRT_IMMR_BASE, (u64)__fix_to_virt(FIX_IMMR_BASE));
> diff --git a/arch/powerpc/kernel/exceptions-64s.S
> b/arch/powerpc/kernel/exceptions-64s.S
> index ae418b85c17c..a04ee0d7f88e 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -1552,6 +1552,25 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
> b 1b
>
> /*
> + * When doorbell is triggered from system reset wakeup, the message is
> + * not cleared, so it would fire again when EE is enabled.
> + *
> + * When coming from local_irq_enable, there may be the same problem if
> + * we were hard disabled.
> + *
> + * Execute msgclr to clear pending exceptions before handling it.
> + */
> +h_doorbell_common_msgclr:
> + LOAD_REG_IMMEDIATE(r3, PPC_DBELL_MSGTYPE << (63-36))
> + PPC_MSGCLR(3)
> + b h_doorbell_common
> +
> +doorbell_super_common_msgclr:
> + LOAD_REG_IMMEDIATE(r3, PPC_DBELL_MSGTYPE << (63-36))
> + PPC_MSGCLRP(3)
> + b doorbell_super_common
> +
> +/*
> * Called from arch_local_irq_enable when an interrupt needs
> * to be resent. r3 contains 0x500, 0x900, 0xa00 or 0xe80 to indicate
> * which kind of interrupt. MSR:EE is already off. We generate a
> @@ -1576,13 +1595,13 @@ _GLOBAL(__replay_interrupt)
> beq hardware_interrupt_common
> BEGIN_FTR_SECTION
> cmpwi r3,0xe80
> - beq h_doorbell_common
> + beq h_doorbell_common_msgclr
> cmpwi r3,0xea0
> beq h_virt_irq_common
> cmpwi r3,0xe60
> beq hmi_exception_common
> FTR_SECTION_ELSE
> cmpwi r3,0xa00
> - beq doorbell_super_common
> + beq doorbell_super_common_msgclr
> ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
> blr
> --
> 2.11.0
>
