From a9af97aa0a12c30178dd7ad9af8887d5b9c4647b Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@gmail.com>
Date: Tue, 13 Jun 2017 23:05:48 +1000
Subject: [PATCH] powerpc/64s: msgclr when handling doorbell exceptions from
system reset
References: bsc#1065729
Patch-mainline: v4.13-rc1
Git-commit: a9af97aa0a12c30178dd7ad9af8887d5b9c4647b
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.
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.
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
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 3b6bbf5a8683..4e2cf719c9b2 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -220,6 +220,7 @@
#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 0x7c20070d
@@ -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 2f700a15bfa3..1752beefee69 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1612,6 +1612,25 @@ 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
@@ -1636,13 +1655,13 @@ _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
--
2.13.6