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powerpc: Introduce msgsnd/doorbell barrier primitives 

POWER9 changes requirements and adds new instructions for
synchronization.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2017-04-13 20:16:22 +10:00 committed by Michael Ellerman
parent b866cc2199
commit b87ac02183
4 changed files with 36 additions and 5 deletions
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22
arch/powerpc/include/asm/dbell.h
View File

@ -44,6 +44,17 @@ static inline void _ppc_msgsnd(u32 msg)
__asm__ __volatile__ (PPC_MSGSNDP(%0) : : "r" (msg));
}
/* sync before sending message */
static inline void ppc_msgsnd_sync(void)
{
__asm__ __volatile__ ("sync" : : : "memory");
}
/* sync after taking message interrupt */
static inline void ppc_msgsync(void)
{
}
#else /* CONFIG_PPC_BOOK3S */
#define PPC_DBELL_MSGTYPE PPC_DBELL
@ -53,6 +64,17 @@ static inline void _ppc_msgsnd(u32 msg)
__asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
}
/* sync before sending message */
static inline void ppc_msgsnd_sync(void)
{
__asm__ __volatile__ ("sync" : : : "memory");
}
/* sync after taking message interrupt */
static inline void ppc_msgsync(void)
{
}
#endif /* CONFIG_PPC_BOOK3S */
extern void doorbell_global_ipi(int cpu);

1
arch/powerpc/include/asm/smp.h
View File

@ -128,6 +128,7 @@ extern const char *smp_ipi_name[];
extern void smp_muxed_ipi_message_pass(int cpu, int msg);
extern void smp_muxed_ipi_set_message(int cpu, int msg);
extern irqreturn_t smp_ipi_demux(void);
extern irqreturn_t smp_ipi_demux_relaxed(void);
void smp_init_pSeries(void);
void smp_init_cell(void);

8
arch/powerpc/kernel/dbell.c
View File

@ -38,7 +38,7 @@ void doorbell_global_ipi(int cpu)
kvmppc_set_host_ipi(cpu, 1);
/* Order previous accesses vs. msgsnd, which is treated as a store */
mb();
ppc_msgsnd_sync();
ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, tag);
}
@ -53,7 +53,7 @@ void doorbell_core_ipi(int cpu)
kvmppc_set_host_ipi(cpu, 1);
/* Order previous accesses vs. msgsnd, which is treated as a store */
mb();
ppc_msgsnd_sync();
ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, tag);
}
@ -82,12 +82,14 @@ void doorbell_exception(struct pt_regs *regs)
irq_enter();
ppc_msgsync();
may_hard_irq_enable();
kvmppc_set_host_ipi(smp_processor_id(), 0);
__this_cpu_inc(irq_stat.doorbell_irqs);
smp_ipi_demux();
smp_ipi_demux_relaxed(); /* already performed the barrier */
irq_exit();
set_irq_regs(old_regs);

10
arch/powerpc/kernel/smp.c
View File

@ -245,12 +245,18 @@ void smp_muxed_ipi_message_pass(int cpu, int msg)
#endif
irqreturn_t smp_ipi_demux(void)
{
mb(); /* order any irq clear */
return smp_ipi_demux_relaxed();
}
/* sync-free variant. Callers should ensure synchronization */
irqreturn_t smp_ipi_demux_relaxed(void)
{
struct cpu_messages *info;
unsigned long all;
mb(); /* order any irq clear */
info = this_cpu_ptr(&ipi_message);
do {
all = xchg(&info->messages, 0);