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Commit b87ac021 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc: Introduce msgsnd/doorbell barrier primitives 



POWER9 changes requirements and adds new instructions for
synchronization.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent b866cc21

arch/powerpc/include/asm/dbell.h

+22 −0
Original line number Diff line number Diff line
@@ -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);

arch/powerpc/include/asm/smp.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

arch/powerpc/kernel/dbell.c

+5 −3
Original line number Diff line number Diff line
@@ -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);

arch/powerpc/kernel/smp.c

+8 −2
Original line number Diff line number Diff line
@@ -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);