powerpc: Change the doorbell IPI calling convention

Change the doorbell callers to know about their msgsnd addressing,
rather than have them set a per-cpu target data tag at boot that gets
sent to the cause_ipi functions. The data is only used for doorbell IPI
functions, no other IPI types, so it makes sense to keep that detail
local to doorbell.

Have the platform code understand doorbell IPIs, rather than the
interrupt controller code understand them. Platform code can look at
capabilities it has available and decide which to use.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Author: npiggin

arch/powerpc/include/asm/dbell.h

@@ -35,8 +35,6 @@ enum ppc_dbell {
 #ifdef CONFIG_PPC_BOOK3S
 
 #define PPC_DBELL_MSGTYPE		PPC_DBELL_SERVER
-#define SPRN_DOORBELL_CPUTAG		SPRN_TIR
-#define PPC_DBELL_TAG_MASK		0x7f
 
 static inline void _ppc_msgsnd(u32 msg)
 {
@@ -49,8 +47,6 @@ static inline void _ppc_msgsnd(u32 msg)
 #else /* CONFIG_PPC_BOOK3S */
 
 #define PPC_DBELL_MSGTYPE		PPC_DBELL
-#define SPRN_DOORBELL_CPUTAG		SPRN_PIR
-#define PPC_DBELL_TAG_MASK		0x3fff
 
 static inline void _ppc_msgsnd(u32 msg)
 {
@@ -59,9 +55,10 @@ static inline void _ppc_msgsnd(u32 msg)
 
 #endif /* CONFIG_PPC_BOOK3S */
 
-extern void doorbell_cause_ipi(int cpu, unsigned long data);
+extern void doorbell_global_ipi(int cpu);
+extern void doorbell_core_ipi(int cpu);
+extern int doorbell_try_core_ipi(int cpu);
 extern void doorbell_exception(struct pt_regs *regs);
-extern void doorbell_setup_this_cpu(void);
 
 static inline void ppc_msgsnd(enum ppc_dbell type, u32 flags, u32 tag)
 {

arch/powerpc/include/asm/smp.h

@@ -40,7 +40,7 @@ extern int cpu_to_chip_id(int cpu);
 struct smp_ops_t {
 	void  (*message_pass)(int cpu, int msg);
 #ifdef CONFIG_PPC_SMP_MUXED_IPI
-	void  (*cause_ipi)(int cpu, unsigned long data);
+	void  (*cause_ipi)(int cpu);
 #endif
 	void  (*probe)(void);
 	int   (*kick_cpu)(int nr);
@@ -125,7 +125,6 @@ extern int smp_request_message_ipi(int virq, int message);
 extern const char *smp_ipi_name[];
 
 /* for irq controllers with only a single ipi */
-extern void smp_muxed_ipi_set_data(int cpu, unsigned long data);
 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);

arch/powerpc/include/asm/xics.h

@@ -57,7 +57,7 @@ struct icp_ops {
 	void (*teardown_cpu)(void);
 	void (*flush_ipi)(void);
 #ifdef CONFIG_SMP
-	void (*cause_ipi)(int cpu, unsigned long data);
+	void (*cause_ipi)(int cpu);
 	irq_handler_t ipi_action;
 #endif
 };

arch/powerpc/kernel/dbell.c

@@ -20,18 +20,60 @@
 #include <asm/kvm_ppc.h>
 
 #ifdef CONFIG_SMP
-void doorbell_setup_this_cpu(void)
+
+/*
+ * Doorbells must only be used if CPU_FTR_DBELL is available.
+ * msgsnd is used in HV, and msgsndp is used in !HV.
+ *
+ * These should be used by platform code that is aware of restrictions.
+ * Other arch code should use ->cause_ipi.
+ *
+ * doorbell_global_ipi() sends a dbell to any target CPU.
+ * Must be used only by architectures that address msgsnd target
+ * by PIR/get_hard_smp_processor_id.
+ */
+void doorbell_global_ipi(int cpu)
 {
-	unsigned long tag = mfspr(SPRN_DOORBELL_CPUTAG) & PPC_DBELL_TAG_MASK;
+	u32 tag = get_hard_smp_processor_id(cpu);
 
-	smp_muxed_ipi_set_data(smp_processor_id(), tag);
+	kvmppc_set_host_ipi(cpu, 1);
+	/* Order previous accesses vs. msgsnd, which is treated as a store */
+	mb();
+	ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, tag);
 }
 
-void doorbell_cause_ipi(int cpu, unsigned long data)
+/*
+ * doorbell_core_ipi() sends a dbell to a target CPU in the same core.
+ * Must be used only by architectures that address msgsnd target
+ * by TIR/cpu_thread_in_core.
+ */
+void doorbell_core_ipi(int cpu)
 {
+	u32 tag = cpu_thread_in_core(cpu);
+
+	kvmppc_set_host_ipi(cpu, 1);
 	/* Order previous accesses vs. msgsnd, which is treated as a store */
 	mb();
-	ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, data);
+	ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, tag);
+}
+
+/*
+ * Attempt to cause a core doorbell if destination is on the same core.
+ * Returns 1 on success, 0 on failure.
+ */
+int doorbell_try_core_ipi(int cpu)
+{
+	int this_cpu = get_cpu();
+	int ret = 0;
+
+	if (cpumask_test_cpu(cpu, cpu_sibling_mask(this_cpu))) {
+		doorbell_core_ipi(cpu);
+		ret = 1;
+	}
+
+	put_cpu();
+
+	return ret;
 }
 
 void doorbell_exception(struct pt_regs *regs)

arch/powerpc/kernel/smp.c

@@ -39,6 +39,7 @@
 #include <asm/irq.h>
 #include <asm/hw_irq.h>
 #include <asm/kvm_ppc.h>
+#include <asm/dbell.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/prom.h>
@@ -211,17 +212,9 @@ int smp_request_message_ipi(int virq, int msg)
 #ifdef CONFIG_PPC_SMP_MUXED_IPI
 struct cpu_messages {
 	long messages;			/* current messages */
-	unsigned long data;		/* data for cause ipi */
 };
 static DEFINE_PER_CPU_SHARED_ALIGNED(struct cpu_messages, ipi_message);
 
-void smp_muxed_ipi_set_data(int cpu, unsigned long data)
-{
-	struct cpu_messages *info = &per_cpu(ipi_message, cpu);
-
-	info->data = data;
-}
-
 void smp_muxed_ipi_set_message(int cpu, int msg)
 {
 	struct cpu_messages *info = &per_cpu(ipi_message, cpu);
@@ -236,14 +229,13 @@ void smp_muxed_ipi_set_message(int cpu, int msg)
 
 void smp_muxed_ipi_message_pass(int cpu, int msg)
 {
-	struct cpu_messages *info = &per_cpu(ipi_message, cpu);
-
 	smp_muxed_ipi_set_message(cpu, msg);
+
 	/*
 	 * cause_ipi functions are required to include a full barrier
 	 * before doing whatever causes the IPI.
 	 */
-	smp_ops->cause_ipi(cpu, info->data);
+	smp_ops->cause_ipi(cpu);
 }
 
 #ifdef __BIG_ENDIAN__
@@ -254,11 +246,12 @@ void smp_muxed_ipi_message_pass(int cpu, int msg)
 
 irqreturn_t smp_ipi_demux(void)
 {
-	struct cpu_messages *info = this_cpu_ptr(&ipi_message);
+	struct cpu_messages *info;
 	unsigned long all;
 
 	mb();	/* order any irq clear */
 
+	info = this_cpu_ptr(&ipi_message);
 	do {
 		all = xchg(&info->messages, 0);
 #if defined(CONFIG_KVM_XICS) && defined(CONFIG_KVM_BOOK3S_HV_POSSIBLE)

arch/powerpc/platforms/85xx/smp.c

@@ -461,16 +461,9 @@ static void mpc85xx_smp_machine_kexec(struct kimage *image)
 }
 #endif /* CONFIG_KEXEC_CORE */
 
-static void smp_85xx_basic_setup(int cpu_nr)
-{
-	if (cpu_has_feature(CPU_FTR_DBELL))
-		doorbell_setup_this_cpu();
-}
-
 static void smp_85xx_setup_cpu(int cpu_nr)
 {
 	mpic_setup_this_cpu();
-	smp_85xx_basic_setup(cpu_nr);
 }
 
 void __init mpc85xx_smp_init(void)
@@ -484,15 +477,15 @@ void __init mpc85xx_smp_init(void)
 		smp_85xx_ops.setup_cpu = smp_85xx_setup_cpu;
 		smp_85xx_ops.message_pass = smp_mpic_message_pass;
 	} else
-		smp_85xx_ops.setup_cpu = smp_85xx_basic_setup;
+		smp_85xx_ops.setup_cpu = NULL;
 
 	if (cpu_has_feature(CPU_FTR_DBELL)) {
 		/*
 		 * If left NULL, .message_pass defaults to
 		 * smp_muxed_ipi_message_pass
 		 */
 		smp_85xx_ops.message_pass = NULL;
-		smp_85xx_ops.cause_ipi = doorbell_cause_ipi;
+		smp_85xx_ops.cause_ipi = doorbell_global_ipi;
 		smp_85xx_ops.probe = NULL;
 	}
 

arch/powerpc/platforms/powermac/smp.c

@@ -172,7 +172,7 @@ static irqreturn_t psurge_ipi_intr(int irq, void *d)
 	return IRQ_HANDLED;
 }
 
-static void smp_psurge_cause_ipi(int cpu, unsigned long data)
+static void smp_psurge_cause_ipi(int cpu)
 {
 	psurge_set_ipi(cpu);
 }

arch/powerpc/platforms/powernv/smp.c

@@ -53,11 +53,6 @@ static void pnv_smp_setup_cpu(int cpu)
 		xive_smp_setup_cpu();
 	else if (cpu != boot_cpuid)
 		xics_setup_cpu();
-
-#ifdef CONFIG_PPC_DOORBELL
-	if (cpu_has_feature(CPU_FTR_DBELL))
-		doorbell_setup_this_cpu();
-#endif
 }
 
 static int pnv_smp_kick_cpu(int nr)
@@ -254,17 +249,31 @@ static int pnv_smp_prepare_cpu(int cpu)
 	return 0;
 }
 
+static void pnv_cause_ipi(int cpu)
+{
+	if (doorbell_try_core_ipi(cpu))
+		return;
+
+	icp_ops->cause_ipi(cpu);
+}
+
 static void __init pnv_smp_probe(void)
 {
 	if (xive_enabled())
 		xive_smp_probe();
 	else
 		xics_smp_probe();
+
+	if (cpu_has_feature(CPU_FTR_DBELL) && !cpu_has_feature(CPU_FTR_ARCH_300)) {
+		smp_ops->cause_ipi = pnv_cause_ipi;
+	} else {
+		smp_ops->cause_ipi = icp_ops->cause_ipi;
+	}
 }
 
 static struct smp_ops_t pnv_smp_ops = {
-	.message_pass	= smp_muxed_ipi_message_pass,
-	.cause_ipi	= NULL, /* Filled at runtime by xi{cs,ve}_smp_probe() */
+	.message_pass	= NULL, /* Use smp_muxed_ipi_message_pass */
+	.cause_ipi	= NULL,	/* Filled at runtime by pnv_smp_probe() */
 	.probe		= pnv_smp_probe,
 	.prepare_cpu	= pnv_smp_prepare_cpu,
 	.kick_cpu	= pnv_smp_kick_cpu,

arch/powerpc/platforms/pseries/smp.c

@@ -55,11 +55,6 @@
  */
 static cpumask_var_t of_spin_mask;
 
-/*
- * If we multiplex IPI mechanisms, store the appropriate XICS IPI mechanism here
- */
-static void  (*xics_cause_ipi)(int cpu, unsigned long data);
-
 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
 int smp_query_cpu_stopped(unsigned int pcpu)
 {
@@ -143,8 +138,6 @@ static void smp_setup_cpu(int cpu)
 {
 	if (cpu != boot_cpuid)
 		xics_setup_cpu();
-	if (cpu_has_feature(CPU_FTR_DBELL))
-		doorbell_setup_this_cpu();
 
 	if (firmware_has_feature(FW_FEATURE_SPLPAR))
 		vpa_init(cpu);
@@ -187,23 +180,23 @@ static int smp_pSeries_kick_cpu(int nr)
 	return 0;
 }
 
-/* Only used on systems that support multiple IPI mechanisms */
-static void pSeries_cause_ipi_mux(int cpu, unsigned long data)
+static void smp_pseries_cause_ipi(int cpu)
 {
-	if (cpumask_test_cpu(cpu, cpu_sibling_mask(smp_processor_id())))
-		doorbell_cause_ipi(cpu, data);
-	else
-		xics_cause_ipi(cpu, data);
+	/* POWER9 should not use this handler */
+	if (doorbell_try_core_ipi(cpu))
+		return;
+
+	icp_ops->cause_ipi(cpu);
 }
 
 static __init void pSeries_smp_probe(void)
 {
 	xics_smp_probe();
 
-	if (cpu_has_feature(CPU_FTR_DBELL)) {
-		xics_cause_ipi = smp_ops->cause_ipi;
-		smp_ops->cause_ipi = pSeries_cause_ipi_mux;
-	}
+	if (cpu_has_feature(CPU_FTR_DBELL))
+		smp_ops->cause_ipi = smp_pseries_cause_ipi;
+	else
+		smp_ops->cause_ipi = icp_ops->cause_ipi;
 }
 
 static struct smp_ops_t pseries_smp_ops = {

arch/powerpc/sysdev/xics/icp-hv.c

@@ -138,7 +138,7 @@ static void icp_hv_set_cpu_priority(unsigned char cppr)
 
 #ifdef CONFIG_SMP
 
-static void icp_hv_cause_ipi(int cpu, unsigned long data)
+static void icp_hv_cause_ipi(int cpu)
 {
 	icp_hv_set_qirr(cpu, IPI_PRIORITY);
 }