[tip:x86/apic] x86/apic: Add a single-target IPI function to the apic

tip-bot for Linus Torvalds
2015-11-05T14:44:03Z

Commit-ID: 539da7877275edb21a76aa02fb2c147eff02c559
Gitweb: http://git.kernel.org/tip/539da7877275edb21a76aa02fb2c147eff02c559
Author: Linus Torvalds <torvalds@linux-foundation.org>
AuthorDate: Wed, 4 Nov 2015 22:57:00 +0000
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 5 Nov 2015 13:07:51 +0100

x86/apic: Add a single-target IPI function to the apic

We still fall back on the "send mask" versions if an apic definition
doesn't have the single-target version, but at least this allows the
(trivial) case for the common clustered x2apic case.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Travis <travis@sgi.com>
Cc: Daniel J Blueman <daniel@numascale.com>
Link: http://lkml.kernel.org/r/20151104220848.737120838@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/include/asm/apic.h | 1 +
arch/x86/kernel/smp.c | 16 ++++++++++++++--
2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index a30316b..7f62ad4 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -303,6 +303,7 @@ struct apic {
unsigned int *apicid);

/* ipi */
+ void (*send_IPI)(int cpu, int vector);
void (*send_IPI_mask)(const struct cpumask *mask, int vector);
void (*send_IPI_mask_allbutself)(const struct cpumask *mask,
int vector);
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 12c8286..1dbf590 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -115,6 +115,18 @@ static atomic_t stopping_cpu = ATOMIC_INIT(-1);
static bool smp_no_nmi_ipi = false;

/*
+ * Helper wrapper: not all apic definitions support sending to
+ * a single CPU, so we fall back to sending to a mask.
+ */
+static void send_IPI_cpu(int cpu, int vector)
+{
+ if (apic->send_IPI)
+ apic->send_IPI(cpu, vector);
+ else
+ apic->send_IPI_mask(cpumask_of(cpu), vector);
+}
+
+/*
* this function sends a 'reschedule' IPI to another CPU.
* it goes straight through and wastes no time serializing
* anything. Worst case is that we lose a reschedule ...
@@ -125,12 +137,12 @@ static void native_smp_send_reschedule(int cpu)
WARN_ON(1);
return;
}
- apic->send_IPI_mask(cpumask_of(cpu), RESCHEDULE_VECTOR);
+ send_IPI_cpu(cpu, RESCHEDULE_VECTOR);
}

void native_send_call_func_single_ipi(int cpu)
{
- apic->send_IPI_mask(cpumask_of(cpu), CALL_FUNCTION_SINGLE_VECTOR);
+ send_IPI_cpu(cpu, CALL_FUNCTION_SINGLE_VECTOR);
}

void native_send_call_func_ipi(const struct cpumask *mask)