Message-ID: <46CEBF55.3070703@bull.net>
Date: Fri, 24 Aug 2007 13:21:57 +0200
From: Laurent Vivier <Laurent.Vivier@bull.net>
Organization: Bull S.A.S.
User-Agent: Thunderbird 1.5.0.2 (X11/20060420)
MIME-Version: 1.0
To: Andi Kleen <ak@suse.de>
Cc: discuss@x86-64.org, linux-kernel <linux-kernel@vger.kernel.org>,
       Avi Kivity <avi@qumranet.com>
Subject: [PATCH][RESEND] Implement missing x86_64 function smp_call_function_mask()
References: <46CD38E5.4000704@bull.net> <200708231125.38816.ak@suse.de> <46CD54B5.6050200@bull.net> <20070823105628.GM8058@bingen.suse.de>
In-Reply-To: <20070823105628.GM8058@bingen.suse.de>
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This patch defines the missing function smp_call_function_mask() for x86_64,
this is more or less a cut&paste of i386 function. It removes also some
duplicate code.

This function is needed by KVM to execute a function on all CPUs.

 arch/x86_64/kernel/smp.c |  118 ++++++++++++++++++++++++-----------------------
 include/asm-x86_64/smp.h |    2
 2 files changed, 64 insertions(+), 56 deletions(-)

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>

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 name="smp_call_function_mask-x86_64"
Content-Disposition: inline;
 filename="smp_call_function_mask-x86_64"

Index: kvm/arch/x86_64/kernel/smp.c
===================================================================
--- kvm.orig/arch/x86_64/kernel/smp.c	2007-08-23 17:36:13.000000000 +0200
+++ kvm/arch/x86_64/kernel/smp.c	2007-08-23 17:37:56.000000000 +0200
@@ -321,17 +321,30 @@ void unlock_ipi_call_lock(void)
 }
 
 /*
- * this function sends a 'generic call function' IPI to one other CPU
- * in the system.
- *
- * cpu is a standard Linux logical CPU number.
+ * this function sends a 'generic call function' IPI to all other CPU
+ * of the system defined in the mask.
  */
-static void
-__smp_call_function_single(int cpu, void (*func) (void *info), void *info,
-				int nonatomic, int wait)
+
+static int
+__smp_call_function_mask(cpumask_t mask,
+			 void (*func)(void *), void *info,
+			 int wait)
 {
 	struct call_data_struct data;
-	int cpus = 1;
+	cpumask_t allbutself;
+	int cpus;
+
+	/* Can deadlock when called with interrupts disabled */
+	WARN_ON(irqs_disabled());
+
+	allbutself = cpu_online_map;
+	cpu_clear(smp_processor_id(), allbutself);
+
+	cpus_and(mask, mask, allbutself);
+	cpus = cpus_weight(mask);
+
+	if (!cpus)
+		return 0;
 
 	data.func = func;
 	data.info = info;
@@ -342,19 +355,51 @@ __smp_call_function_single(int cpu, void
 
 	call_data = &data;
 	wmb();
-	/* Send a message to all other CPUs and wait for them to respond */
-	send_IPI_mask(cpumask_of_cpu(cpu), CALL_FUNCTION_VECTOR);
+
+	/* Send a message to other CPUs */
+	if (cpus_equal(mask, allbutself))
+		send_IPI_allbutself(CALL_FUNCTION_VECTOR);
+	else
+		send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
 
 	/* Wait for response */
 	while (atomic_read(&data.started) != cpus)
 		cpu_relax();
 
 	if (!wait)
-		return;
+		return 0;
 
 	while (atomic_read(&data.finished) != cpus)
 		cpu_relax();
+
+	return 0;
+}
+/**
+ * smp_call_function_mask(): Run a function on a set of other CPUs.
+ * @mask: The set of cpus to run on.  Must not include the current cpu.
+ * @func: The function to run. This must be fast and non-blocking.
+ * @info: An arbitrary pointer to pass to the function.
+ * @wait: If true, wait (atomically) until function has completed on other CPUs.
+ *
+ * Returns 0 on success, else a negative status code.
+ *
+ * If @wait is true, then returns once @func has returned; otherwise
+ * it returns just before the target cpu calls @func.
+ *
+ * You must not call this function with disabled interrupts or from a
+ * hardware interrupt handler or from a bottom half handler.
+ */
+int smp_call_function_mask(cpumask_t mask,
+			   void (*func)(void *), void *info,
+			   int wait)
+{
+	int ret;
+	spin_lock(&call_lock);
+	ret = __smp_call_function_mask(mask, func, info, wait);
+	spin_unlock(&call_lock);
+	return ret;
 }
+EXPORT_SYMBOL(smp_call_function_mask);
 
 /*
  * smp_call_function_single - Run a function on a specific CPU
@@ -373,6 +418,7 @@ int smp_call_function_single (int cpu, v
 	int nonatomic, int wait)
 {
 	/* prevent preemption and reschedule on another processor */
+	int ret;
 	int me = get_cpu();
 
 	/* Can deadlock when called with interrupts disabled */
@@ -386,51 +432,14 @@ int smp_call_function_single (int cpu, v
 		return 0;
 	}
 
-	spin_lock(&call_lock);
-	__smp_call_function_single(cpu, func, info, nonatomic, wait);
-	spin_unlock(&call_lock);
+	ret = smp_call_function_mask(cpumask_of_cpu(cpu), func, info, wait);
+
 	put_cpu();
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL(smp_call_function_single);
 
 /*
- * this function sends a 'generic call function' IPI to all other CPUs
- * in the system.
- */
-static void __smp_call_function (void (*func) (void *info), void *info,
-				int nonatomic, int wait)
-{
-	struct call_data_struct data;
-	int cpus = num_online_cpus()-1;
-
-	if (!cpus)
-		return;
-
-	data.func = func;
-	data.info = info;
-	atomic_set(&data.started, 0);
-	data.wait = wait;
-	if (wait)
-		atomic_set(&data.finished, 0);
-
-	call_data = &data;
-	wmb();
-	/* Send a message to all other CPUs and wait for them to respond */
-	send_IPI_allbutself(CALL_FUNCTION_VECTOR);
-
-	/* Wait for response */
-	while (atomic_read(&data.started) != cpus)
-		cpu_relax();
-
-	if (!wait)
-		return;
-
-	while (atomic_read(&data.finished) != cpus)
-		cpu_relax();
-}
-
-/*
  * smp_call_function - run a function on all other CPUs.
  * @func: The function to run. This must be fast and non-blocking.
  * @info: An arbitrary pointer to pass to the function.
@@ -448,10 +457,7 @@ static void __smp_call_function (void (*
 int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
 			int wait)
 {
-	spin_lock(&call_lock);
-	__smp_call_function(func,info,nonatomic,wait);
-	spin_unlock(&call_lock);
-	return 0;
+	return smp_call_function_mask(cpu_online_map, func, info, wait);
 }
 EXPORT_SYMBOL(smp_call_function);
 
@@ -478,7 +484,7 @@ void smp_send_stop(void)
 	/* Don't deadlock on the call lock in panic */
 	nolock = !spin_trylock(&call_lock);
 	local_irq_save(flags);
-	__smp_call_function(stop_this_cpu, NULL, 0, 0);
+	__smp_call_function_mask(cpu_online_map, stop_this_cpu, NULL, 0);
 	if (!nolock)
 		spin_unlock(&call_lock);
 	disable_local_APIC();
Index: kvm/include/asm-x86_64/smp.h
===================================================================
--- kvm.orig/include/asm-x86_64/smp.h	2007-08-23 17:36:13.000000000 +0200
+++ kvm/include/asm-x86_64/smp.h	2007-08-23 17:37:56.000000000 +0200
@@ -37,6 +37,8 @@ extern void lock_ipi_call_lock(void);
 extern void unlock_ipi_call_lock(void);
 extern int smp_num_siblings;
 extern void smp_send_reschedule(int cpu);
+extern int smp_call_function_mask(cpumask_t mask, void (*func)(void *),
+				  void *info, int wait);
 
 extern cpumask_t cpu_sibling_map[NR_CPUS];
 extern cpumask_t cpu_core_map[NR_CPUS];

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