diff mbox

[v2,6/6] ARM: mach-virt: add SMP support using PSCI

Message ID 1355762141-29616-7-git-send-email-will.deacon@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Will Deacon Dec. 17, 2012, 4:35 p.m. UTC
This patch adds support for SMP to mach-virt using the PSCI
infrastructure.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/mach-virt/Kconfig   |  1 +
 arch/arm/mach-virt/Makefile  |  1 +
 arch/arm/mach-virt/platsmp.c | 76 ++++++++++++++++++++++++++++++++++++++++++++
 arch/arm/mach-virt/virt.c    |  6 ++++
 4 files changed, 84 insertions(+)
 create mode 100644 arch/arm/mach-virt/platsmp.c

Comments

Nicolas Pitre Dec. 17, 2012, 9:45 p.m. UTC | #1
On Mon, 17 Dec 2012, Will Deacon wrote:

> This patch adds support for SMP to mach-virt using the PSCI
> infrastructure.
> 
> Signed-off-by: Will Deacon <will.deacon@arm.com>
> ---
>  arch/arm/mach-virt/Kconfig   |  1 +
>  arch/arm/mach-virt/Makefile  |  1 +
>  arch/arm/mach-virt/platsmp.c | 76 ++++++++++++++++++++++++++++++++++++++++++++
>  arch/arm/mach-virt/virt.c    |  6 ++++
>  4 files changed, 84 insertions(+)
>  create mode 100644 arch/arm/mach-virt/platsmp.c
> 
> diff --git a/arch/arm/mach-virt/Kconfig b/arch/arm/mach-virt/Kconfig
> index a568a2a..8958f0d 100644
> --- a/arch/arm/mach-virt/Kconfig
> +++ b/arch/arm/mach-virt/Kconfig
> @@ -3,6 +3,7 @@ config ARCH_VIRT
>  	select ARCH_WANT_OPTIONAL_GPIOLIB
>  	select ARM_GIC
>  	select ARM_ARCH_TIMER
> +	select ARM_PSCI
>  	select HAVE_SMP
>  	select CPU_V7
>  	select SPARSE_IRQ
> diff --git a/arch/arm/mach-virt/Makefile b/arch/arm/mach-virt/Makefile
> index 7ddbfa6..042afc1 100644
> --- a/arch/arm/mach-virt/Makefile
> +++ b/arch/arm/mach-virt/Makefile
> @@ -3,3 +3,4 @@
>  #
>  
>  obj-y					:= virt.o
> +obj-$(CONFIG_SMP)			+= platsmp.o
> diff --git a/arch/arm/mach-virt/platsmp.c b/arch/arm/mach-virt/platsmp.c
> new file mode 100644
> index 0000000..930362b
> --- /dev/null
> +++ b/arch/arm/mach-virt/platsmp.c
> @@ -0,0 +1,76 @@
> +/*
> + * Dummy Virtual Machine - does what it says on the tin.
> + *
> + * Copyright (C) 2012 ARM Ltd
> + * Author: Will Deacon <will.deacon@arm.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/smp.h>
> +#include <linux/of.h>
> +
> +#include <asm/psci.h>
> +#include <asm/smp_plat.h>
> +#include <asm/hardware/gic.h>
> +
> +extern void secondary_startup(void);
> +
> +/*
> + * Enumerate the possible CPU set from the device tree.
> + */
> +static void __init virt_smp_init_cpus(void)
> +{
> +	struct device_node *dn = NULL;
> +	int cpu = 0;
> +
> +	while ((dn = of_find_node_by_type(dn, "cpu"))) {
> +		if (cpu < NR_CPUS)
> +			set_cpu_possible(cpu, true);
> +		cpu++;
> +	}
> +
> +	/* sanity check */
> +	if (cpu > NR_CPUS)
> +		pr_warning("no. of cores (%d) greater than configured maximum "
> +			   "of %d - clipping\n",
> +			   cpu, NR_CPUS);

Since commit 5587164eea you shouldn't need any of the above.

> +	set_smp_cross_call(gic_raise_softirq);
> +}
> +
> +static void __init virt_smp_prepare_cpus(unsigned int max_cpus)
> +{
> +}
> +
> +static int __cpuinit virt_boot_secondary(unsigned int cpu,
> +					 struct task_struct *idle)
> +{
> +	if (psci_ops.cpu_on)
> +		return psci_ops.cpu_on(cpu_logical_map(cpu),
> +				       __pa(secondary_startup));
> +	return -ENODEV;
> +}
> +
> +static void __cpuinit virt_secondary_init(unsigned int cpu)
> +{
> +	gic_secondary_init(0);
> +}
> +
> +struct smp_operations __initdata virt_smp_ops = {
> +	.smp_init_cpus		= virt_smp_init_cpus,
> +	.smp_prepare_cpus	= virt_smp_prepare_cpus,
> +	.smp_secondary_init	= virt_secondary_init,
> +	.smp_boot_secondary	= virt_boot_secondary,
> +};
> diff --git a/arch/arm/mach-virt/virt.c b/arch/arm/mach-virt/virt.c
> index 174b9da..d764835 100644
> --- a/arch/arm/mach-virt/virt.c
> +++ b/arch/arm/mach-virt/virt.c
> @@ -20,6 +20,7 @@
>  
>  #include <linux/of_irq.h>
>  #include <linux/of_platform.h>
> +#include <linux/smp.h>
>  
>  #include <asm/arch_timer.h>
>  #include <asm/hardware/gic.h>
> @@ -56,10 +57,15 @@ static struct sys_timer virt_timer = {
>  	.init = virt_timer_init,
>  };
>  
> +#ifdef CONFIG_SMP
> +extern struct smp_operations virt_smp_ops;
> +#endif

You don't need to surround prototype declaration here, unless your goal 
was to define a dummy virt_smp_ops when CONFIG_SMP is not selected?
Otherwise the reference below would break compilation.

> +
>  DT_MACHINE_START(VIRT, "Dummy Virtual Machine")
>  	.init_irq	= gic_init_irq,
>  	.handle_irq     = gic_handle_irq,
>  	.timer		= &virt_timer,
>  	.init_machine	= virt_init,
> +	.smp		= smp_ops(virt_smp_ops),
>  	.dt_compat	= virt_dt_match,
>  MACHINE_END
> -- 
> 1.8.0
>
Will Deacon Dec. 18, 2012, 10:49 a.m. UTC | #2
On Mon, Dec 17, 2012 at 09:45:52PM +0000, Nicolas Pitre wrote:
> On Mon, 17 Dec 2012, Will Deacon wrote:
> > This patch adds support for SMP to mach-virt using the PSCI
> > infrastructure.
> > 
> > Signed-off-by: Will Deacon <will.deacon@arm.com>

[...]

> > +/*
> > + * Enumerate the possible CPU set from the device tree.
> > + */
> > +static void __init virt_smp_init_cpus(void)
> > +{
> > +	struct device_node *dn = NULL;
> > +	int cpu = 0;
> > +
> > +	while ((dn = of_find_node_by_type(dn, "cpu"))) {
> > +		if (cpu < NR_CPUS)
> > +			set_cpu_possible(cpu, true);
> > +		cpu++;
> > +	}
> > +
> > +	/* sanity check */
> > +	if (cpu > NR_CPUS)
> > +		pr_warning("no. of cores (%d) greater than configured maximum "
> > +			   "of %d - clipping\n",
> > +			   cpu, NR_CPUS);
> 
> Since commit 5587164eea you shouldn't need any of the above.

There's going to be nothing left at this rate! Thanks.

> > +#ifdef CONFIG_SMP
> > +extern struct smp_operations virt_smp_ops;
> > +#endif
> 
> You don't need to surround prototype declaration here, unless your goal 
> was to define a dummy virt_smp_ops when CONFIG_SMP is not selected?
> Otherwise the reference below would break compilation.

Right you are, the smp_ops macro does the magic for us. I'll put together a
v3.

Cheers,

Will

> > +
> >  DT_MACHINE_START(VIRT, "Dummy Virtual Machine")
> >  	.init_irq	= gic_init_irq,
> >  	.handle_irq     = gic_handle_irq,
> >  	.timer		= &virt_timer,
> >  	.init_machine	= virt_init,
> > +	.smp		= smp_ops(virt_smp_ops),
> >  	.dt_compat	= virt_dt_match,
> >  MACHINE_END
> > -- 
> > 1.8.0
> > 
>
Stefano Stabellini Dec. 18, 2012, 12:19 p.m. UTC | #3
On Mon, 17 Dec 2012, Will Deacon wrote:
> This patch adds support for SMP to mach-virt using the PSCI
> infrastructure.
> 
> Signed-off-by: Will Deacon <will.deacon@arm.com>
>
>  arch/arm/mach-virt/Kconfig   |  1 +
>  arch/arm/mach-virt/Makefile  |  1 +
>  arch/arm/mach-virt/platsmp.c | 76 ++++++++++++++++++++++++++++++++++++++++++++
>  arch/arm/mach-virt/virt.c    |  6 ++++
>  4 files changed, 84 insertions(+)
>  create mode 100644 arch/arm/mach-virt/platsmp.c
> 
> diff --git a/arch/arm/mach-virt/Kconfig b/arch/arm/mach-virt/Kconfig
> index a568a2a..8958f0d 100644
> --- a/arch/arm/mach-virt/Kconfig
> +++ b/arch/arm/mach-virt/Kconfig
> @@ -3,6 +3,7 @@ config ARCH_VIRT
>  	select ARCH_WANT_OPTIONAL_GPIOLIB
>  	select ARM_GIC
>  	select ARM_ARCH_TIMER
> +	select ARM_PSCI
>  	select HAVE_SMP
>  	select CPU_V7
>  	select SPARSE_IRQ

Considering that PSCI is actually needed only to boot secondary cpus,
maybe we want to select it if CONFIG_SMP is enabled?


> diff --git a/arch/arm/mach-virt/Makefile b/arch/arm/mach-virt/Makefile
> index 7ddbfa6..042afc1 100644
> --- a/arch/arm/mach-virt/Makefile
> +++ b/arch/arm/mach-virt/Makefile
> @@ -3,3 +3,4 @@
>  #
>  
>  obj-y					:= virt.o
> +obj-$(CONFIG_SMP)			+= platsmp.o
> diff --git a/arch/arm/mach-virt/platsmp.c b/arch/arm/mach-virt/platsmp.c
> new file mode 100644
> index 0000000..930362b
> --- /dev/null
> +++ b/arch/arm/mach-virt/platsmp.c
> @@ -0,0 +1,76 @@
> +/*
> + * Dummy Virtual Machine - does what it says on the tin.
> + *
> + * Copyright (C) 2012 ARM Ltd
> + * Author: Will Deacon <will.deacon@arm.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/smp.h>
> +#include <linux/of.h>
> +
> +#include <asm/psci.h>
> +#include <asm/smp_plat.h>
> +#include <asm/hardware/gic.h>
> +
> +extern void secondary_startup(void);
> +
> +/*
> + * Enumerate the possible CPU set from the device tree.
> + */
> +static void __init virt_smp_init_cpus(void)
> +{
> +	struct device_node *dn = NULL;
> +	int cpu = 0;
> +
> +	while ((dn = of_find_node_by_type(dn, "cpu"))) {
> +		if (cpu < NR_CPUS)
> +			set_cpu_possible(cpu, true);
> +		cpu++;
> +	}
> +
> +	/* sanity check */
> +	if (cpu > NR_CPUS)
> +		pr_warning("no. of cores (%d) greater than configured maximum "
> +			   "of %d - clipping\n",
> +			   cpu, NR_CPUS);
> +
> +	set_smp_cross_call(gic_raise_softirq);
> +}
> +
> +static void __init virt_smp_prepare_cpus(unsigned int max_cpus)
> +{
> +}
> +
> +static int __cpuinit virt_boot_secondary(unsigned int cpu,
> +					 struct task_struct *idle)
> +{
> +	if (psci_ops.cpu_on)
> +		return psci_ops.cpu_on(cpu_logical_map(cpu),
> +				       __pa(secondary_startup));
> +	return -ENODEV;
> +}

Isn't there a better way to check whether PSCI is actually "enabled", as
in present in the device tree and initialized correctly?

Maybe we need a pcsi_enabled() static inline of some sort?


> +static void __cpuinit virt_secondary_init(unsigned int cpu)
> +{
> +	gic_secondary_init(0);
> +}
> +
> +struct smp_operations __initdata virt_smp_ops = {
> +	.smp_init_cpus		= virt_smp_init_cpus,
> +	.smp_prepare_cpus	= virt_smp_prepare_cpus,
> +	.smp_secondary_init	= virt_secondary_init,
> +	.smp_boot_secondary	= virt_boot_secondary,
> +};
> diff --git a/arch/arm/mach-virt/virt.c b/arch/arm/mach-virt/virt.c
> index 174b9da..d764835 100644
> --- a/arch/arm/mach-virt/virt.c
> +++ b/arch/arm/mach-virt/virt.c
> @@ -20,6 +20,7 @@
>  
>  #include <linux/of_irq.h>
>  #include <linux/of_platform.h>
> +#include <linux/smp.h>
>  
>  #include <asm/arch_timer.h>
>  #include <asm/hardware/gic.h>
> @@ -56,10 +57,15 @@ static struct sys_timer virt_timer = {
>  	.init = virt_timer_init,
>  };
>  
> +#ifdef CONFIG_SMP
> +extern struct smp_operations virt_smp_ops;
> +#endif
> +
>  DT_MACHINE_START(VIRT, "Dummy Virtual Machine")
>  	.init_irq	= gic_init_irq,
>  	.handle_irq     = gic_handle_irq,
>  	.timer		= &virt_timer,
>  	.init_machine	= virt_init,
> +	.smp		= smp_ops(virt_smp_ops),
>  	.dt_compat	= virt_dt_match,
>  MACHINE_END
> -- 
> 1.8.0
Marc Zyngier Dec. 18, 2012, 1:12 p.m. UTC | #4
On 18/12/12 12:19, Stefano Stabellini wrote:
> On Mon, 17 Dec 2012, Will Deacon wrote:
>> This patch adds support for SMP to mach-virt using the PSCI
>> infrastructure.
>>
>> Signed-off-by: Will Deacon <will.deacon@arm.com>
>>
>>  arch/arm/mach-virt/Kconfig   |  1 +
>>  arch/arm/mach-virt/Makefile  |  1 +
>>  arch/arm/mach-virt/platsmp.c | 76 ++++++++++++++++++++++++++++++++++++++++++++
>>  arch/arm/mach-virt/virt.c    |  6 ++++
>>  4 files changed, 84 insertions(+)
>>  create mode 100644 arch/arm/mach-virt/platsmp.c
>>
>> diff --git a/arch/arm/mach-virt/Kconfig b/arch/arm/mach-virt/Kconfig
>> index a568a2a..8958f0d 100644
>> --- a/arch/arm/mach-virt/Kconfig
>> +++ b/arch/arm/mach-virt/Kconfig
>> @@ -3,6 +3,7 @@ config ARCH_VIRT
>>  	select ARCH_WANT_OPTIONAL_GPIOLIB
>>  	select ARM_GIC
>>  	select ARM_ARCH_TIMER
>> +	select ARM_PSCI
>>  	select HAVE_SMP
>>  	select CPU_V7
>>  	select SPARSE_IRQ
> 
> Considering that PSCI is actually needed only to boot secondary cpus,
> maybe we want to select it if CONFIG_SMP is enabled?

Well, I was considering using it to "power-off" the VM when the last CPU
powers itself off, and this would apply to UP as well.

>> diff --git a/arch/arm/mach-virt/Makefile b/arch/arm/mach-virt/Makefile
>> index 7ddbfa6..042afc1 100644
>> --- a/arch/arm/mach-virt/Makefile
>> +++ b/arch/arm/mach-virt/Makefile
>> @@ -3,3 +3,4 @@
>>  #
>>  
>>  obj-y					:= virt.o
>> +obj-$(CONFIG_SMP)			+= platsmp.o
>> diff --git a/arch/arm/mach-virt/platsmp.c b/arch/arm/mach-virt/platsmp.c
>> new file mode 100644
>> index 0000000..930362b
>> --- /dev/null
>> +++ b/arch/arm/mach-virt/platsmp.c
>> @@ -0,0 +1,76 @@
>> +/*
>> + * Dummy Virtual Machine - does what it says on the tin.
>> + *
>> + * Copyright (C) 2012 ARM Ltd
>> + * Author: Will Deacon <will.deacon@arm.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/init.h>
>> +#include <linux/smp.h>
>> +#include <linux/of.h>
>> +
>> +#include <asm/psci.h>
>> +#include <asm/smp_plat.h>
>> +#include <asm/hardware/gic.h>
>> +
>> +extern void secondary_startup(void);
>> +
>> +/*
>> + * Enumerate the possible CPU set from the device tree.
>> + */
>> +static void __init virt_smp_init_cpus(void)
>> +{
>> +	struct device_node *dn = NULL;
>> +	int cpu = 0;
>> +
>> +	while ((dn = of_find_node_by_type(dn, "cpu"))) {
>> +		if (cpu < NR_CPUS)
>> +			set_cpu_possible(cpu, true);
>> +		cpu++;
>> +	}
>> +
>> +	/* sanity check */
>> +	if (cpu > NR_CPUS)
>> +		pr_warning("no. of cores (%d) greater than configured maximum "
>> +			   "of %d - clipping\n",
>> +			   cpu, NR_CPUS);
>> +
>> +	set_smp_cross_call(gic_raise_softirq);
>> +}
>> +
>> +static void __init virt_smp_prepare_cpus(unsigned int max_cpus)
>> +{
>> +}
>> +
>> +static int __cpuinit virt_boot_secondary(unsigned int cpu,
>> +					 struct task_struct *idle)
>> +{
>> +	if (psci_ops.cpu_on)
>> +		return psci_ops.cpu_on(cpu_logical_map(cpu),
>> +				       __pa(secondary_startup));
>> +	return -ENODEV;
>> +}
> 
> Isn't there a better way to check whether PSCI is actually "enabled", as
> in present in the device tree and initialized correctly?

All methods are optional, so I'm afraid you have to check for their
validity each time you want to access one.

> Maybe we need a pcsi_enabled() static inline of some sort?
> 
> 
>> +static void __cpuinit virt_secondary_init(unsigned int cpu)
>> +{
>> +	gic_secondary_init(0);
>> +}
>> +
>> +struct smp_operations __initdata virt_smp_ops = {
>> +	.smp_init_cpus		= virt_smp_init_cpus,
>> +	.smp_prepare_cpus	= virt_smp_prepare_cpus,
>> +	.smp_secondary_init	= virt_secondary_init,
>> +	.smp_boot_secondary	= virt_boot_secondary,
>> +};
>> diff --git a/arch/arm/mach-virt/virt.c b/arch/arm/mach-virt/virt.c
>> index 174b9da..d764835 100644
>> --- a/arch/arm/mach-virt/virt.c
>> +++ b/arch/arm/mach-virt/virt.c
>> @@ -20,6 +20,7 @@
>>  
>>  #include <linux/of_irq.h>
>>  #include <linux/of_platform.h>
>> +#include <linux/smp.h>
>>  
>>  #include <asm/arch_timer.h>
>>  #include <asm/hardware/gic.h>
>> @@ -56,10 +57,15 @@ static struct sys_timer virt_timer = {
>>  	.init = virt_timer_init,
>>  };
>>  
>> +#ifdef CONFIG_SMP
>> +extern struct smp_operations virt_smp_ops;
>> +#endif
>> +
>>  DT_MACHINE_START(VIRT, "Dummy Virtual Machine")
>>  	.init_irq	= gic_init_irq,
>>  	.handle_irq     = gic_handle_irq,
>>  	.timer		= &virt_timer,
>>  	.init_machine	= virt_init,
>> +	.smp		= smp_ops(virt_smp_ops),
>>  	.dt_compat	= virt_dt_match,
>>  MACHINE_END
>> -- 
>> 1.8.0
>
diff mbox

Patch

diff --git a/arch/arm/mach-virt/Kconfig b/arch/arm/mach-virt/Kconfig
index a568a2a..8958f0d 100644
--- a/arch/arm/mach-virt/Kconfig
+++ b/arch/arm/mach-virt/Kconfig
@@ -3,6 +3,7 @@  config ARCH_VIRT
 	select ARCH_WANT_OPTIONAL_GPIOLIB
 	select ARM_GIC
 	select ARM_ARCH_TIMER
+	select ARM_PSCI
 	select HAVE_SMP
 	select CPU_V7
 	select SPARSE_IRQ
diff --git a/arch/arm/mach-virt/Makefile b/arch/arm/mach-virt/Makefile
index 7ddbfa6..042afc1 100644
--- a/arch/arm/mach-virt/Makefile
+++ b/arch/arm/mach-virt/Makefile
@@ -3,3 +3,4 @@ 
 #
 
 obj-y					:= virt.o
+obj-$(CONFIG_SMP)			+= platsmp.o
diff --git a/arch/arm/mach-virt/platsmp.c b/arch/arm/mach-virt/platsmp.c
new file mode 100644
index 0000000..930362b
--- /dev/null
+++ b/arch/arm/mach-virt/platsmp.c
@@ -0,0 +1,76 @@ 
+/*
+ * Dummy Virtual Machine - does what it says on the tin.
+ *
+ * Copyright (C) 2012 ARM Ltd
+ * Author: Will Deacon <will.deacon@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/of.h>
+
+#include <asm/psci.h>
+#include <asm/smp_plat.h>
+#include <asm/hardware/gic.h>
+
+extern void secondary_startup(void);
+
+/*
+ * Enumerate the possible CPU set from the device tree.
+ */
+static void __init virt_smp_init_cpus(void)
+{
+	struct device_node *dn = NULL;
+	int cpu = 0;
+
+	while ((dn = of_find_node_by_type(dn, "cpu"))) {
+		if (cpu < NR_CPUS)
+			set_cpu_possible(cpu, true);
+		cpu++;
+	}
+
+	/* sanity check */
+	if (cpu > NR_CPUS)
+		pr_warning("no. of cores (%d) greater than configured maximum "
+			   "of %d - clipping\n",
+			   cpu, NR_CPUS);
+
+	set_smp_cross_call(gic_raise_softirq);
+}
+
+static void __init virt_smp_prepare_cpus(unsigned int max_cpus)
+{
+}
+
+static int __cpuinit virt_boot_secondary(unsigned int cpu,
+					 struct task_struct *idle)
+{
+	if (psci_ops.cpu_on)
+		return psci_ops.cpu_on(cpu_logical_map(cpu),
+				       __pa(secondary_startup));
+	return -ENODEV;
+}
+
+static void __cpuinit virt_secondary_init(unsigned int cpu)
+{
+	gic_secondary_init(0);
+}
+
+struct smp_operations __initdata virt_smp_ops = {
+	.smp_init_cpus		= virt_smp_init_cpus,
+	.smp_prepare_cpus	= virt_smp_prepare_cpus,
+	.smp_secondary_init	= virt_secondary_init,
+	.smp_boot_secondary	= virt_boot_secondary,
+};
diff --git a/arch/arm/mach-virt/virt.c b/arch/arm/mach-virt/virt.c
index 174b9da..d764835 100644
--- a/arch/arm/mach-virt/virt.c
+++ b/arch/arm/mach-virt/virt.c
@@ -20,6 +20,7 @@ 
 
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
+#include <linux/smp.h>
 
 #include <asm/arch_timer.h>
 #include <asm/hardware/gic.h>
@@ -56,10 +57,15 @@  static struct sys_timer virt_timer = {
 	.init = virt_timer_init,
 };
 
+#ifdef CONFIG_SMP
+extern struct smp_operations virt_smp_ops;
+#endif
+
 DT_MACHINE_START(VIRT, "Dummy Virtual Machine")
 	.init_irq	= gic_init_irq,
 	.handle_irq     = gic_handle_irq,
 	.timer		= &virt_timer,
 	.init_machine	= virt_init,
+	.smp		= smp_ops(virt_smp_ops),
 	.dt_compat	= virt_dt_match,
 MACHINE_END