Commit 0a4377de authored by Jiang Liu's avatar Jiang Liu Committed by Thomas Gleixner
Browse files

genirq: Introduce irq_set_vcpu_affinity() to target an interrupt to a VCPU 



With Posted-Interrupts support in Intel CPU and IOMMU, an external
interrupt from assigned-devices could be directly delivered to a
virtual CPU in a virtual machine. Instead of hacking KVM and Intel
IOMMU drivers, we propose a platform independent interface to target
an interrupt to a specific virtual CPU in a virtual machine, or set
virtual CPU affinity for an interrupt.

By adopting this new interface and the hierarchy irqdomain, we could
easily support posted-interrupts on Intel platforms, and also provide
flexible enough interfaces for other platforms to support similar
features.

Here is the usage scenario for this interface:
Guest update MSI/MSI-X interrupt configuration
        -->QEMU and KVM handle this
        -->KVM call this interface (passing posted interrupts descriptor
           and guest vector)
        -->irq core will transfer the control to IOMMU
        -->IOMMU will do the real work of updating IRTE (IRTE has new
           format for VT-d Posted-Interrupts)

Signed-off-by: default avatarJiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: default avatarFeng Wu <feng.wu@intel.com>
Link: http://lkml.kernel.org/r/1432026437-16560-2-git-send-email-feng.wu@intel.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 5ebe6afa

include/linux/irq.h

+6 −0
Original line number Diff line number Diff line
@@ -327,6 +327,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d) 
 * @irq_write_msi_msg:	optional to write message content for MSI

 * @irq_get_irqchip_state:	return the internal state of an interrupt

 * @irq_set_irqchip_state:	set the internal state of a interrupt

 * @irq_set_vcpu_affinity:	optional to target a vCPU in a virtual machine

 * @flags:		chip specific flags

 */

struct irq_chip {
@@ -369,6 +370,8 @@ struct irq_chip { 
	int		(*irq_get_irqchip_state)(struct irq_data *data, enum irqchip_irq_state which, bool *state);

	int		(*irq_set_irqchip_state)(struct irq_data *data, enum irqchip_irq_state which, bool state);



	int		(*irq_set_vcpu_affinity)(struct irq_data *data, void *vcpu_info);



	unsigned long	flags;

};
@@ -422,6 +425,7 @@ extern void irq_cpu_online(void); 
extern void irq_cpu_offline(void);

extern int irq_set_affinity_locked(struct irq_data *data,

				   const struct cpumask *cpumask, bool force);

extern int irq_set_vcpu_affinity(unsigned int irq, void *vcpu_info);



#if defined(CONFIG_SMP) && defined(CONFIG_GENERIC_PENDING_IRQ)

void irq_move_irq(struct irq_data *data);
@@ -467,6 +471,8 @@ extern int irq_chip_set_affinity_parent(struct irq_data *data, 
					const struct cpumask *dest,

					bool force);

extern int irq_chip_set_wake_parent(struct irq_data *data, unsigned int on);

extern int irq_chip_set_vcpu_affinity_parent(struct irq_data *data,

					     void *vcpu_info);

#endif



/* Handling of unhandled and spurious interrupts: */

kernel/irq/chip.c

+14 −0
Original line number Diff line number Diff line
@@ -949,6 +949,20 @@ int irq_chip_retrigger_hierarchy(struct irq_data *data) 
	return -ENOSYS;

}



/**

 * irq_chip_set_vcpu_affinity_parent - Set vcpu affinity on the parent interrupt

 * @data:	Pointer to interrupt specific data

 * @dest:	The vcpu affinity information

 */

int irq_chip_set_vcpu_affinity_parent(struct irq_data *data, void *vcpu_info)

{

	data = data->parent_data;

	if (data->chip->irq_set_vcpu_affinity)

		return data->chip->irq_set_vcpu_affinity(data, vcpu_info);



	return -ENOSYS;

}



/**

 * irq_chip_set_wake_parent - Set/reset wake-up on the parent interrupt

 * @data:	Pointer to interrupt specific data

kernel/irq/manage.c

+31 −0
Original line number Diff line number Diff line
@@ -256,6 +256,37 @@ int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m) 
}

EXPORT_SYMBOL_GPL(irq_set_affinity_hint);



/**

 *	irq_set_vcpu_affinity - Set vcpu affinity for the interrupt

 *	@irq: interrupt number to set affinity

 *	@vcpu_info: vCPU specific data

 *

 *	This function uses the vCPU specific data to set the vCPU

 *	affinity for an irq. The vCPU specific data is passed from

 *	outside, such as KVM. One example code path is as below:

 *	KVM -> IOMMU -> irq_set_vcpu_affinity().

 */

int irq_set_vcpu_affinity(unsigned int irq, void *vcpu_info)

{

	unsigned long flags;

	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);

	struct irq_data *data;

	struct irq_chip *chip;

	int ret = -ENOSYS;



	if (!desc)

		return -EINVAL;



	data = irq_desc_get_irq_data(desc);

	chip = irq_data_get_irq_chip(data);

	if (chip && chip->irq_set_vcpu_affinity)

		ret = chip->irq_set_vcpu_affinity(data, vcpu_info);

	irq_put_desc_unlock(desc, flags);



	return ret;

}

EXPORT_SYMBOL_GPL(irq_set_vcpu_affinity);



static void irq_affinity_notify(struct work_struct *work)

{

	struct irq_affinity_notify *notify =

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