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: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Feng Wu <feng.wu@intel.com>
Link: http://lkml.kernel.org/r/1432026437-16560-2-git-send-email-feng.wu@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Jiang Liu 2015-05-19 17:07:14 +08:00 committed by Thomas Gleixner
parent 5ebe6afaf0
commit 0a4377de30
3 changed files with 51 additions and 0 deletions

View File

@ -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: */

View File

@ -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

View File

@ -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 =