From 0a4377de305684c883bf90ad21e3cbdeead70f5c Mon Sep 17 00:00:00 2001 From: Jiang Liu Date: Tue, 19 May 2015 17:07:14 +0800 Subject: [PATCH] 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 Signed-off-by: Feng Wu Link: http://lkml.kernel.org/r/1432026437-16560-2-git-send-email-feng.wu@intel.com Signed-off-by: Thomas Gleixner --- include/linux/irq.h | 6 ++++++ kernel/irq/chip.c | 14 ++++++++++++++ kernel/irq/manage.c | 31 +++++++++++++++++++++++++++++++ 3 files changed, 51 insertions(+) diff --git a/include/linux/irq.h b/include/linux/irq.h index 62c6901cab55..48cb7d1aa58f 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -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: */ diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index eb9a4ea394ab..55016b2151f3 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -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 diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index e68932bb308e..b1c7e8f46bfb 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -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 =