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. We may also cooperate between set_affinity() and set_vcpu_affinity() in IRQ core or irq chip drivers. Here is the usage scenario for this interface: Guest update MSI/MSI-X interrupt configuratoin -->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) You can find the VT-d Posted-Interrtups Spec. in the following URL: http://www.intel.com/content/www/us/en/intelligent-systems/intel-technology/vt-directed-io-spec.html Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx> Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx> --- include/linux/irq.h | 6 ++++++ kernel/irq/manage.c | 19 +++++++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/include/linux/irq.h b/include/linux/irq.h index 8badf34baf0f..0a3c8ac38ffb 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -29,6 +29,7 @@ struct seq_file; struct module; struct msi_msg; +struct irq_vcpu_id; /* * IRQ line status. @@ -323,6 +324,8 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d) * irq_request_resources * @irq_compose_msi_msg: optional to compose message content for MSI * @irq_write_msi_msg: optional to write message content for MSI + * @irq_set_vcpu_affinity: optional to target a virtual CPU in a virtual + * machine * @flags: chip specific flags */ struct irq_chip { @@ -362,6 +365,8 @@ struct irq_chip { void (*irq_compose_msi_msg)(struct irq_data *data, struct msi_msg *msg); void (*irq_write_msi_msg)(struct irq_data *data, struct msi_msg *msg); + int (*irq_set_vcpu_affinity)(struct irq_data *data, struct irq_vcpu_id *vcpu_id); + unsigned long flags; }; @@ -415,6 +420,7 @@ 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, struct irq_vcpu_id *vcpu_id); #if defined(CONFIG_SMP) && defined(CONFIG_GENERIC_PENDING_IRQ) void irq_move_irq(struct irq_data *data); diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 80692373abd6..4ae8f243293a 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -247,6 +247,25 @@ int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m) } EXPORT_SYMBOL_GPL(irq_set_affinity_hint); +int irq_set_vcpu_affinity(unsigned int irq, struct irq_vcpu_id *vcpu_id) +{ + struct irq_desc *desc = irq_to_desc(irq); + struct irq_chip *chip; + unsigned long flags; + int ret = -ENOSYS; + + if (!desc) + return -EINVAL; + + raw_spin_lock_irqsave(&desc->lock, flags); + chip = desc->irq_data.chip; + if (chip && chip->irq_set_vcpu_affinity) + ret = chip->irq_set_vcpu_affinity(&desc->irq_data, vcpu_id); + raw_spin_unlock_irqrestore(&desc->lock, flags); + + return ret; +} + static void irq_affinity_notify(struct work_struct *work) { struct irq_affinity_notify *notify = -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
