This series intends to implement IRQ offloading for vhost_vdpa. By the feat of irq forwarding facilities like posted interrupt on X86, irq bypass can help deliver interrupts to vCPU directly. vDPA devices have dedicated hardware backends like VFIO pass-throughed devices. So it would be possible to setup irq offloading(irq bypass) for vDPA devices and gain performance improvements. In my testing, with this feature, we can save 0.1ms in a ping between two VFs on average. changes from V3: (1)removed vDPA irq allocate/free helpers in vDPA core. (2)add a new function get_vq_irq() in struct vdpa_config_ops, upper layer driver can use this function to: A. query the irq numbner of a vq. B. detect whether a vq is enabled. (3)implement get_vq_irq() in ifcvf driver. (4)in vhost_vdpa, set_status() will setup irq offloading when setting DRIVER_OK, and unsetup when receive !DRIVER_OK. (5)minor improvements. changes from V2: (1)rename struct vhost_call_ctx to vhost_vring_call (2)add kvm_arch_end_assignment() in del_producer() code path (3)rename vDPA helpers to vdpa_devm_request_irq() and vdpa_devm_free_irq(). Add better comments for them. (4)better comments for setup_vq_irq() and unsetup_vq_irq() (5)In vDPA VHOST_SET_VRING_CALL, will call vhost_vdpa_update_vq_irq() without checking producer.irq, move this check into vhost_vdpa_update_vq_irq(), so that get advantage of the spinlock. (6)Add a function vhost_vdpa_clean_irq(), this function will unregister the producer of vqs when vhost_vdpa_release(). This is safe for control vq. (7) minor improvements changes from V1: (1)dropped vfio changes. (3)removed KVM_HVAE_IRQ_BYPASS checks (4)locking fixes (5)simplified vhost_vdpa_updat Zhu Lingshan (6): vhost: introduce vhost_vring_call kvm: detect assigned device via irqbypass manager vDPA: add get_vq_irq() in vdpa_config_ops vhost_vdpa: implement IRQ offloading in vhost_vdpa ifcvf: implement vdpa_config_ops.get_vq_irq() irqbypass: do not start cons/prod when failed connect arch/x86/kvm/x86.c | 12 ++++- drivers/vdpa/ifcvf/ifcvf_main.c | 18 ++++++- drivers/vhost/Kconfig | 1 + drivers/vhost/vdpa.c | 83 +++++++++++++++++++++++++++++++-- drivers/vhost/vhost.c | 22 ++++++--- drivers/vhost/vhost.h | 9 +++- include/linux/vdpa.h | 6 +++ virt/lib/irqbypass.c | 16 ++++--- 8 files changed, 147 insertions(+), 20 deletions(-) -- 2.18.4
