From 743eeb0b01d2fbf4154bf87bff1ebb6fb18aeb7a Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Wed, 27 Jul 2011 16:00:48 +0300 Subject: KVM: Intelligent device lookup on I/O bus Currently the method of dealing with an IO operation on a bus (PIO/MMIO) is to call the read or write callback for each device registered on the bus until we find a device which handles it. Since the number of devices on a bus can be significant due to ioeventfds and coalesced MMIO zones, this leads to a lot of overhead on each IO operation. Instead of registering devices, we now register ranges which points to a device. Lookup is done using an efficient bsearch instead of a linear search. Performance test was conducted by comparing exit count per second with 200 ioeventfds created on one byte and the guest is trying to access a different byte continuously (triggering usermode exits). Before the patch the guest has achieved 259k exits per second, after the patch the guest does 274k exits per second. Cc: Avi Kivity Cc: Marcelo Tosatti Signed-off-by: Sasha Levin Signed-off-by: Avi Kivity --- arch/x86/kvm/i8254.c | 6 ++- arch/x86/kvm/i8259.c | 108 ++++++++++++++++++++++++++++++++++++++++++--------- arch/x86/kvm/irq.h | 4 +- arch/x86/kvm/x86.c | 6 ++- 4 files changed, 101 insertions(+), 23 deletions(-) (limited to 'arch/x86/kvm') diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index efad72385058..76e3f1cd0369 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -713,14 +713,16 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags) kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier); kvm_iodevice_init(&pit->dev, &pit_dev_ops); - ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, &pit->dev); + ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS, + KVM_PIT_MEM_LENGTH, &pit->dev); if (ret < 0) goto fail; if (flags & KVM_PIT_SPEAKER_DUMMY) { kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops); ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, - &pit->speaker_dev); + KVM_SPEAKER_BASE_ADDRESS, 4, + &pit->speaker_dev); if (ret < 0) goto fail_unregister; } diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c index 19fe855e7953..6b869ce0cc19 100644 --- a/arch/x86/kvm/i8259.c +++ b/arch/x86/kvm/i8259.c @@ -459,15 +459,9 @@ static int picdev_in_range(gpa_t addr) } } -static inline struct kvm_pic *to_pic(struct kvm_io_device *dev) -{ - return container_of(dev, struct kvm_pic, dev); -} - -static int picdev_write(struct kvm_io_device *this, +static int picdev_write(struct kvm_pic *s, gpa_t addr, int len, const void *val) { - struct kvm_pic *s = to_pic(this); unsigned char data = *(unsigned char *)val; if (!picdev_in_range(addr)) return -EOPNOTSUPP; @@ -494,10 +488,9 @@ static int picdev_write(struct kvm_io_device *this, return 0; } -static int picdev_read(struct kvm_io_device *this, +static int picdev_read(struct kvm_pic *s, gpa_t addr, int len, void *val) { - struct kvm_pic *s = to_pic(this); unsigned char data = 0; if (!picdev_in_range(addr)) return -EOPNOTSUPP; @@ -525,6 +518,48 @@ static int picdev_read(struct kvm_io_device *this, return 0; } +static int picdev_master_write(struct kvm_io_device *dev, + gpa_t addr, int len, const void *val) +{ + return picdev_write(container_of(dev, struct kvm_pic, dev_master), + addr, len, val); +} + +static int picdev_master_read(struct kvm_io_device *dev, + gpa_t addr, int len, void *val) +{ + return picdev_read(container_of(dev, struct kvm_pic, dev_master), + addr, len, val); +} + +static int picdev_slave_write(struct kvm_io_device *dev, + gpa_t addr, int len, const void *val) +{ + return picdev_write(container_of(dev, struct kvm_pic, dev_slave), + addr, len, val); +} + +static int picdev_slave_read(struct kvm_io_device *dev, + gpa_t addr, int len, void *val) +{ + return picdev_read(container_of(dev, struct kvm_pic, dev_slave), + addr, len, val); +} + +static int picdev_eclr_write(struct kvm_io_device *dev, + gpa_t addr, int len, const void *val) +{ + return picdev_write(container_of(dev, struct kvm_pic, dev_eclr), + addr, len, val); +} + +static int picdev_eclr_read(struct kvm_io_device *dev, + gpa_t addr, int len, void *val) +{ + return picdev_read(container_of(dev, struct kvm_pic, dev_eclr), + addr, len, val); +} + /* * callback when PIC0 irq status changed */ @@ -537,9 +572,19 @@ static void pic_irq_request(struct kvm *kvm, int level) s->output = level; } -static const struct kvm_io_device_ops picdev_ops = { - .read = picdev_read, - .write = picdev_write, +static const struct kvm_io_device_ops picdev_master_ops = { + .read = picdev_master_read, + .write = picdev_master_write, +}; + +static const struct kvm_io_device_ops picdev_slave_ops = { + .read = picdev_slave_read, + .write = picdev_slave_write, +}; + +static const struct kvm_io_device_ops picdev_eclr_ops = { + .read = picdev_eclr_read, + .write = picdev_eclr_write, }; struct kvm_pic *kvm_create_pic(struct kvm *kvm) @@ -560,16 +605,39 @@ struct kvm_pic *kvm_create_pic(struct kvm *kvm) /* * Initialize PIO device */ - kvm_iodevice_init(&s->dev, &picdev_ops); + kvm_iodevice_init(&s->dev_master, &picdev_master_ops); + kvm_iodevice_init(&s->dev_slave, &picdev_slave_ops); + kvm_iodevice_init(&s->dev_eclr, &picdev_eclr_ops); mutex_lock(&kvm->slots_lock); - ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, &s->dev); + ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x20, 2, + &s->dev_master); + if (ret < 0) + goto fail_unlock; + + ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0xa0, 2, &s->dev_slave); + if (ret < 0) + goto fail_unreg_2; + + ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x4d0, 2, &s->dev_eclr); + if (ret < 0) + goto fail_unreg_1; + mutex_unlock(&kvm->slots_lock); - if (ret < 0) { - kfree(s); - return NULL; - } return s; + +fail_unreg_1: + kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &s->dev_slave); + +fail_unreg_2: + kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &s->dev_master); + +fail_unlock: + mutex_unlock(&kvm->slots_lock); + + kfree(s); + + return NULL; } void kvm_destroy_pic(struct kvm *kvm) @@ -577,7 +645,9 @@ void kvm_destroy_pic(struct kvm *kvm) struct kvm_pic *vpic = kvm->arch.vpic; if (vpic) { - kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &vpic->dev); + kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &vpic->dev_master); + kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &vpic->dev_slave); + kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &vpic->dev_eclr); kvm->arch.vpic = NULL; kfree(vpic); } diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h index 53e2d084bffb..2086f2bfba33 100644 --- a/arch/x86/kvm/irq.h +++ b/arch/x86/kvm/irq.h @@ -66,7 +66,9 @@ struct kvm_pic { struct kvm *kvm; struct kvm_kpic_state pics[2]; /* 0 is master pic, 1 is slave pic */ int output; /* intr from master PIC */ - struct kvm_io_device dev; + struct kvm_io_device dev_master; + struct kvm_io_device dev_slave; + struct kvm_io_device dev_eclr; void (*ack_notifier)(void *opaque, int irq); unsigned long irq_states[16]; }; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6cb353c83a12..d28dff749dfd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3562,7 +3562,11 @@ long kvm_arch_vm_ioctl(struct file *filp, if (r) { mutex_lock(&kvm->slots_lock); kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, - &vpic->dev); + &vpic->dev_master); + kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, + &vpic->dev_slave); + kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, + &vpic->dev_eclr); mutex_unlock(&kvm->slots_lock); kfree(vpic); goto create_irqchip_unlock; -- cgit v1.2.3