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authorSasha Levin <levinsasha928@gmail.com>2011-07-27 16:00:48 +0300
committerAvi Kivity <avi@redhat.com>2011-09-25 19:17:59 +0300
commit743eeb0b01d2fbf4154bf87bff1ebb6fb18aeb7a (patch)
tree5392464930f7e77131d65f32ba96ce4665307629 /arch/x86
parent0d460ffc0956d2dbe12ca9f5f6aa0f8701ea9d73 (diff)
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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 <avi@redhat.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kvm/i8254.c6
-rw-r--r--arch/x86/kvm/i8259.c108
-rw-r--r--arch/x86/kvm/irq.h4
-rw-r--r--arch/x86/kvm/x86.c6
4 files changed, 101 insertions, 23 deletions
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;