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-rw-r--r--Documentation/virtual/kvm/api.txt16
-rw-r--r--include/uapi/linux/kvm.h11
-rw-r--r--virt/kvm/coalesced_mmio.c12
-rw-r--r--virt/kvm/kvm_main.c2
4 files changed, 30 insertions, 11 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 10d48eb67da9..70f9c8bb1840 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3683,27 +3683,31 @@ the definition of struct kvm_nested_state, see KVM_GET_NESTED_STATE.
4.116 KVM_(UN)REGISTER_COALESCED_MMIO
-Capability: KVM_CAP_COALESCED_MMIO
+Capability: KVM_CAP_COALESCED_MMIO (for coalesced mmio)
+ KVM_CAP_COALESCED_PIO (for coalesced pio)
Architectures: all
Type: vm ioctl
Parameters: struct kvm_coalesced_mmio_zone
Returns: 0 on success, < 0 on error
-Coalesced mmio is a performance optimization that defers hardware
+Coalesced I/O is a performance optimization that defers hardware
register write emulation so that userspace exits are avoided. It is
typically used to reduce the overhead of emulating frequently accessed
hardware registers.
-When a hardware register is configured for coalesced mmio, write accesses
+When a hardware register is configured for coalesced I/O, write accesses
do not exit to userspace and their value is recorded in a ring buffer
that is shared between kernel and userspace.
-Coalesced mmio is used if one or more write accesses to a hardware
+Coalesced I/O is used if one or more write accesses to a hardware
register can be deferred until a read or a write to another hardware
register on the same device. This last access will cause a vmexit and
userspace will process accesses from the ring buffer before emulating
-it. That will avoid exiting to userspace on repeated writes to the
-first register.
+it. That will avoid exiting to userspace on repeated writes.
+
+Coalesced pio is based on coalesced mmio. There is little difference
+between coalesced mmio and pio except that coalesced pio records accesses
+to I/O ports.
5. The kvm_run structure
------------------------
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 7785678caedb..97780a0277fe 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -420,13 +420,19 @@ struct kvm_run {
struct kvm_coalesced_mmio_zone {
__u64 addr;
__u32 size;
- __u32 pad;
+ union {
+ __u32 pad;
+ __u32 pio;
+ };
};
struct kvm_coalesced_mmio {
__u64 phys_addr;
__u32 len;
- __u32 pad;
+ union {
+ __u32 pad;
+ __u32 pio;
+ };
__u8 data[8];
};
@@ -956,6 +962,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_MSR_PLATFORM_INFO 159
#define KVM_CAP_PPC_NESTED_HV 160
#define KVM_CAP_HYPERV_SEND_IPI 161
+#define KVM_CAP_COALESCED_PIO 162
#ifdef KVM_CAP_IRQ_ROUTING
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index 9e65feb6fa58..3710342cf6ad 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -83,6 +83,7 @@ static int coalesced_mmio_write(struct kvm_vcpu *vcpu,
ring->coalesced_mmio[ring->last].phys_addr = addr;
ring->coalesced_mmio[ring->last].len = len;
memcpy(ring->coalesced_mmio[ring->last].data, val, len);
+ ring->coalesced_mmio[ring->last].pio = dev->zone.pio;
smp_wmb();
ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
spin_unlock(&dev->kvm->ring_lock);
@@ -140,6 +141,9 @@ int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
int ret;
struct kvm_coalesced_mmio_dev *dev;
+ if (zone->pio != 1 && zone->pio != 0)
+ return -EINVAL;
+
dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
if (!dev)
return -ENOMEM;
@@ -149,8 +153,9 @@ int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
dev->zone = *zone;
mutex_lock(&kvm->slots_lock);
- ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, zone->addr,
- zone->size, &dev->dev);
+ ret = kvm_io_bus_register_dev(kvm,
+ zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS,
+ zone->addr, zone->size, &dev->dev);
if (ret < 0)
goto out_free_dev;
list_add_tail(&dev->list, &kvm->coalesced_zones);
@@ -174,7 +179,8 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list)
if (coalesced_mmio_in_range(dev, zone->addr, zone->size)) {
- kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &dev->dev);
+ kvm_io_bus_unregister_dev(kvm,
+ zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev);
kvm_iodevice_destructor(&dev->dev);
}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index acc951cc2663..067b71abae00 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2949,6 +2949,8 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
#ifdef CONFIG_KVM_MMIO
case KVM_CAP_COALESCED_MMIO:
return KVM_COALESCED_MMIO_PAGE_OFFSET;
+ case KVM_CAP_COALESCED_PIO:
+ return 1;
#endif
#ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
case KVM_CAP_IRQ_ROUTING: