diff options
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 16 | ||||
| -rw-r--r-- | include/uapi/linux/kvm.h | 11 | ||||
| -rw-r--r-- | virt/kvm/coalesced_mmio.c | 12 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 2 |
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: |