diff options
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 6 | ||||
| -rw-r--r-- | include/uapi/linux/kvm.h | 1 | ||||
| -rw-r--r-- | virt/kvm/eventfd.c | 4 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 1 |
4 files changed, 8 insertions, 4 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index e3e9c41721a2..34cc068e81ea 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1604,7 +1604,7 @@ provided event instead of triggering an exit. struct kvm_ioeventfd { __u64 datamatch; __u64 addr; /* legal pio/mmio address */ - __u32 len; /* 1, 2, 4, or 8 bytes */ + __u32 len; /* 0, 1, 2, 4, or 8 bytes */ __s32 fd; __u32 flags; __u8 pad[36]; @@ -1627,6 +1627,10 @@ to the registered address is equal to datamatch in struct kvm_ioeventfd. For virtio-ccw devices, addr contains the subchannel id and datamatch the virtqueue index. +With KVM_CAP_IOEVENTFD_ANY_LENGTH, a zero length ioeventfd is allowed, and +the kernel will ignore the length of guest write and may get a faster vmexit. +The speedup may only apply to specific architectures, but the ioeventfd will +work anyway. 4.60 KVM_DIRTY_TLB diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 12e3afbf0f47..03f3618612aa 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -830,6 +830,7 @@ struct kvm_ppc_smmu_info { #define KVM_CAP_GUEST_DEBUG_HW_BPS 119 #define KVM_CAP_GUEST_DEBUG_HW_WPS 120 #define KVM_CAP_SPLIT_IRQCHIP 121 +#define KVM_CAP_IOEVENTFD_ANY_LENGTH 122 #ifdef KVM_CAP_IRQ_ROUTING diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 79db45336e3a..ac89299b8699 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -914,9 +914,7 @@ kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) return -EINVAL; /* ioeventfd with no length can't be combined with DATAMATCH */ - if (!args->len && - args->flags & (KVM_IOEVENTFD_FLAG_PIO | - KVM_IOEVENTFD_FLAG_DATAMATCH)) + if (!args->len && (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)) return -EINVAL; ret = kvm_assign_ioeventfd_idx(kvm, bus_idx, args); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 23116dcb2129..afd7ae6aec65 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2718,6 +2718,7 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) case KVM_CAP_IRQFD: case KVM_CAP_IRQFD_RESAMPLE: #endif + case KVM_CAP_IOEVENTFD_ANY_LENGTH: case KVM_CAP_CHECK_EXTENSION_VM: return 1; #ifdef CONFIG_HAVE_KVM_IRQ_ROUTING |