Cc: Gleb Natapov <gleb@xxxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx> --- Documentation/virtual/kvm/api.txt | 7 ++++++- include/uapi/linux/kvm.h | 1 + virt/kvm/kvm_main.c | 1 + 3 files changed, 8 insertions(+), 1 deletion(-) diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index d9eccee..26661ef 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1598,7 +1598,7 @@ 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]; @@ -1621,6 +1621,11 @@ 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_FAST_MMIO, a zero length mmio eventfd is allowed for +kernel to ignore the length of guest write and get a possible faster +response. Note the speedup may only work on some specific +architectures and setups. Otherwise, it's as fast as wildcard mmio +eventfd. 4.60 KVM_DIRTY_TLB diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index a9256f0..ad72a61 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -824,6 +824,7 @@ struct kvm_ppc_smmu_info { #define KVM_CAP_MULTI_ADDRESS_SPACE 118 #define KVM_CAP_GUEST_DEBUG_HW_BPS 119 #define KVM_CAP_GUEST_DEBUG_HW_WPS 120 +#define KVM_CAP_FAST_MMIO 121 #ifdef KVM_CAP_IRQ_ROUTING diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 9af68db..645f55d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2717,6 +2717,7 @@ 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_FAST_MMIO: case KVM_CAP_CHECK_EXTENSION_VM: return 1; #ifdef CONFIG_HAVE_KVM_IRQ_ROUTING -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html