From f848a5a8dcb655553423f77cc98909a04e64173d Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Mon, 31 Mar 2014 21:50:38 +0300 Subject: KVM: support any-length wildcard ioeventfd It is sometimes benefitial to ignore IO size, and only match on address. In hindsight this would have been a better default than matching length when KVM_IOEVENTFD_FLAG_DATAMATCH is not set, In particular, this kind of access can be optimized on VMX: there no need to do page lookups. This can currently be done with many ioeventfds but in a suboptimal way. However we can't change kernel/userspace ABI without risk of breaking some applications. Use len = 0 to mean "ignore length for matching" in a more optimal way. Signed-off-by: Michael S. Tsirkin Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/x86.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/kvm/x86.c') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8b8fc0b792ba..bc4aaf68190c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2644,6 +2644,7 @@ int kvm_dev_ioctl_check_extension(long ext) case KVM_CAP_IRQ_INJECT_STATUS: case KVM_CAP_IRQFD: case KVM_CAP_IOEVENTFD: + case KVM_CAP_IOEVENTFD_NO_LENGTH: case KVM_CAP_PIT2: case KVM_CAP_PIT_STATE2: case KVM_CAP_SET_IDENTITY_MAP_ADDR: -- cgit v1.2.3