From 8c56c1a592b5092d91da8d8943c17777d6462a6f Mon Sep 17 00:00:00 2001 From: Pavel Fedin Date: Fri, 20 Nov 2015 12:37:16 +0300 Subject: memory: emulate ioeventfd The ioeventfd mechanism is used by vhost, dataplane, and virtio-pci to turn guest MMIO/PIO writes into eventfd file descriptor events. This allows arbitrary threads to be notified when the guest writes to a specific MMIO/PIO address. qtest and TCG do not support ioeventfd because memory writes are not checked against registered ioeventfds in QEMU. This patch implements this in memory_region_dispatch_write() so qtest can use ioeventfd. Also this patch fixes vhost aborting on some misconfigured old kernels like 3.18.0 on ARM. It is possible to explicitly enable CONFIG_EVENTFD in expert settings, while MMIO binding support in KVM will still be missing. Signed-off-by: Stefan Hajnoczi Signed-off-by: Pavel Fedin Message-Id: <006e01d12377$0b9c2d40$22d487c0$@samsung.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Paolo Bonzini --- kvm-all.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'kvm-all.c') diff --git a/kvm-all.c b/kvm-all.c index a45c92bd1c..ed707fe580 100644 --- a/kvm-all.c +++ b/kvm-all.c @@ -1628,8 +1628,10 @@ static int kvm_init(MachineState *ms) kvm_state = s; - s->memory_listener.listener.eventfd_add = kvm_mem_ioeventfd_add; - s->memory_listener.listener.eventfd_del = kvm_mem_ioeventfd_del; + if (kvm_eventfds_allowed) { + s->memory_listener.listener.eventfd_add = kvm_mem_ioeventfd_add; + s->memory_listener.listener.eventfd_del = kvm_mem_ioeventfd_del; + } s->memory_listener.listener.coalesced_mmio_add = kvm_coalesce_mmio_region; s->memory_listener.listener.coalesced_mmio_del = kvm_uncoalesce_mmio_region; -- cgit v1.2.3