KVM: x86/xen: evtchn unmask support

Handle hypercall to unmasks event channel ports.

A subtlety here is that we deliver an upcall if an actual unmask
happened and the event channel was pending (and if the vcpu-wide
evtchn_pending_sel was not already marked pending.)

Co-developed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 420e3ebb66bcd6b245f59c874dffd0ade95d511b..1988ed3866bfe7e3e547a4715facbc0ba17c912b 100644 (file)
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -2102,6 +2102,29 @@ static int shim_hcall_evtchn_send(struct kvm_xen *dom0, struct evtchn_send *snd)
        return 0;
 }
 
+static int shim_hcall_evtchn_unmask(struct kvm_xen *dom0, int port)
+{
+       struct shared_info *s = HYPERVISOR_shared_info;
+       struct evtchnfd *evtchnfd;
+       struct vcpu_info *v;
+
+       evtchnfd = idr_find(&dom0->port_to_evt, port);
+       if (!evtchnfd)
+               return -ENOENT;
+
+       v = per_cpu(xen_vcpu, evtchnfd->vcpu);
+
+       if (test_and_clear_bit(port, (unsigned long *) s->evtchn_mask) &&
+           test_bit(port, (unsigned long *) s->evtchn_pending) &&
+           !test_and_set_bit(port / BITS_PER_EVTCHN_WORD,
+                             (unsigned long *) &v->evtchn_pending_sel)) {
+               kvm_xen_evtchn_2l_vcpu_set_pending(v);
+               return kvm_xen_evtchn_call_function(evtchnfd);
+       }
+
+       return 0;
+}
+
 static int shim_hcall_evtchn(int op, void *p)
 {
        int ret;
@@ -2151,6 +2174,13 @@ static int shim_hcall_evtchn(int op, void *p)
                un->port = evt.port;
                break;
        }
+       case EVTCHNOP_unmask: {
+               struct evtchn_unmask *unmask;
+
+               unmask = (struct evtchn_unmask *) p;
+               ret = shim_hcall_evtchn_unmask(xen_shim, unmask->port);
+               break;
+       }
        case EVTCHNOP_send: {
                struct evtchn_send *send;