hw/xen: Implement EVTCHNOP_status

This adds the basic structure for maintaining the port table and reporting
the status of ports therein.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>

hw/i386/kvm/xen_evtchn.c

@@ -22,6 +22,7 @@
 #include "hw/sysbus.h"
 #include "hw/xen/xen.h"
 #include "xen_evtchn.h"
+#include "xen_overlay.h"
 
 #include "sysemu/kvm.h"
 #include "sysemu/kvm_xen.h"
@@ -33,6 +34,22 @@
 #define TYPE_XEN_EVTCHN "xen-evtchn"
 OBJECT_DECLARE_SIMPLE_TYPE(XenEvtchnState, XEN_EVTCHN)
 
+typedef struct XenEvtchnPort {
+    uint32_t vcpu;      /* Xen/ACPI vcpu_id */
+    uint16_t type;      /* EVTCHNSTAT_xxxx */
+    uint16_t type_val;  /* pirq# / virq# / remote port according to type */
+} XenEvtchnPort;
+
+#define COMPAT_EVTCHN_2L_NR_CHANNELS            1024
+
+/*
+ * For unbound/interdomain ports there are only two possible remote
+ * domains; self and QEMU. Use a single high bit in type_val for that,
+ * and the low bits for the remote port number (or 0 for unbound).
+ */
+#define PORT_INFO_TYPEVAL_REMOTE_QEMU           0x8000
+#define PORT_INFO_TYPEVAL_REMOTE_PORT_MASK      0x7FFF
+
 struct XenEvtchnState {
     /*< private >*/
     SysBusDevice busdev;
@@ -42,6 +59,8 @@ struct XenEvtchnState {
     bool evtchn_in_kernel;
 
     QemuMutex port_lock;
+    uint32_t nr_ports;
+    XenEvtchnPort port_table[EVTCHN_2L_NR_CHANNELS];
 };
 
 struct XenEvtchnState *xen_evtchn_singleton;
@@ -65,6 +84,18 @@ static bool xen_evtchn_is_needed(void *opaque)
     return xen_mode == XEN_EMULATE;
 }
 
+static const VMStateDescription xen_evtchn_port_vmstate = {
+    .name = "xen_evtchn_port",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(vcpu, XenEvtchnPort),
+        VMSTATE_UINT16(type, XenEvtchnPort),
+        VMSTATE_UINT16(type_val, XenEvtchnPort),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const VMStateDescription xen_evtchn_vmstate = {
     .name = "xen_evtchn",
     .version_id = 1,
@@ -73,6 +104,9 @@ static const VMStateDescription xen_evtchn_vmstate = {
     .post_load = xen_evtchn_post_load,
     .fields = (VMStateField[]) {
         VMSTATE_UINT64(callback_param, XenEvtchnState),
+        VMSTATE_UINT32(nr_ports, XenEvtchnState),
+        VMSTATE_STRUCT_VARRAY_UINT32(port_table, XenEvtchnState, nr_ports, 1,
+                                     xen_evtchn_port_vmstate, XenEvtchnPort),
         VMSTATE_END_OF_LIST()
     }
 };
@@ -153,3 +187,73 @@ int xen_evtchn_set_callback_param(uint64_t param)
 
     return ret;
 }
+
+static bool valid_port(evtchn_port_t port)
+{
+    if (!port) {
+        return false;
+    }
+
+    if (xen_is_long_mode()) {
+        return port < EVTCHN_2L_NR_CHANNELS;
+    } else {
+        return port < COMPAT_EVTCHN_2L_NR_CHANNELS;
+    }
+}
+
+int xen_evtchn_status_op(struct evtchn_status *status)
+{
+    XenEvtchnState *s = xen_evtchn_singleton;
+    XenEvtchnPort *p;
+
+    if (!s) {
+        return -ENOTSUP;
+    }
+
+    if (status->dom != DOMID_SELF && status->dom != xen_domid) {
+        return -ESRCH;
+    }
+
+    if (!valid_port(status->port)) {
+        return -EINVAL;
+    }
+
+    qemu_mutex_lock(&s->port_lock);
+
+    p = &s->port_table[status->port];
+
+    status->status = p->type;
+    status->vcpu = p->vcpu;
+
+    switch (p->type) {
+    case EVTCHNSTAT_unbound:
+        if (p->type_val & PORT_INFO_TYPEVAL_REMOTE_QEMU) {
+            status->u.unbound.dom = DOMID_QEMU;
+        } else {
+            status->u.unbound.dom = xen_domid;
+        }
+        break;
+
+    case EVTCHNSTAT_interdomain:
+        if (p->type_val & PORT_INFO_TYPEVAL_REMOTE_QEMU) {
+            status->u.interdomain.dom = DOMID_QEMU;
+        } else {
+            status->u.interdomain.dom = xen_domid;
+        }
+
+        status->u.interdomain.port = p->type_val &
+            PORT_INFO_TYPEVAL_REMOTE_PORT_MASK;
+        break;
+
+    case EVTCHNSTAT_pirq:
+        status->u.pirq = p->type_val;
+        break;
+
+    case EVTCHNSTAT_virq:
+        status->u.virq = p->type_val;
+        break;
+    }
+
+    qemu_mutex_unlock(&s->port_lock);
+    return 0;
+}

hw/i386/kvm/xen_evtchn.h

@@ -15,4 +15,7 @@
 void xen_evtchn_create(void);
 int xen_evtchn_set_callback_param(uint64_t param);
 
+struct evtchn_status;
+int xen_evtchn_status_op(struct evtchn_status *status);
+
 #endif /* QEMU_XEN_EVTCHN_H */

target/i386/kvm/xen-emu.c

@@ -776,9 +776,10 @@ static bool kvm_xen_hcall_vcpu_op(struct kvm_xen_exit *exit, X86CPU *cpu,
     return true;
 }
 
-static bool kvm_xen_hcall_evtchn_op(struct kvm_xen_exit *exit,
+static bool kvm_xen_hcall_evtchn_op(struct kvm_xen_exit *exit, X86CPU *cpu,
                                     int cmd, uint64_t arg)
 {
+    CPUState *cs = CPU(cpu);
     int err = -ENOSYS;
 
     switch (cmd) {
@@ -789,6 +790,21 @@ static bool kvm_xen_hcall_evtchn_op(struct kvm_xen_exit *exit,
         err = -ENOSYS;
         break;
 
+    case EVTCHNOP_status: {
+        struct evtchn_status status;
+
+        qemu_build_assert(sizeof(status) == 24);
+        if (kvm_copy_from_gva(cs, arg, &status, sizeof(status))) {
+            err = -EFAULT;
+            break;
+        }
+
+        err = xen_evtchn_status_op(&status);
+        if (!err && kvm_copy_to_gva(cs, arg, &status, sizeof(status))) {
+            err = -EFAULT;
+        }
+        break;
+    }
     default:
         return false;
     }
@@ -914,7 +930,7 @@ static bool do_kvm_xen_handle_exit(X86CPU *cpu, struct kvm_xen_exit *exit)
         return kvm_xen_hcall_sched_op(exit, cpu, exit->u.hcall.params[0],
                                       exit->u.hcall.params[1]);
     case __HYPERVISOR_event_channel_op:
-        return kvm_xen_hcall_evtchn_op(exit, exit->u.hcall.params[0],
+        return kvm_xen_hcall_evtchn_op(exit, cpu, exit->u.hcall.params[0],
                                        exit->u.hcall.params[1]);
     case __HYPERVISOR_vcpu_op:
         return kvm_xen_hcall_vcpu_op(exit, cpu,