[Xen-devel] [PATCH 25/25] argo: implement the get_config op to query notification config

[Christopher Clark <christopher.w.clark@xxxxxxxxx>]

Needed by a guest to obtain the evtchn port to use, if notifications are via
event channel, so: this operation will return the current notification method
active for the domain, and method-specific configuration data:

    * event channel: port number
    * VIRQ: virq number

Return structure has reserved space intentionally to for future alternative
notification mechanism to return data about both an IRQ number and bound VCPU.

Signed-off-by: Christopher Clark <christopher.clark6@xxxxxxxxxxxxxx>
---
 xen/common/argo.c         | 57 +++++++++++++++++++++++++++++++++++++++++++++++
 xen/include/public/argo.h | 28 +++++++++++++++++++++++
 2 files changed, 85 insertions(+)

diff --git a/xen/common/argo.c b/xen/common/argo.c
index 98de9a9..f6cc764 100644
--- a/xen/common/argo.c
+++ b/xen/common/argo.c
@@ -1656,6 +1656,46 @@ argo_sendv(struct domain *src_d, const argo_addr_t 
*src_addr,
     return ( ret < 0 ) ? ret : len;
 }
 
+static void
+argo_get_config(struct domain *d, argo_get_config_t *get_config)
+{
+    unsigned int method = argo_signal_method(d);
+
+    get_config->signal_method = method;
+
+    switch ( method )
+    {
+        case ARGO_SIGNAL_METHOD_EVTCHN:
+        {
+            read_lock(&argo_lock);
+            read_lock(&d->argo->lock);
+
+            get_config->signal.evtchn = d->argo->evtchn_port;
+
+            read_unlock(&d->argo->lock);
+            read_unlock(&argo_lock);
+
+            argo_dprintk("signal for dom:%d evtchn %u\n", d->domain_id,
+                         get_config->signal.evtchn);
+
+            break;
+        }
+        case ARGO_SIGNAL_METHOD_VIRQ:
+        {
+            get_config->signal.virq = VIRQ_ARGO;
+
+            argo_dprintk("signal for dom:%d virq %u\n", d->domain_id,
+                         get_config->signal.virq);
+            break;
+        }
+        default:
+        {
+            BUG();
+            break;
+        }
+    }
+}
+
 long
 do_argo_message_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg1,
                    XEN_GUEST_HANDLE_PARAM(void) arg2,
@@ -1746,6 +1786,23 @@ do_argo_message_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) 
arg1,
         rc = argo_notify(d, ring_data_hnd);
         break;
     }
+    case ARGO_MESSAGE_OP_get_config:
+    {
+        XEN_GUEST_HANDLE_PARAM(argo_get_config_t) get_config_hnd =
+                   guest_handle_cast(arg1, argo_get_config_t);
+        argo_get_config_t get_config;
+
+        if ( unlikely(!guest_handle_okay(get_config_hnd, 1)) )
+            break;
+
+        argo_get_config(d, &get_config);
+
+        if ( __copy_to_guest(get_config_hnd, &get_config, 1) )
+            break;
+
+        rc = 0;
+        break;
+    }
     default:
         rc = -ENOSYS;
         break;
diff --git a/xen/include/public/argo.h b/xen/include/public/argo.h
index 710baa6..1e78ea0 100644
--- a/xen/include/public/argo.h
+++ b/xen/include/public/argo.h
@@ -20,6 +20,7 @@
 #define __XEN_PUBLIC_ARGO_H__
 
 #include "xen.h"
+#include "event_channel.h"
 
 #define ARGO_RING_MAGIC      0xbd67e163e7777f2fULL
 #define ARGO_RING_DATA_MAGIC 0xcce4d30fbc82e92aULL
@@ -153,6 +154,18 @@ struct argo_ring_message_header
 #define ARGO_SIGNAL_METHOD_EVTCHN      1
 #define ARGO_SIGNAL_METHOD_VIRQ        2
 
+typedef struct argo_get_config
+{
+    uint32_t signal_method;
+    union
+    {
+        evtchn_port_t evtchn;
+        uint32_t virq;
+    } signal;
+    uint32_t reserved;
+} argo_get_config_t;
+DEFINE_XEN_GUEST_HANDLE(argo_get_config_t);
+
 /*
  * Hypercall operations
  */
@@ -244,6 +257,21 @@ struct argo_ring_message_header
  */
 #define ARGO_MESSAGE_OP_notify              4
 
+/*
+ * ARGO_MESSAGE_OP_get_config
+ *
+ * Queries Xen for argo configuration values.
+ *
+ * Used by a guest to obtain the signal method in use for Argo notifications
+ * and the event channel port or isa irq in use.
+ *
+ * arg1: XEN_GUEST_HANDLE(argo_get_config_t)
+ * arg2: NULL
+ * arg3: 0 (ZERO)
+ * arg4: 0 (ZERO)
+ */
+#define ARGO_MESSAGE_OP_get_config          6
+
 /* The maximum size of a guest message that may be sent on an Argo ring. */
 #define ARGO_MAX_MSG_SIZE ((ARGO_MAX_RING_SIZE) - \
         (sizeof(struct argo_ring_message_header)) - \
-- 
2.1.4


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