[20/23] hyperv: process POST_MESSAGE hypercall

Commit Message

Roman Kagan June 6, 2017, 6:19 p.m. UTC

Add handling of POST_MESSAGE hypercall.  For that, add an interface to
regsiter a handler for the messages arrived from the guest on a
particular connection id (IOW set up a message connection in Hyper-V
speak).

Signed-off-by: Roman Kagan <[e-mail]>
---
 target/i386/hyperv.h |  5 +++
 target/i386/hyperv.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+)

Comments

Paolo Bonzini June 14, 2017, 11:19 a.m. UTC | #1

On 06/06/2017 20:19, Roman Kagan wrote:
> +typedef struct MsgHandler {
> +    struct rcu_head rcu;
> +    QLIST_ENTRY(MsgHandler) le;
> +    uint32_t conn_id;
> +    HvMsgHandler handler;
> +    void *data;
> +} MsgHandler;
> +
> +static QLIST_HEAD(, MsgHandler) msg_handlers;
> +static QemuMutex msg_handlers_mutex;

Maybe use the same mutex for event and message handlers?

Paolo

Roman Kagan June 14, 2017, 2:20 p.m. UTC | #2

On Wed, Jun 14, 2017 at 01:19:21PM +0200, Paolo Bonzini wrote:
> On 06/06/2017 20:19, Roman Kagan wrote:
> > +typedef struct MsgHandler {
> > +    struct rcu_head rcu;
> > +    QLIST_ENTRY(MsgHandler) le;
> > +    uint32_t conn_id;
> > +    HvMsgHandler handler;
> > +    void *data;
> > +} MsgHandler;
> > +
> > +static QLIST_HEAD(, MsgHandler) msg_handlers;
> > +static QemuMutex msg_handlers_mutex;
> 
> Maybe use the same mutex for event and message handlers?

Are there other benefits in it beside saving 40 bytes?

Roman.

Paolo Bonzini June 14, 2017, 2:30 p.m. UTC | #3

On 14/06/2017 16:20, Roman Kagan wrote:
> On Wed, Jun 14, 2017 at 01:19:21PM +0200, Paolo Bonzini wrote:
>> On 06/06/2017 20:19, Roman Kagan wrote:
>>> +typedef struct MsgHandler {
>>> +    struct rcu_head rcu;
>>> +    QLIST_ENTRY(MsgHandler) le;
>>> +    uint32_t conn_id;
>>> +    HvMsgHandler handler;
>>> +    void *data;
>>> +} MsgHandler;
>>> +
>>> +static QLIST_HEAD(, MsgHandler) msg_handlers;
>>> +static QemuMutex msg_handlers_mutex;
>>
>> Maybe use the same mutex for event and message handlers?
> 
> Are there other benefits in it beside saving 40 bytes?

It's generally simpler if one module only uses one mutex, you don't have
to think of the interactions.  Since everything is RCU-protected on the
read-side, it should not matter for performance.

Paolo

Patch

diff --git a/target/i386/hyperv.h b/target/i386/hyperv.h
index d2630ac..f82c770 100644
--- a/target/i386/hyperv.h
+++ b/target/i386/hyperv.h
@@ -41,6 +41,11 @@  int hyperv_post_msg(HvSintRoute *sint_route, struct hyperv_message *msg);
 
 int hyperv_set_evt_flag(HvSintRoute *sint_route, unsigned evtno);
 
+struct hyperv_post_message_input;
+typedef uint64_t (*HvMsgHandler)(const struct hyperv_post_message_input *msg,
+                                 void *data);
+int hyperv_set_msg_handler(uint32_t conn_id, HvMsgHandler handler, void *data);
+
 int hyperv_set_evt_notifier(uint32_t conn_id, EventNotifier *notifier);
 
 #endif
diff --git a/target/i386/hyperv.c b/target/i386/hyperv.c
index 030184e..50386a2 100644
--- a/target/i386/hyperv.c
+++ b/target/i386/hyperv.c
@@ -232,6 +232,17 @@  static void async_synic_update(CPUState *cs, run_on_cpu_data data)
     qemu_mutex_unlock_iothread();
 }
 
+typedef struct MsgHandler {
+    struct rcu_head rcu;
+    QLIST_ENTRY(MsgHandler) le;
+    uint32_t conn_id;
+    HvMsgHandler handler;
+    void *data;
+} MsgHandler;
+
+static QLIST_HEAD(, MsgHandler) msg_handlers;
+static QemuMutex msg_handlers_mutex;
+
 typedef struct EvtHandler {
     struct rcu_head rcu;
     QLIST_ENTRY(EvtHandler) le;
@@ -244,10 +255,46 @@  static QemuMutex evt_handlers_mutex;
 
 static void __attribute__((constructor)) hv_init(void)
 {
+    QLIST_INIT(&msg_handlers);
+    qemu_mutex_init(&msg_handlers_mutex);
     QLIST_INIT(&evt_handlers);
     qemu_mutex_init(&evt_handlers_mutex);
 }
 
+int hyperv_set_msg_handler(uint32_t conn_id, HvMsgHandler handler, void *data)
+{
+    int ret;
+    MsgHandler *mh;
+
+    qemu_mutex_lock(&msg_handlers_mutex);
+    QLIST_FOREACH(mh, &msg_handlers, le) {
+        if (mh->conn_id == conn_id) {
+            if (handler) {
+                ret = -EEXIST;
+            } else {
+                QLIST_REMOVE_RCU(mh, le);
+                g_free_rcu(mh, rcu);
+                ret = 0;
+            }
+            goto unlock;
+        }
+    }
+
+    if (handler) {
+        mh = g_new(MsgHandler, 1);
+        mh->conn_id = conn_id;
+        mh->handler = handler;
+        mh->data = data;
+        QLIST_INSERT_HEAD_RCU(&msg_handlers, mh, le);
+        ret = 0;
+    } else {
+        ret = -ENOENT;
+    }
+unlock:
+    qemu_mutex_unlock(&msg_handlers_mutex);
+    return ret;
+}
+
 int hyperv_set_evt_notifier(uint32_t conn_id, EventNotifier *notifier)
 {
     int ret;
@@ -281,6 +328,46 @@  unlock:
     return ret;
 }
 
+static uint64_t hvcall_post_message(uint64_t param, bool fast)
+{
+    uint64_t ret;
+    hwaddr len;
+    struct hyperv_post_message_input *msg;
+    MsgHandler *mh;
+
+    if (fast) {
+        return HV_STATUS_INVALID_HYPERCALL_CODE;
+    }
+    if (param & (__alignof__(*msg) - 1)) {
+        return HV_STATUS_INVALID_ALIGNMENT;
+    }
+
+    len = sizeof(*msg);
+    msg = cpu_physical_memory_map(param, &len, 0);
+    if (len < sizeof(*msg)) {
+        ret = HV_STATUS_INSUFFICIENT_MEMORY;
+        goto unmap;
+    }
+    if (msg->payload_size > sizeof(msg->payload)) {
+        ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+        goto unmap;
+    }
+
+    ret = HV_STATUS_INVALID_CONNECTION_ID;
+    rcu_read_lock();
+    QLIST_FOREACH_RCU(mh, &msg_handlers, le) {
+        if (mh->conn_id == (msg->connection_id & HV_CONNECTION_ID_MASK)) {
+            ret = mh->handler(msg, mh->data);
+            break;
+        }
+    }
+    rcu_read_unlock();
+
+unmap:
+    cpu_physical_memory_unmap(msg, len, 0, 0);
+    return ret;
+}
+
 static uint64_t sigevent_params(hwaddr addr, uint32_t *conn_id)
 {
     uint64_t ret;
@@ -364,6 +451,9 @@  int kvm_hv_handle_exit(X86CPU *cpu, struct kvm_hyperv_exit *exit)
         uint64_t param = exit->u.hcall.params[0];
 
         switch (code) {
+        case HV_POST_MESSAGE:
+            exit->u.hcall.result = hvcall_post_message(param, fast);
+            break;
         case HV_SIGNAL_EVENT:
             exit->u.hcall.result = hvcall_signal_event(param, fast);
             break;