[Xen-devel] [PATCH] vm_event: Add a new opcode to get VM_EVENT_INTERFACE_VERSION

[Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>]

Currently, the VM_EVENT_INTERFACE_VERSION is determined at runtime, by
inspecting the corresponding field in a vm_event_request. This helper
opcode will query the hypervisor supported version before the vm_event
related structures and layout are set-up.

Signed-off-by: Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>
---
 tools/libxc/include/xenctrl.h |  5 +++++
 tools/libxc/xc_vm_event.c     | 18 +++++++++++++++++-
 xen/common/domctl.c           |  1 +
 xen/common/vm_event.c         | 15 ++++++++++++++-
 xen/include/public/domctl.h   | 17 +++++++++++++----
 5 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 31cdda7..b801b85 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2003,6 +2003,11 @@ int xc_set_mem_access_multi(xc_interface *xch, uint32_t 
domain_id,
 int xc_get_mem_access(xc_interface *xch, uint32_t domain_id,
                       uint64_t pfn, xenmem_access_t *access);
 
+/*
+ * Returns the VM_EVENT_INTERFACE version.
+ */
+int xc_vm_event_get_interface_version(xc_interface *xch);
+
 /***
  * Monitor control operations.
  *
diff --git a/tools/libxc/xc_vm_event.c b/tools/libxc/xc_vm_event.c
index 8674607..10ebc3c 100644
--- a/tools/libxc/xc_vm_event.c
+++ b/tools/libxc/xc_vm_event.c
@@ -35,7 +35,7 @@ int xc_vm_event_control(xc_interface *xch, uint32_t 
domain_id, unsigned int op,
 
     rc = do_domctl(xch, &domctl);
     if ( !rc && port )
-        *port = domctl.u.vm_event_op.port;
+        *port = domctl.u.vm_event_op.u.enable.port;
     return rc;
 }
 
@@ -156,6 +156,22 @@ void *xc_vm_event_enable(xc_interface *xch, uint32_t 
domain_id, int param,
     return ring_page;
 }
 
+int xc_vm_event_get_interface_version(xc_interface *xch)
+{
+    DECLARE_DOMCTL;
+    int rc;
+
+    domctl.cmd = XEN_DOMCTL_vm_event_op;
+    domctl.domain = DOMID_INVALID;
+    domctl.u.vm_event_op.op = XEN_VM_EVENT_GET_INTERFACE_VERSION;
+    domctl.u.vm_event_op.mode = XEN_DOMCTL_VM_EVENT_OP_MONITOR;
+
+    rc = do_domctl(xch, &domctl);
+    if ( !rc )
+        rc = domctl.u.vm_event_op.u.get_interface_version.value;
+    return rc;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index d08b627..bade9a6 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -392,6 +392,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) 
u_domctl)
     switch ( op->cmd )
     {
     case XEN_DOMCTL_test_assign_device:
+    case XEN_DOMCTL_vm_event_op:
         if ( op->domain == DOMID_INVALID )
         {
     case XEN_DOMCTL_createdomain:
diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
index 26cfa2c..cbdade3 100644
--- a/xen/common/vm_event.c
+++ b/xen/common/vm_event.c
@@ -88,7 +88,7 @@ static int vm_event_enable(
     if ( rc < 0 )
         goto err;
 
-    (*ved)->xen_port = vec->port = rc;
+    (*ved)->xen_port = vec->u.enable.port = rc;
 
     /* Prepare ring buffer */
     FRONT_RING_INIT(&(*ved)->front_ring,
@@ -592,6 +592,19 @@ int vm_event_domctl(struct domain *d, struct 
xen_domctl_vm_event_op *vec,
 {
     int rc;
 
+    if ( vec->op == XEN_VM_EVENT_GET_INTERFACE_VERSION )
+    {
+        vec->u.get_interface_version.value = VM_EVENT_INTERFACE_VERSION;
+        return 0;
+    }
+
+    if ( unlikely(d == NULL) )
+    {
+        gdprintk(XENLOG_INFO,
+                 "Tried to do a memory event op on an invalid domain.\n");
+        return -EINVAL;
+    }
+
     rc = xsm_vm_event_control(XSM_PRIV, d, vec->mode, vec->op);
     if ( rc )
         return rc;
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 7e1cf21..f222d1e 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -778,9 +778,10 @@ struct xen_domctl_gdbsx_domstatus {
  * to the hypervisor to pull responses (resume) from the given
  * ring.
  */
-#define XEN_VM_EVENT_ENABLE               0
-#define XEN_VM_EVENT_DISABLE              1
-#define XEN_VM_EVENT_RESUME               2
+#define XEN_VM_EVENT_ENABLE                 0
+#define XEN_VM_EVENT_DISABLE                1
+#define XEN_VM_EVENT_RESUME                 2
+#define XEN_VM_EVENT_GET_INTERFACE_VERSION  3
 
 /*
  * Domain memory paging
@@ -843,7 +844,15 @@ struct xen_domctl_vm_event_op {
     uint32_t       op;           /* XEN_VM_EVENT_* */
     uint32_t       mode;         /* XEN_DOMCTL_VM_EVENT_OP_* */
 
-    uint32_t port;              /* OUT: event channel for ring */
+    union {
+        struct {
+            uint32_t port;       /* OUT: event channel for ring */
+        } enable;
+
+        struct {
+            uint32_t value;
+        } get_interface_version;
+    } u;
 };
 
 /*
-- 
2.7.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel