[PATCHv1 1/5] domctl: Add op to get/set generic numeric parameters

[David Vrabel <david.vrabel@citrix.com>]

Add XEN_DOMCTL_param to get/set generic numeric parameters for a domain.
This should reduce the number of specialized domctls that need to be
added.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 xen/arch/x86/domctl.c       | 14 ++++++++++++++
 xen/common/domctl.c         | 11 +++++++++++
 xen/include/public/domctl.h | 21 +++++++++++++++++++++
 xen/include/xen/domain.h    |  3 +++
 4 files changed, 49 insertions(+)

diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index 55aecdc..3a3ebbf 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1408,6 +1408,20 @@ void arch_get_info_guest(struct vcpu *v, vcpu_guest_context_u c)
 #undef c
 }
 
+int arch_domctl_param(struct domain *d, uint32_t param, bool_t set,
+                      uint64_t *value)
+{
+    uint64_t new_value = *value;
+
+    switch ( param )
+    {
+    default:
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index 22fa5d5..54c51ba 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -1186,6 +1186,17 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
             copyback = 1;
         break;
 
+    case XEN_DOMCTL_param:
+    {
+        uint32_t param = op->u.param.param & ~XEN_DOMCTL_PARAM_SET;
+        bool_t set = !!(op->u.param.param & XEN_DOMCTL_PARAM_SET);
+
+        ret = arch_domctl_param(d, param, set, &op->u.param.value);
+        if ( ret == 0 )
+            copyback = 1;
+        break;
+    }
+
     default:
         ret = arch_do_domctl(op, d, u_domctl);
         break;
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index a934318..330b3e7 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -1092,6 +1092,25 @@ struct xen_domctl_psr_cat_op {
 typedef struct xen_domctl_psr_cat_op xen_domctl_psr_cat_op_t;
 DEFINE_XEN_GUEST_HANDLE(xen_domctl_psr_cat_op_t);
 
+/*
+ * Get/set a per-domain numeric parameter.
+ *
+ * If bit 31 of @param is set, the original value is returned and the
+ * new value is written.  If bit 31 is clear, the value is returned.
+ *
+ * Not all parameters are valid for all architectures or domain types.
+ */
+#define XEN_DOMCTL_PARAM_SET (1u << 31)
+
+struct xen_domctl_param {
+    /* IN */
+    uint32_t param;
+    /* IN/OUT */
+    uint64_t value;
+};
+typedef struct xen_domctl_param xen_domctl_param;
+DEFINE_XEN_GUEST_HANDLE(xen_domctl_param);
+
 struct xen_domctl {
     uint32_t cmd;
 #define XEN_DOMCTL_createdomain                   1
@@ -1169,6 +1188,7 @@ struct xen_domctl {
 #define XEN_DOMCTL_monitor_op                    77
 #define XEN_DOMCTL_psr_cat_op                    78
 #define XEN_DOMCTL_soft_reset                    79
+#define XEN_DOMCTL_param                         80
 #define XEN_DOMCTL_gdbsx_guestmemio            1000
 #define XEN_DOMCTL_gdbsx_pausevcpu             1001
 #define XEN_DOMCTL_gdbsx_unpausevcpu           1002
@@ -1231,6 +1251,7 @@ struct xen_domctl {
         struct xen_domctl_psr_cmt_op        psr_cmt_op;
         struct xen_domctl_monitor_op        monitor_op;
         struct xen_domctl_psr_cat_op        psr_cat_op;
+        struct xen_domctl_param             param;
         uint8_t                             pad[128];
     } u;
 };
diff --git a/xen/include/xen/domain.h b/xen/include/xen/domain.h
index a1a6f25..a8a6d7d 100644
--- a/xen/include/xen/domain.h
+++ b/xen/include/xen/domain.h
@@ -77,6 +77,9 @@ void arch_dump_domain_info(struct domain *d);
 
 int arch_vcpu_reset(struct vcpu *);
 
+int arch_domctl_param(struct domain *d, uint32_t param, bool_t set,
+                      uint64_t *value);
+
 extern spinlock_t vcpu_alloc_lock;
 bool_t domctl_lock_acquire(void);
 void domctl_lock_release(void);
-- 
2.1.4