domctl: add force flag to xen_domctl_vcpuaffinity for undoing pin override

Add a XEN_VCPUAFFINITY_FORCE flag to xen_domctl_vcpuaffinity structure
which will allow to undo a SCHEDOP_pin_override in case of a driver
error of the hardware domain which didn't do the expected
SCHEDOP_pin_override with cpu < 0 which would have done the undo
operation.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/common/domctl.c

@@ -782,6 +782,12 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
                 break;
             }
 
+            /* Undo a stuck SCHED_pin_override? */
+            if ( vcpuaff->flags & XEN_VCPUAFFINITY_FORCE )
+                vcpu_pin_override(v, -1);
+
+            ret = 0;
+
             /*
              * We both set a new affinity and report back to the caller what
              * the scheduler will be effectively using.

xen/include/public/domctl.h

@@ -307,6 +307,9 @@ struct xen_domctl_vcpuaffinity {
  /* Set/get the soft affinity for vcpu */
 #define _XEN_VCPUAFFINITY_SOFT  1
 #define XEN_VCPUAFFINITY_SOFT   (1U<<_XEN_VCPUAFFINITY_SOFT)
+ /* Undo SCHEDOP_pin_override */
+#define _XEN_VCPUAFFINITY_FORCE 2
+#define XEN_VCPUAFFINITY_FORCE  (1U<<_XEN_VCPUAFFINITY_FORCE)
     uint32_t flags;
     /*
      * IN/OUT variables.