xen/sysctl: wrap around XEN_SYSCTL_readconsole

The following functions is to deal with XEN_SYSCTL_readconsole sub-op, and
shall be wrapped:
- xsm_readconsole()
- read_console_ring()

Signed-off-by: Penny Zheng <Penny.Zheng@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Daniel P. Smith <dpsmith@apertussolutions.com>

xen/drivers/char/console.c

@@ -368,6 +368,7 @@ static void conring_puts(const char *str, size_t len)
         conringc = conringp - conring_size;
 }
 
+#ifdef CONFIG_SYSCTL
 long read_console_ring(struct xen_sysctl_readconsole *op)
 {
     XEN_GUEST_HANDLE_PARAM(char) str;
@@ -410,6 +411,7 @@ long read_console_ring(struct xen_sysctl_readconsole *op)
 
     return 0;
 }
+#endif /* CONFIG_SYSCTL */
 
 
 /*

xen/include/xsm/xsm.h

@@ -270,7 +270,11 @@ static inline int xsm_sysctl(xsm_default_t def, int cmd)
 
 static inline int xsm_readconsole(xsm_default_t def, uint32_t clear)
 {
+#ifdef CONFIG_SYSCTL
     return alternative_call(xsm_ops.readconsole, clear);
+#else
+    return -EOPNOTSUPP;
+#endif
 }
 
 static inline int xsm_evtchn_unbound(

xen/xsm/dummy.c

@@ -24,8 +24,8 @@ static const struct xsm_ops __initconst_cf_clobber dummy_ops = {
     .domctl                        = xsm_domctl,
 #ifdef CONFIG_SYSCTL
     .sysctl                        = xsm_sysctl,
-#endif
     .readconsole                   = xsm_readconsole,
+#endif
 
     .evtchn_unbound                = xsm_evtchn_unbound,
     .evtchn_interdomain            = xsm_evtchn_interdomain,

xen/xsm/flask/hooks.c

@@ -934,7 +934,6 @@ static int cf_check flask_sysctl(int cmd)
         return avc_unknown_permission("sysctl", cmd);
     }
 }
-#endif /* CONFIG_SYSCTL */
 
 static int cf_check flask_readconsole(uint32_t clear)
 {
@@ -945,6 +944,7 @@ static int cf_check flask_readconsole(uint32_t clear)
 
     return domain_has_xen(current->domain, perms);
 }
+#endif /* CONFIG_SYSCTL */
 
 static inline uint32_t resource_to_perm(uint8_t access)
 {
@@ -1888,8 +1888,8 @@ static const struct xsm_ops __initconst_cf_clobber flask_ops = {
     .domctl = flask_domctl,
 #ifdef CONFIG_SYSCTL
     .sysctl = flask_sysctl,
-#endif
     .readconsole = flask_readconsole,
+#endif
 
     .evtchn_unbound = flask_evtchn_unbound,
     .evtchn_interdomain = flask_evtchn_interdomain,