[PATCH v2] x86/domctl: Conditionalise x86 domctl using DCE rather than ifdef

[Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx>]

Make them uniformly return EOPNOTSUPP when their dependent features
are absent. Otherwise the compiler loses context and they might return
ENOSYS instead.

debug_op, mem_sharing_op, p2m_audit and psr_alloc change behaviour and
return EOPNOTSUPP when compiled out, rather than ENOSYS.

While at it, remove the public headers from mem_sharing.h (forward
declarations are fine) and add a missing xen/sched.h include (for
complete struct domain definition).

Signed-off-by: Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx>
---
v2:
  * Also cover p2m_audit
  * in mem_sharing.h, restrict the xen/sched.h inclusion to the ifdef.
  * bugfix: make psr handler correctly exit early when !IS_ENABLED(...PSR)
---
 xen/arch/x86/domctl.c                  | 33 +++++++++++++++-----------
 xen/arch/x86/include/asm/mem_sharing.h | 12 ++++++----
 xen/arch/x86/include/asm/p2m.h         | 10 ++++----
 3 files changed, 31 insertions(+), 24 deletions(-)

diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index d9521808dc..942f41c584 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -220,15 +220,15 @@ long arch_do_domctl(
     {
 
     case XEN_DOMCTL_shadow_op:
-#ifdef CONFIG_PAGING
+        ret = -EOPNOTSUPP;
+        if ( !IS_ENABLED(CONFIG_PAGING) )
+            break;
+
         ret = paging_domctl(d, &domctl->u.shadow_op, u_domctl, 0);
         if ( ret == -ERESTART )
             return hypercall_create_continuation(
                        __HYPERVISOR_paging_domctl_cont, "h", u_domctl);
         copyback = true;
-#else
-        ret = -EOPNOTSUPP;
-#endif
         break;
 
     case XEN_DOMCTL_ioport_permission:
@@ -842,11 +842,14 @@ long arch_do_domctl(
         }
         break;
 
-#ifdef CONFIG_HVM
     case XEN_DOMCTL_debug_op:
     {
         struct vcpu *v;
 
+        ret = -EOPNOTSUPP;
+        if ( !IS_ENABLED(CONFIG_HVM) )
+            break;
+
         ret = -EINVAL;
         if ( (domctl->u.debug_op.vcpu >= d->max_vcpus) ||
              ((v = d->vcpu[domctl->u.debug_op.vcpu]) == NULL) )
@@ -860,7 +863,6 @@ long arch_do_domctl(
         ret = hvm_debug_op(v, domctl->u.debug_op.op);
         break;
     }
-#endif
 
     case XEN_DOMCTL_gdbsx_guestmemio:
     case XEN_DOMCTL_gdbsx_pausevcpu:
@@ -1033,15 +1035,18 @@ long arch_do_domctl(
         break;
     }
 
-#ifdef CONFIG_MEM_SHARING
     case XEN_DOMCTL_mem_sharing_op:
+        ret = -EOPNOTSUPP;
+        if ( !IS_ENABLED(CONFIG_MEM_SHARING) )
+            break;
+
         ret = mem_sharing_domctl(d, &domctl->u.mem_sharing_op);
         break;
-#endif
 
-#if P2M_AUDIT
     case XEN_DOMCTL_audit_p2m:
-        if ( d == currd )
+        if ( !P2M_AUDIT )
+            ret = -EOPNOTSUPP;
+        else if ( d == currd )
             ret = -EPERM;
         else
         {
@@ -1052,7 +1057,6 @@ long arch_do_domctl(
             copyback = true;
         }
         break;
-#endif /* P2M_AUDIT */
 
     case XEN_DOMCTL_set_broken_page_p2m:
     {
@@ -1240,9 +1244,12 @@ long arch_do_domctl(
         break;
 
     case XEN_DOMCTL_psr_alloc:
+        ret = -EOPNOTSUPP;
+        if ( !IS_ENABLED(CONFIG_X86_PSR) )
+            break;
+
         switch ( domctl->u.psr_alloc.cmd )
         {
-#ifdef CONFIG_X86_PSR
         case XEN_DOMCTL_PSR_SET_L3_CBM:
             ret = psr_set_val(d, domctl->u.psr_alloc.target,
                               domctl->u.psr_alloc.data,
@@ -1305,8 +1312,6 @@ long arch_do_domctl(
 
 #undef domctl_psr_get_val
 
-#endif /* CONFIG_X86_PSR */
-
         default:
             ret = -EOPNOTSUPP;
             break;
diff --git a/xen/arch/x86/include/asm/mem_sharing.h 
b/xen/arch/x86/include/asm/mem_sharing.h
index 040962f690..c66cc912db 100644
--- a/xen/arch/x86/include/asm/mem_sharing.h
+++ b/xen/arch/x86/include/asm/mem_sharing.h
@@ -9,10 +9,12 @@
 #ifndef __MEM_SHARING_H__
 #define __MEM_SHARING_H__
 
-#include <public/domctl.h>
-#include <public/memory.h>
+struct xen_domctl_mem_sharing_op;
 
 #ifdef CONFIG_MEM_SHARING
+#include <xen/sched.h>
+
+struct xen_mem_sharing_op;
 
 #define mem_sharing_enabled(d) ((d)->arch.hvm.mem_sharing.enabled)
 
@@ -92,8 +94,6 @@ int mem_sharing_fork_reset(struct domain *d, bool reset_state,
 int mem_sharing_notify_enomem(struct domain *d, unsigned long gfn,
                               bool allow_sleep);
 int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg);
-int mem_sharing_domctl(struct domain *d,
-                       struct xen_domctl_mem_sharing_op *mec);
 
 /*
  * Scans the p2m and relinquishes any shared pages, destroying
@@ -103,6 +103,7 @@ int mem_sharing_domctl(struct domain *d,
 int relinquish_shared_pages(struct domain *d);
 
 #else
+struct domctl;
 
 #define mem_sharing_enabled(d) false
 
@@ -147,4 +148,7 @@ static inline int mem_sharing_fork_reset(struct domain *d, 
bool reset_state,
 
 #endif
 
+int mem_sharing_domctl(struct domain *d,
+                       struct xen_domctl_mem_sharing_op *mec);
+
 #endif /* __MEM_SHARING_H__ */
diff --git a/xen/arch/x86/include/asm/p2m.h b/xen/arch/x86/include/asm/p2m.h
index 9016e88411..b2721f8c11 100644
--- a/xen/arch/x86/include/asm/p2m.h
+++ b/xen/arch/x86/include/asm/p2m.h
@@ -806,12 +806,10 @@ static inline void p2m_pt_init(struct p2m_domain *p2m) {}
 void *map_domain_gfn(struct p2m_domain *p2m, gfn_t gfn, mfn_t *mfn,
                      p2m_query_t q, uint32_t *pfec);
 
-#if P2M_AUDIT
-extern void audit_p2m(struct domain *d,
-                      uint64_t *orphans,
-                      uint64_t *m2p_bad,
-                      uint64_t *p2m_bad);
-#endif /* P2M_AUDIT */
+void audit_p2m(struct domain *d,
+               uint64_t *orphans,
+               uint64_t *m2p_bad,
+               uint64_t *p2m_bad);
 
 /* Printouts */
 #define P2M_PRINTK(f, a...)                                \

base-commit: 2fa468919c39aac189623b6c580ce4ff8592d799
-- 
2.43.0