x86/mmuext: unify okay/rc error handling in do_mmuext_op()

c/s 506db90 "x86/HVM: merge HVM and PVH hypercall tables" introduced a path
whereby 'okay' was used uninitialised, with broke compilation on CentOS 7.

Splitting the error handling like this is fragile and unnecessary.  Drop the
okay variable entirely and just use rc directly, substituting rc = -EINVAL/0
for okay = 0/1.

In addition, two error messages are updated to print rc, and some stray
whitespace is dropped.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Make setting of rc happen consistently after MEM_LOG(), if that is being
used.

Signed-off-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 717546ac282c6c1cac8af9a07ce1dce5c5e5f7cf..305686910e9643206c7b7955dd3a344244174266 100644 (file)
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -2974,7 +2974,7 @@ long do_mmuext_op(
     struct vcpu *curr = current;
     struct domain *d = curr->domain;
     struct domain *pg_owner;
-    int okay, rc = put_old_guest_table(curr);
+    int rc = put_old_guest_table(curr);
 
     if ( unlikely(rc) )
     {
@@ -3053,7 +3053,7 @@ long do_mmuext_op(
             }
         }
 
-        okay = 1;
+        rc = 0;
 
         switch ( op.cmd )
         {
@@ -3087,33 +3087,32 @@ long do_mmuext_op(
             page = get_page_from_gfn(pg_owner, op.arg1.mfn, NULL, P2M_ALLOC);
             if ( unlikely(!page) )
             {
-                okay = 0;
+                rc = -EINVAL;
                 break;
             }
 
             rc = get_page_type_preemptible(page, type);
-            okay = !rc;
-            if ( unlikely(!okay) )
+            if ( unlikely(rc) )
             {
                 if ( rc == -EINTR )
                     rc = -ERESTART;
                 else if ( rc != -ERESTART )
-                    MEM_LOG("Error while pinning mfn %lx", page_to_mfn(page));
+                    MEM_LOG("Error %d while pinning mfn %lx",
+                            rc, page_to_mfn(page));
                 if ( page != curr->arch.old_guest_table )
                     put_page(page);
                 break;
             }
 
-            if ( (rc = xsm_memory_pin_page(XSM_HOOK, d, pg_owner, page)) != 0 )
-                okay = 0;
-            else if ( unlikely(test_and_set_bit(_PGT_pinned,
-                                                &page->u.inuse.type_info)) )
+            rc = xsm_memory_pin_page(XSM_HOOK, d, pg_owner, page);
+            if ( !rc && unlikely(test_and_set_bit(_PGT_pinned,
+                                                  &page->u.inuse.type_info)) )
             {
                 MEM_LOG("Mfn %lx already pinned", page_to_mfn(page));
-                okay = 0;
+                rc = -EINVAL;
             }
 
-            if ( unlikely(!okay) )
+            if ( unlikely(rc) )
                 goto pin_drop;
 
             /* A page is dirtied when its pin status is set. */
@@ -3150,16 +3149,16 @@ long do_mmuext_op(
             page = get_page_from_gfn(pg_owner, op.arg1.mfn, NULL, P2M_ALLOC);
             if ( unlikely(!page) )
             {
-                okay = 0;
                 MEM_LOG("Mfn %lx bad domain", op.arg1.mfn);
+                rc = -EINVAL;
                 break;
             }
 
             if ( !test_and_clear_bit(_PGT_pinned, &page->u.inuse.type_info) )
             {
-                okay = 0;
                 put_page(page);
                 MEM_LOG("Mfn %lx not pinned", op.arg1.mfn);
+                rc = -EINVAL;
                 break;
             }
 
@@ -3212,20 +3211,18 @@ long do_mmuext_op(
             if ( op.arg1.mfn != 0 )
             {
                 if ( paging_mode_refcounts(d) )
-                    okay = get_page_from_pagenr(op.arg1.mfn, d);
+                    rc = get_page_from_pagenr(op.arg1.mfn, d) ? 0 : -EINVAL;
                 else
-                {
                     rc = get_page_and_type_from_pagenr(
                         op.arg1.mfn, PGT_root_page_table, d, 0, 1);
-                    okay = !rc;
-                }
-                if ( unlikely(!okay) )
+
+                if ( unlikely(rc) )
                 {
                     if ( rc == -EINTR )
                         rc = -ERESTART;
                     else if ( rc != -ERESTART )
-                        MEM_LOG("Error while installing new mfn %lx",
-                                op.arg1.mfn);
+                        MEM_LOG("Error %d while installing new mfn %lx",
+                                rc, op.arg1.mfn);
                     break;
                 }
                 if ( VM_ASSIST(d, m2p_strict) && !paging_mode_refcounts(d) )
@@ -3248,7 +3245,6 @@ long do_mmuext_op(
                         /* fallthrough */
                     case -ERESTART:
                         curr->arch.old_guest_table = page;
-                        okay = 0;
                         break;
                     default:
                         BUG_ON(rc);
@@ -3258,14 +3254,14 @@ long do_mmuext_op(
 
             break;
         }
-        
+
         case MMUEXT_TLB_FLUSH_LOCAL:
             if ( likely(d == pg_owner) )
                 flush_tlb_local();
             else
                 rc = -EPERM;
             break;
-    
+
         case MMUEXT_INVLPG_LOCAL:
             if ( unlikely(d != pg_owner) )
                 rc = -EPERM;
@@ -3342,7 +3338,7 @@ long do_mmuext_op(
             else
             {
                 MEM_LOG("Non-physdev domain tried to FLUSH_CACHE_GLOBAL");
-                okay = 0;
+                rc = -EINVAL;
             }
             break;
 
@@ -3356,13 +3352,13 @@ long do_mmuext_op(
             else if ( paging_mode_external(d) )
             {
                 MEM_LOG("ignoring SET_LDT hypercall from external domain");
-                okay = 0;
+                rc = -EINVAL;
             }
             else if ( ((ptr & (PAGE_SIZE - 1)) != 0) || !__addr_ok(ptr) ||
                       (ents > 8192) )
             {
-                okay = 0;
                 MEM_LOG("Bad args to SET_LDT: ptr=%lx, ents=%lx", ptr, ents);
+                rc = -EINVAL;
             }
             else if ( (curr->arch.pv_vcpu.ldt_ents != ents) ||
                       (curr->arch.pv_vcpu.ldt_base != ptr) )
@@ -3385,7 +3381,7 @@ long do_mmuext_op(
                 if ( page )
                     put_page(page);
                 MEM_LOG("Error while clearing mfn %lx", op.arg1.mfn);
-                okay = 0;
+                rc = -EINVAL;
                 break;
             }
 
@@ -3406,15 +3402,16 @@ long do_mmuext_op(
                                          P2M_ALLOC);
             if ( unlikely(!src_page) )
             {
-                okay = 0;
                 MEM_LOG("Error while copying from mfn %lx", op.arg2.src_mfn);
+                rc = -EINVAL;
                 break;
             }
 
             dst_page = get_page_from_gfn(pg_owner, op.arg1.mfn, NULL,
                                          P2M_ALLOC);
-            okay = (dst_page && get_page_type(dst_page, PGT_writable_page));
-            if ( unlikely(!okay) )
+            rc = (dst_page &&
+                  get_page_type(dst_page, PGT_writable_page)) ? 0 : -EINVAL;
+            if ( unlikely(rc) )
             {
                 put_page(src_page);
                 if ( dst_page )
@@ -3443,7 +3440,7 @@ long do_mmuext_op(
             else if ( mfn & (L1_PAGETABLE_ENTRIES-1) )
             {
                 MEM_LOG("Unaligned superpage reference mfn %lx", mfn);
-                okay = 0;
+                rc = -EINVAL;
             }
             else if ( !opt_allow_superpage )
             {
@@ -3464,7 +3461,7 @@ long do_mmuext_op(
             else if ( mfn & (L1_PAGETABLE_ENTRIES-1) )
             {
                 MEM_LOG("Unaligned superpage reference mfn %lx", mfn);
-                okay = 0;
+                rc = -EINVAL;
             }
             else if ( !opt_allow_superpage )
             {
@@ -3483,8 +3480,6 @@ long do_mmuext_op(
         }
 
  done:
-        if ( unlikely(!okay) && !rc )
-            rc = -EINVAL;
         if ( unlikely(rc) )
             break;