x86/P2M: p2m_change_type() should pass on error from p2m_set_entry()

Modify the function's name to help eventual backports involving this
function, and in one case where this is trivially possible also stop
ignoring its return value.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Tim Deegan <tim@xen.org>

diff --git a/xen/arch/x86/cpu/mcheck/vmce.c b/xen/arch/x86/cpu/mcheck/vmce.c
index c83375e5ddac8eafe33de649b07f0293e387717e..3f3ef3cc63c88bf9d9f3016d546338489aa5abe0 100644 (file)
--- a/xen/arch/x86/cpu/mcheck/vmce.c
+++ b/xen/arch/x86/cpu/mcheck/vmce.c
@@ -444,8 +444,7 @@ int unmmap_broken_page(struct domain *d, mfn_t mfn, unsigned long gfn)
     if ( p2m_to_mask(pt) & P2M_UNMAP_TYPES)
     {
         ASSERT(mfn_x(r_mfn) == mfn_x(mfn));
-        p2m_change_type(d, gfn, pt, p2m_ram_broken);
-        rc = 0;
+        rc = p2m_change_type_one(d, gfn, pt, p2m_ram_broken);
     }
     put_gfn(d, gfn);
 

diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index fbdc8e61079751760c02287667e7bba657f0a8a7..ff24e0e9098606f53b715f37d2b079f07b9d41dc 100644 (file)
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1333,9 +1333,10 @@ long arch_do_domctl(
         unsigned long pfn = domctl->u.set_broken_page_p2m.pfn;
         mfn_t mfn = get_gfn_query(d, pfn, &pt);
 
-        if ( unlikely(!mfn_valid(mfn_x(mfn)) || !p2m_is_ram(pt) ||
-                     (p2m_change_type(d, pfn, pt, p2m_ram_broken) != pt)) )
+        if ( unlikely(!mfn_valid(mfn_x(mfn))) || unlikely(!p2m_is_ram(pt)) )
             ret = -EINVAL;
+        else
+            ret = p2m_change_type_one(d, pfn, pt, p2m_ram_broken);
 
         put_gfn(d, pfn);
     }

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index da220bf0fe8ddb5c3d4fe0109151735066f88262..b697b6c2c9e64af5052ddf175e8c1177018c1cfe 100644 (file)
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -1698,7 +1698,7 @@ int hvm_hap_nested_page_fault(paddr_t gpa,
         if ( access_w )
         {
             paging_mark_dirty(v->domain, mfn_x(mfn));
-            p2m_change_type(v->domain, gfn, p2m_ram_logdirty, p2m_ram_rw);
+            p2m_change_type_one(v->domain, gfn, p2m_ram_logdirty, p2m_ram_rw);
         }
         rc = 1;
         goto out_put_gfn;
@@ -4540,7 +4540,7 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
         while ( a.nr > start_iter )
         {
             unsigned long pfn = a.first_pfn + start_iter;
-            p2m_type_t t, nt;
+            p2m_type_t t;
 
             get_gfn_unshare(d, pfn, &t);
             if ( p2m_is_paging(t) )
@@ -4563,16 +4563,10 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
                 goto param_fail4;
             }
 
-            nt = p2m_change_type(d, pfn, t, memtype[a.hvmmem_type]);
-            if ( nt != t )
-            {
-                put_gfn(d, pfn);
-                printk(XENLOG_G_WARNING
-                       "d%d: GFN %#lx type changed from %d to %d while trying to change it to %d\n",
-                       d->domain_id, pfn, t, nt, memtype[a.hvmmem_type]);
-                goto param_fail4;
-            }
+            rc = p2m_change_type_one(d, pfn, t, memtype[a.hvmmem_type]);
             put_gfn(d, pfn);
+            if ( rc )
+                goto param_fail4;
 
             /* Check for continuation if it's not the last interation */
             if ( a.nr > ++start_iter && !(start_iter & HVMOP_op_mask) &&

diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index 61f0b22b193e89d81993cba1644588ee731ac7b3..3e627f0d86992e6bb93a9ecb7f66fec702f284d4 100644 (file)
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -913,7 +913,7 @@ int mem_sharing_nominate_page(struct domain *d,
     }
 
     /* Change the p2m type, should never fail with p2m locked. */
-    BUG_ON(p2m_change_type(d, gfn, p2mt, p2m_ram_shared) != p2mt);
+    BUG_ON(p2m_change_type_one(d, gfn, p2mt, p2m_ram_shared));
 
     /* Account for this page. */
     atomic_inc(&nr_shared_mfns);
@@ -1236,8 +1236,7 @@ int __mem_sharing_unshare_page(struct domain *d,
     put_page_and_type(old_page);
 
 private_page_found:    
-    if ( p2m_change_type(d, gfn, p2m_ram_shared, p2m_ram_rw) != 
-                                                p2m_ram_shared ) 
+    if ( p2m_change_type_one(d, gfn, p2m_ram_shared, p2m_ram_rw) )
     {
         gdprintk(XENLOG_ERR, "Could not change p2m type d %hu gfn %lx.\n", 
                                 d->domain_id, gfn);

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index afff8dba201f66972c7f57faeed6c375a965075f..1d1dd1b7290d1f4e27c7871cf276c72951cadd30 100644 (file)
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -704,27 +704,33 @@ out:
 }
 
 
-/* Modify the p2m type of a single gfn from ot to nt, returning the 
- * entry's previous type.  Resets the access permissions. */
-p2m_type_t p2m_change_type(struct domain *d, unsigned long gfn, 
-                           p2m_type_t ot, p2m_type_t nt)
+/*
+ * Modify the p2m type of a single gfn from ot to nt.
+ * Returns: 0 for success, -errno for failure.
+ * Resets the access permissions.
+ */
+int p2m_change_type_one(struct domain *d, unsigned long gfn,
+                       p2m_type_t ot, p2m_type_t nt)
 {
     p2m_access_t a;
     p2m_type_t pt;
     mfn_t mfn;
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
+    int rc;
 
     BUG_ON(p2m_is_grant(ot) || p2m_is_grant(nt));
 
     gfn_lock(p2m, gfn, 0);
 
     mfn = p2m->get_entry(p2m, gfn, &pt, &a, 0, NULL);
-    if ( pt == ot )
-        p2m_set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, nt, p2m->default_access);
+    rc = likely(pt == ot)
+         ? p2m_set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, nt,
+                         p2m->default_access)
+         : -EBUSY;
 
     gfn_unlock(p2m, gfn, 0);
 
-    return pt;
+    return rc;
 }
 
 /* Modify the p2m type of a range of gfns from ot to nt. */

diff --git a/xen/arch/x86/mm/paging.c b/xen/arch/x86/mm/paging.c
index f956aa52083eece5ffdba8e9eb432cdc2a04984c..9e9a11b561ff35122688d75127c772d7a0680a56 100644 (file)
--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -469,12 +469,8 @@ void paging_log_dirty_range(struct domain *d,
     p2m_lock(p2m);
 
     for ( i = 0, pfn = begin_pfn; pfn < begin_pfn + nr; i++, pfn++ )
-    {
-        p2m_type_t pt;
-        pt = p2m_change_type(d, pfn, p2m_ram_rw, p2m_ram_logdirty);
-        if ( pt == p2m_ram_rw )
+        if ( !p2m_change_type_one(d, pfn, p2m_ram_rw, p2m_ram_logdirty) )
             dirty_bitmap[i >> 3] |= (1 << (i & 7));
-    }
 
     p2m_unlock(p2m);
 

diff --git a/xen/drivers/passthrough/amd/iommu_guest.c b/xen/drivers/passthrough/amd/iommu_guest.c
index 477de208bfc9f757e4467e6e8a9ff192903530b9..f638bef542bcf0a1947571aacd060d3bfa8e8bea 100644 (file)
--- a/xen/drivers/passthrough/amd/iommu_guest.c
+++ b/xen/drivers/passthrough/amd/iommu_guest.c
@@ -823,7 +823,7 @@ int guest_iommu_set_base(struct domain *d, uint64_t base)
         unsigned long gfn = base + i;
 
         get_gfn_query(d, gfn, &t);
-        p2m_change_type(d, gfn, t, p2m_mmio_dm);
+        p2m_change_type_one(d, gfn, t, p2m_mmio_dm);
         put_gfn(d, gfn);
     }
 

diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 9d48775fb48477f3c7ca673d1c13d4fc2db3a40f..027f01100b9a6f032f56dee4eaaa305214aac266 100644 (file)
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -519,8 +519,8 @@ void p2m_change_type_range(struct domain *d,
                            p2m_type_t ot, p2m_type_t nt);
 
 /* Compare-exchange the type of a single p2m entry */
-p2m_type_t p2m_change_type(struct domain *d, unsigned long gfn,
-                           p2m_type_t ot, p2m_type_t nt);
+int p2m_change_type_one(struct domain *d, unsigned long gfn,
+                        p2m_type_t ot, p2m_type_t nt);
 
 /* Report a change affecting memory types. */
 void p2m_memory_type_changed(struct domain *d);