[Xen-devel] [PATCH v1] x86/mm: Make change_type_range return error

[Alexandru Stefan ISAILA <aisaila@xxxxxxxxxxxxxxx>]

At this moment change_type_range() prints a warning in case end >
host_max_pfn. While this is unlikely to happen the function should
return a error and propagate it to the caller, hap_track_dirty_vram()

This patch makes change_type_range() return -EINVAL or 0 if all is ok.

Signed-off-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/mm/hap/hap.c | 12 ++++++++----
 xen/arch/x86/mm/p2m.c     | 32 ++++++++++++++++++++------------
 xen/include/asm-x86/p2m.h |  6 +++---
 3 files changed, 31 insertions(+), 19 deletions(-)

diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c
index 412a442b6a..b113c3154b 100644
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -108,15 +108,19 @@ int hap_track_dirty_vram(struct domain *d,
             paging_unlock(d);
 
             if ( oend > ostart )
-                p2m_change_type_range(d, ostart, oend,
-                                      p2m_ram_logdirty, p2m_ram_rw);
+                rc = p2m_change_type_range(d, ostart, oend,
+                                           p2m_ram_logdirty, p2m_ram_rw);
+            if ( rc )
+                goto out;
 
             /*
              * Switch vram to log dirty mode, either by setting l1e entries of
              * P2M table to be read-only, or via hardware-assisted log-dirty.
              */
-            p2m_change_type_range(d, begin_pfn, begin_pfn + nr,
-                                  p2m_ram_rw, p2m_ram_logdirty);
+            rc = p2m_change_type_range(d, begin_pfn, begin_pfn + nr,
+                                       p2m_ram_rw, p2m_ram_logdirty);
+            if ( rc )
+                goto out;
 
             flush_tlb_mask(d->dirty_cpumask);
 
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 9e81a30cc4..27697d5a77 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1028,7 +1028,7 @@ int p2m_change_type_one(struct domain *d, unsigned long 
gfn_l,
 }
 
 /* Modify the p2m type of [start, end_exclusive) from ot to nt. */
-static void change_type_range(struct p2m_domain *p2m,
+static int change_type_range(struct p2m_domain *p2m,
                               unsigned long start, unsigned long end_exclusive,
                               p2m_type_t ot, p2m_type_t nt)
 {
@@ -1053,15 +1053,11 @@ static void change_type_range(struct p2m_domain *p2m,
      * This should be revisited later, but for now post a warning.
      */
     if ( unlikely(end > host_max_pfn) )
-    {
-        printk(XENLOG_G_WARNING "Dom%d logdirty rangeset clipped to 
max_mapped_pfn\n",
-               d->domain_id);
-        end = invalidate_end = host_max_pfn;
-    }
+        return -EINVAL;
 
     /* If the requested range is out of scope, return doing nothing. */
     if ( start > end )
-        return;
+        return 0;
 
     if ( p2m_is_altp2m(p2m) )
         invalidate_end = min(invalidate_end, max_pfn);
@@ -1115,13 +1111,16 @@ static void change_type_range(struct p2m_domain *p2m,
                rc, d->domain_id);
         domain_crash(d);
     }
+
+    return 0;
 }
 
-void p2m_change_type_range(struct domain *d,
-                           unsigned long start, unsigned long end,
-                           p2m_type_t ot, p2m_type_t nt)
+int p2m_change_type_range(struct domain *d,
+                          unsigned long start, unsigned long end,
+                          p2m_type_t ot, p2m_type_t nt)
 {
     struct p2m_domain *hostp2m = p2m_get_hostp2m(d);
+    int rc = 0;
 
     ASSERT(ot != nt);
     ASSERT(p2m_is_changeable(ot) && p2m_is_changeable(nt));
@@ -1129,7 +1128,10 @@ void p2m_change_type_range(struct domain *d,
     p2m_lock(hostp2m);
     hostp2m->defer_nested_flush = 1;
 
-    change_type_range(hostp2m, start, end, ot, nt);
+    rc = change_type_range(hostp2m, start, end, ot, nt);
+
+    if ( rc )
+        goto out;
 
 #ifdef CONFIG_HVM
     if ( unlikely(altp2m_active(d)) )
@@ -1142,8 +1144,11 @@ void p2m_change_type_range(struct domain *d,
                 struct p2m_domain *altp2m = d->arch.altp2m_p2m[i];
 
                 p2m_lock(altp2m);
-                change_type_range(altp2m, start, end, ot, nt);
+                rc = change_type_range(altp2m, start, end, ot, nt);
                 p2m_unlock(altp2m);
+
+                if ( rc )
+                    goto out;
             }
     }
 #endif
@@ -1151,7 +1156,10 @@ void p2m_change_type_range(struct domain *d,
     if ( nestedhvm_enabled(d) )
         p2m_flush_nestedp2m(d);
 
+out:
     p2m_unlock(hostp2m);
+
+    return rc;
 }
 
 /*
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 2801a8ccca..a118812025 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -613,9 +613,9 @@ void p2m_change_entry_type_global(struct domain *d,
                                   p2m_type_t ot, p2m_type_t nt);
 
 /* Change types across a range of p2m entries (start ... end-1) */
-void p2m_change_type_range(struct domain *d, 
-                           unsigned long start, unsigned long end,
-                           p2m_type_t ot, p2m_type_t nt);
+int p2m_change_type_range(struct domain *d,
+                          unsigned long start, unsigned long end,
+                          p2m_type_t ot, p2m_type_t nt);
 
 /* Compare-exchange the type of a single p2m entry */
 int p2m_change_type_one(struct domain *d, unsigned long gfn,
-- 
2.17.1

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