xen/arm: p2m: Extend p2m_get_entry to return the value of bit[0] (valid bit)

With the recent changes, a P2M entry may be populated but may not be
valid. In some situation, it would be useful to know whether the entry
has been marked available to guest in order to perform a specific
action. So extend p2m_get_entry to return the value of bit[0] (valid bit).

Signed-off-by: Julien Grall <julien.grall@arm.com>
Acked-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

diff --git a/xen/arch/arm/mem_access.c b/xen/arch/arm/mem_access.c
index f911937ccf2a739e7d46c0c80ceefd5ba112bd1d..db49372a2ce5c2ffb53ec9214e31870058ad6836 100644 (file)
--- a/xen/arch/arm/mem_access.c
+++ b/xen/arch/arm/mem_access.c
@@ -71,7 +71,7 @@ static int __p2m_get_mem_access(struct domain *d, gfn_t gfn,
          * No setting was found in the Radix tree. Check if the
          * entry exists in the page-tables.
          */
-        mfn_t mfn = p2m_get_entry(p2m, gfn, NULL, NULL, NULL);
+        mfn_t mfn = p2m_get_entry(p2m, gfn, NULL, NULL, NULL, NULL);
 
         if ( mfn_eq(mfn, INVALID_MFN) )
             return -ESRCH;
@@ -200,7 +200,7 @@ p2m_mem_access_check_and_get_page(vaddr_t gva, unsigned long flag,
      * We had a mem_access permission limiting the access, but the page type
      * could also be limiting, so we need to check that as well.
      */
-    mfn = p2m_get_entry(p2m, gfn, &t, NULL, NULL);
+    mfn = p2m_get_entry(p2m, gfn, &t, NULL, NULL, NULL);
     if ( mfn_eq(mfn, INVALID_MFN) )
         goto err;
 
@@ -406,7 +406,7 @@ long p2m_set_mem_access(struct domain *d, gfn_t gfn, uint32_t nr,
           gfn = gfn_next_boundary(gfn, order) )
     {
         p2m_type_t t;
-        mfn_t mfn = p2m_get_entry(p2m, gfn, &t, NULL, &order);
+        mfn_t mfn = p2m_get_entry(p2m, gfn, &t, NULL, &order, NULL);
 
 
         if ( !mfn_eq(mfn, INVALID_MFN) )

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 4e0ddbf70bef817c7dbac32511bd340097a521bf..c71322656182c44ebff5b6462c2e83888af19a16 100644 (file)
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -298,10 +298,14 @@ static int p2m_next_level(struct p2m_domain *p2m, bool read_only,
  *
  * If the entry is not present, INVALID_MFN will be returned and the
  * page_order will be set according to the order of the invalid range.
+ *
+ * valid will contain the value of bit[0] (e.g valid bit) of the
+ * entry.
  */
 mfn_t p2m_get_entry(struct p2m_domain *p2m, gfn_t gfn,
                     p2m_type_t *t, p2m_access_t *a,
-                    unsigned int *page_order)
+                    unsigned int *page_order,
+                    bool *valid)
 {
     paddr_t addr = gfn_to_gaddr(gfn);
     unsigned int level = 0;
@@ -326,6 +330,9 @@ mfn_t p2m_get_entry(struct p2m_domain *p2m, gfn_t gfn,
 
     *t = p2m_invalid;
 
+    if ( valid )
+        *valid = false;
+
     /* XXX: Check if the mapping is lower than the mapped gfn */
 
     /* This gfn is higher than the highest the p2m map currently holds */
@@ -371,6 +378,9 @@ mfn_t p2m_get_entry(struct p2m_domain *p2m, gfn_t gfn,
          * to the GFN.
          */
         mfn = mfn_add(mfn, gfn_x(gfn) & ((1UL << level_orders[level]) - 1));
+
+        if ( valid )
+            *valid = lpae_is_valid(entry);
     }
 
 out_unmap:
@@ -389,7 +399,7 @@ mfn_t p2m_lookup(struct domain *d, gfn_t gfn, p2m_type_t *t)
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
 
     p2m_read_lock(p2m);
-    mfn = p2m_get_entry(p2m, gfn, t, NULL, NULL);
+    mfn = p2m_get_entry(p2m, gfn, t, NULL, NULL, NULL);
     p2m_read_unlock(p2m);
 
     return mfn;
@@ -1471,7 +1481,7 @@ int relinquish_p2m_mapping(struct domain *d)
     for ( ; gfn_x(start) < gfn_x(end);
           start = gfn_next_boundary(start, order) )
     {
-        mfn_t mfn = p2m_get_entry(p2m, start, &t, NULL, &order);
+        mfn_t mfn = p2m_get_entry(p2m, start, &t, NULL, &order, NULL);
 
         count++;
         /*
@@ -1534,7 +1544,7 @@ int p2m_cache_flush_range(struct domain *d, gfn_t start, gfn_t end)
 
     for ( ; gfn_x(start) < gfn_x(end); start = next_gfn )
     {
-        mfn_t mfn = p2m_get_entry(p2m, start, &t, NULL, &order);
+        mfn_t mfn = p2m_get_entry(p2m, start, &t, NULL, &order, NULL);
 
         next_gfn = gfn_next_boundary(start, order);
 

diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index 5858f97e9c2a1da00664b7f6aad3adb1a3f9a4cb..7c1d930b1db55e180f46b059d1a816fb3587dcf6 100644 (file)
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -213,7 +213,8 @@ mfn_t p2m_lookup(struct domain *d, gfn_t gfn, p2m_type_t *t);
  */
 mfn_t p2m_get_entry(struct p2m_domain *p2m, gfn_t gfn,
                     p2m_type_t *t, p2m_access_t *a,
-                    unsigned int *page_order);
+                    unsigned int *page_order,
+                    bool *valid);
 
 /*
  * Direct set a p2m entry: only for use by the P2M code.