[Xen-devel] [PATCH for-4.12 v3 1/8] xen/arm: p2m: Introduce p2m_get_page_from_gfn

[Julien Grall <julien.grall@xxxxxxx>]

In a follow-up patch, we will need to handle get_page_from_gfn
differently for DOMID_XEN. To keep the code simple move the current
content in a new separate helper p2m_get_page_from_gfn.

Note the new helper is not anymore a static inline function as the helper
is quite complex.

Finally, take the opportunity to use typesafe gfn as the change is
minor.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
Reviewed-by: Andrii Anisov <andrii_anisov@xxxxxxxx>
Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

---
    Changes in v3:
        - Fix typeos
        - Add Stefano's reviewed-by
        - Fix coding style

    Changes in v2:
        - Add Andrii's reviewed-by
---
 xen/arch/arm/p2m.c        | 33 +++++++++++++++++++++++++++++++++
 xen/include/asm-arm/p2m.h | 33 ++++-----------------------------
 2 files changed, 37 insertions(+), 29 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 2b5e43f50a..7ae5b29699 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -406,6 +406,39 @@ mfn_t p2m_lookup(struct domain *d, gfn_t gfn, p2m_type_t 
*t)
     return mfn;
 }
 
+struct page_info *p2m_get_page_from_gfn(struct domain *d, gfn_t gfn,
+                                        p2m_type_t *t)
+{
+    struct page_info *page;
+    p2m_type_t p2mt;
+    mfn_t mfn = p2m_lookup(d, gfn, &p2mt);
+
+    if ( t )
+        *t = p2mt;
+
+    if ( !p2m_is_any_ram(p2mt) )
+        return NULL;
+
+    if ( !mfn_valid(mfn) )
+        return NULL;
+
+    page = mfn_to_page(mfn);
+
+    /*
+     * get_page won't work on foreign mapping because the page doesn't
+     * belong to the current domain.
+     */
+    if ( p2m_is_foreign(p2mt) )
+    {
+        struct domain *fdom = page_get_owner_and_reference(page);
+        ASSERT(fdom != NULL);
+        ASSERT(fdom != d);
+        return page;
+    }
+
+    return get_page(page, d) ? page : NULL;
+}
+
 int guest_physmap_mark_populate_on_demand(struct domain *d,
                                           unsigned long gfn,
                                           unsigned int order)
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index 01cd3ee4b5..4db8e8709d 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -289,38 +289,13 @@ typedef unsigned int p2m_query_t;
 #define P2M_ALLOC    (1u<<0)   /* Populate PoD and paged-out entries */
 #define P2M_UNSHARE  (1u<<1)   /* Break CoW sharing */
 
+struct page_info *p2m_get_page_from_gfn(struct domain *d, gfn_t gfn,
+                                        p2m_type_t *t);
+
 static inline struct page_info *get_page_from_gfn(
     struct domain *d, unsigned long gfn, p2m_type_t *t, p2m_query_t q)
 {
-    struct page_info *page;
-    p2m_type_t p2mt;
-    mfn_t mfn = p2m_lookup(d, _gfn(gfn), &p2mt);
-
-    if (t)
-        *t = p2mt;
-
-    if ( !p2m_is_any_ram(p2mt) )
-        return NULL;
-
-    if ( !mfn_valid(mfn) )
-        return NULL;
-    page = mfn_to_page(mfn);
-
-    /*
-     * get_page won't work on foreign mapping because the page doesn't
-     * belong to the current domain.
-     */
-    if ( p2m_is_foreign(p2mt) )
-    {
-        struct domain *fdom = page_get_owner_and_reference(page);
-        ASSERT(fdom != NULL);
-        ASSERT(fdom != d);
-        return page;
-    }
-
-    if ( !get_page(page, d) )
-        return NULL;
-    return page;
+    return p2m_get_page_from_gfn(d, _gfn(gfn), t);
 }
 
 int get_page_type(struct page_info *page, unsigned long type);
-- 
2.11.0


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