[Xen-devel] [RFC PATCH 41/84] x86/shim: map and unmap page tables in replace_va_mapping

[<hongyax@xxxxxxxxxx>]

From: Wei Liu <wei.liu2@xxxxxxxxxx>

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/arch/x86/pv/shim.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/pv/shim.c b/xen/arch/x86/pv/shim.c
index 324ca27f93..cf638fa965 100644
--- a/xen/arch/x86/pv/shim.c
+++ b/xen/arch/x86/pv/shim.c
@@ -167,15 +167,25 @@ static void __init replace_va_mapping(struct domain *d, 
l4_pgentry_t *l4start,
                                       unsigned long va, mfn_t mfn)
 {
     l4_pgentry_t *pl4e = l4start + l4_table_offset(va);
-    l3_pgentry_t *pl3e = l4e_to_l3e(*pl4e) + l3_table_offset(va);
-    l2_pgentry_t *pl2e = l3e_to_l2e(*pl3e) + l2_table_offset(va);
-    l1_pgentry_t *pl1e = l2e_to_l1e(*pl2e) + l1_table_offset(va);
-    struct page_info *page = mfn_to_page(l1e_get_mfn(*pl1e));
+    l3_pgentry_t *pl3e;
+    l2_pgentry_t *pl2e;
+    l1_pgentry_t *pl1e;
 
-    put_page_and_type(page);
+    pl3e = map_xen_pagetable_new(l4e_get_mfn(*pl4e));
+    pl3e += l3_table_offset(va);
+    pl2e = map_xen_pagetable_new(l3e_get_mfn(*pl3e));
+    pl2e += l2_table_offset(va);
+    pl1e = map_xen_pagetable_new(l2e_get_mfn(*pl2e));
+    pl1e += l1_table_offset(va);
+
+    put_page_and_type(mfn_to_page(l1e_get_mfn(*pl1e)));
 
     *pl1e = l1e_from_mfn(mfn, (!is_pv_32bit_domain(d) ? L1_PROT
                                                       : COMPAT_L1_PROT));
+
+    UNMAP_XEN_PAGETABLE_NEW(pl1e);
+    UNMAP_XEN_PAGETABLE_NEW(pl2e);
+    UNMAP_XEN_PAGETABLE_NEW(pl3e);
 }
 
 static void evtchn_reserve(struct domain *d, unsigned int port)
-- 
2.17.1


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