[Xen-devel] [PATCH 2/2] x86: map portion of kexec crash area that is within the direct map area

[David Vrabel <david.vrabel@xxxxxxxxxx>]

From: David Vrabel <david.vrabel@xxxxxxxxxx>

map_domain_page() is used to temporarily map the crash area when
loading a kexec crash image.

If some or all of the crash area is within the direct map area then
this portion must have a direct mapping, otherwise map_domain_page()
(on non-debug builds) will return a direct map VA that is not actually
mapped.

Parts of the crash area outside the direct map area (i.e., above 5 TiB)
do not need and should not have such a mapping.

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
 xen/arch/x86/setup.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index f07ee2b..8e10bdf 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1097,9 +1097,17 @@ void __init __start_xen(unsigned long mbi_p)
                          mod[i].mod_start,
                          PFN_UP(mod[i].mod_end), PAGE_HYPERVISOR);
     }
-    map_pages_to_xen((unsigned long)__va(kexec_crash_area.start),
-                     kexec_crash_area.start >> PAGE_SHIFT,
-                     PFN_UP(kexec_crash_area.size), PAGE_HYPERVISOR);
+
+    if ( kexec_crash_area.size )
+    {
+        unsigned long s = PFN_DOWN(kexec_crash_area.start);
+        unsigned long e = min(s + PFN_UP(kexec_crash_area.size),
+                              PFN_UP(__pa(HYPERVISOR_VIRT_END - 1)));
+
+        map_pages_to_xen((unsigned long)__va(kexec_crash_area.start),
+                         s, e - s, PAGE_HYPERVISOR);
+    }
+
     xen_virt_end = ((unsigned long)_end + (1UL << L2_PAGETABLE_SHIFT) - 1) &
                    ~((1UL << L2_PAGETABLE_SHIFT) - 1);
     destroy_xen_mappings(xen_virt_end, XEN_VIRT_START + BOOTSTRAP_MAP_BASE);
-- 
1.7.2.5


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