[Xen-devel] [PATCH] linux/x86-64: kern_addr_valid() must not walk page tables mapping hypervisor space

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- a/arch/x86_64/mm/init-xen.c
+++ b/arch/x86_64/mm/init-xen.c
@@ -1160,6 +1160,19 @@ int kern_addr_valid(unsigned long addr)
        if (above != 0 && above != -1UL)
                return 0; 
        
+#ifdef CONFIG_XEN
+       /*
+        * Don't walk page tables for hypervisor addresses, but allow
+        * the M2P table to be accessed through e.g. /proc/kcore.
+        */
+       if (addr >= (unsigned long)machine_to_phys_mapping &&
+           addr < (unsigned long)(machine_to_phys_mapping +
+                                  (1UL << machine_to_phys_order)))
+               return 1;
+       if (addr >= HYPERVISOR_VIRT_START && addr < HYPERVISOR_VIRT_END)
+               return 0;
+#endif
+
        pgd = pgd_offset_k(addr);
        if (pgd_none(*pgd))
                return 0;

Attachment: xen-x86_64-kern_addr_valid.patch
Description: Text document

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