• David Vrabel's avatar
    x86/xen: do not identity map UNUSABLE regions in the machine E820 · 89ca702c
    David Vrabel authored
    commit 3bc38cbc
    
     upstream.
    
    If there are UNUSABLE regions in the machine memory map, dom0 will
    attempt to map them 1:1 which is not permitted by Xen and the kernel
    will crash.
    
    There isn't anything interesting in the UNUSABLE region that the dom0
    kernel needs access to so we can avoid making the 1:1 mapping and
    treat it as RAM.
    
    We only do this for dom0, as that is where tboot case shows up.
    A PV domU could have an UNUSABLE region in its pseudo-physical map
    and would need to be handled in another patch.
    
    This fixes a boot failure on hosts with tboot.
    
    tboot marks a region in the e820 map as unusable and the dom0 kernel
    would attempt to map this region and Xen does not permit unusable
    regions to be mapped by guests.
    
      (XEN)  0000000000000000 - 0000000000060000 (usable)
      (XEN)  0000000000060000 - 0000000000068000 (reserved)
      (XEN)  0000000000068000 - 000000000009e000 (usable)
      (XEN)  0000000000100000 - 0000000000800000 (usable)
      (XEN)  0000000000800000 - 0000000000972000 (unusable)
    
    tboot marked this region as unusable.
    
      (XEN)  0000000000972000 - 00000000cf200000 (usable)
      (XEN)  00000000cf200000 - 00000000cf38f000 (reserved)
      (XEN)  00000000cf38f000 - 00000000cf3ce000 (ACPI data)
      (XEN)  00000000cf3ce000 - 00000000d0000000 (reserved)
      (XEN)  00000000e0000000 - 00000000f0000000 (reserved)
      (XEN)  00000000fe000000 - 0000000100000000 (reserved)
      (XEN)  0000000100000000 - 0000000630000000 (usable)
    Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
    [v1: Altered the patch and description with domU's with UNUSABLE regions]
    Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
    89ca702c
setup.c 12 KB