[PATCH RESEND 0/3] Add restrictions for kexec/kdump jumping between 5-level and 4-level kernel

[Baoquan He]

This is a RESEND post.

The original v1 post can be found here:
http://lkml.kernel.org/r/20180829141624.13985-1-bhe@xxxxxxxxxx

It's trying to fix several corner case issues for kexec/kdump when
dynamic switching of paging mode is enabled in x86_64. Please click 
above link to check the details.

In v1, hpa raised concern that why the paging mode checking is not done
before kexec jumping, the discussion can be found here:

http://lkml.kernel.org/r/alpine.DEB.2.21.1809051002020.1416@xxxxxxxxxxxxxxxxxxxxxxx

As tglx said, it might be not doable for kdump since kdump kernel's
reserved crashkernel region only owns a portion of memory, may
be above 4G; and might be not safer to do paging mode checking and
switching thing after crash.

So resend this patchset.

Baoquan He (3):
  x86/boot: Add bit fields into xloadflags for 5-level kernel checking
  x86/kexec/64: Error out if try to jump to old 4-level kernel from
    5-level kernel
  x86/kdump/64: Change the upper limit of crashkernel reservation

 arch/x86/boot/header.S                | 12 +++++++++++-
 arch/x86/include/uapi/asm/bootparam.h |  2 ++
 arch/x86/kernel/kexec-bzimage64.c     |  5 +++++
 arch/x86/kernel/setup.c               | 18 ++++++++++++++----
 4 files changed, 32 insertions(+), 5 deletions(-)

-- 
2.13.6