Alternative XSA-286 fix, with far less of a performance hit.

v3:
 * Split into two patches, to try and make the TLB flushing in do_mmu_update()
   a tractable problem to solve.

Andrew Cooper (2):
  x86/pv: Drop FLUSH_TLB_GLOBAL in do_mmu_update() for XPTI
  x86/pv: Flush TLB in response to paging structure changes

 xen/arch/x86/mm.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 59 insertions(+), 10 deletions(-)

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2.11.0