Merge tag 'x86_tdx_for_6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git...

Merge tag 'x86_tdx_for_6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 TDX updates from Dave Hansen:
 "Avoid direct HLT instruction execution in TDX guests.

  TDX guests aren't expected to use the HLT instruction directly. It
  causes a virtualization exception (#VE). While the #VE _can_ be
  handled, the current handling is slow and buggy and the easiest thing
  is just to avoid HLT in the first place. Plus, the kernel already has
  paravirt infrastructure that makes it relatively painless.

  Make TDX guests require paravirt and add some TDX-specific paravirt
  handlers which avoid HLT in the normal halt routines. Also add a
  warning in case another HLT sneaks in.

  There was a report that this leads to a "major performance
  improvement" on specjbb2015, probably because of the extra #VE
  overhead or missed wakeups from the buggy HLT handling"

* tag 'x86_tdx_for_6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/tdx: Emit warning if IRQs are enabled during HLT #VE handling
  x86/tdx: Fix arch_safe_halt() execution for TDX VMs
  x86/paravirt: Move halt paravirt calls under CONFIG_PARAVIRT