[PATCH v3 0/3] Introduce a REQUIRE_NX Kconfig option

[Alejandro Vallejo <alejandro.vallejo@xxxxxxxxx>]

v3:
  * Fixed a Gitlab CI breakage on older toolchains (patch 1)
  * Removed XD_DISABLE override logic from cpu/intel.c
  * Various style fixes to patch 2 (from Andrew's feedback)

This option hardens Xen by forcing it to write secure (NX-enhanced) PTEs
regardless of the runtime NX feature bit in boot_cpu_data. This prevents an
attacker with partial write support from affecting Xen's PTE generation
logic by overriding the NX feature flag. The patch asserts support for the
NX bit in PTEs at boot time and if so short-circuits the cpu_has_nx macro
to 1.

Alejandro Vallejo (3):
  tools: Add __AC() macro to common-macros.h
  x86/boot: Clear XD_DISABLE from the early boot path
  x86: Add Kconfig option to require NX bit support

 tools/include/xen-tools/common-macros.h |  3 ++
 tools/libs/light/libxl_internal.h       |  2 -
 tools/tests/x86_emulator/x86-emulate.h  |  3 --
 xen/arch/x86/Kconfig                    | 16 +++++++
 xen/arch/x86/boot/head.S                | 62 ++++++++++++++++++++++---
 xen/arch/x86/boot/trampoline.S          |  3 +-
 xen/arch/x86/cpu/intel.c                | 16 +++----
 xen/arch/x86/efi/efi-boot.h             |  9 ++++
 xen/arch/x86/include/asm/cpufeature.h   |  3 +-
 xen/arch/x86/include/asm/msr-index.h    |  2 +-
 xen/arch/x86/include/asm/x86-vendors.h  |  6 +--
 11 files changed, 98 insertions(+), 27 deletions(-)

-- 
2.34.1