[PATCH v4 00/10] Make PAT handling less brittle

[Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>]

While working on Qubes OS Marek found out that there were some PAT hacks
in the Linux i195 driver.  I decided to make Xen use Linux’s PAT to see
if it solved the graphics glitches that were observed; it did.  This
required a substantial amount of preliminary work that is useful even
without using Linux’s PAT.

Patches 1 through 9 are the preliminary work and I would like them to be
accepted into upstream Xen.  Patch 9 does break ABI by rejecting the
unused PAT entries, but this will only impact buggy PV guests and can be
disabled with a Xen command-line option.  Patch 10 actually switches to
Linux’s PAT and is NOT intended to be merged (at least for now) as it
would at a minimum break migration of PV guests from hosts that do not
have the patch.

This patch series is shorter than v3 as two of the patches have already
been accepted into staging.  Only patches 9 and 10 actually change Xen’s
observable behavior.  Patches 1, 2, and 7 are prerequisites, and patches
3 through 6 are cleanups.  Patch 8 makes changing the PAT much less
error-prone, as problems with the PAT or with the associated _PAGE_*
constants will be detected at compile time.

Demi Marie Obenour (10):
  x86: Add memory type constants
  x86/mm: Avoid hard-coding PAT in get_page_from_l1e()
  x86: Replace PAT_* with X86_MT_*
  x86: Replace MTRR_* constants with X86_MT_* constants
  x86: Replace EPT_EMT_* constants with X86_MT_*
  x86: Remove MEMORY_NUM_TYPES and NO_HARDCODE_MEM_TYPE
  x86: Derive XEN_MSR_PAT from its individual entries
  x86/mm: make code robust to future PAT changes
  x86/mm: Reject invalid cacheability in PV guests by default
  x86: Use Linux's PAT

 xen/arch/x86/cpu/mtrr/generic.c         |  10 +--
 xen/arch/x86/cpu/mtrr/main.c            |  26 +++---
 xen/arch/x86/e820.c                     |   4 +-
 xen/arch/x86/hvm/hvm.c                  |  12 +--
 xen/arch/x86/hvm/mtrr.c                 | 100 ++++++++++++------------
 xen/arch/x86/hvm/vmx/vmcs.c             |   2 +-
 xen/arch/x86/hvm/vmx/vmx.c              |  18 ++---
 xen/arch/x86/include/asm/hvm/vmx/vmcs.h |   2 +-
 xen/arch/x86/include/asm/hvm/vmx/vmx.h  |   9 ---
 xen/arch/x86/include/asm/mtrr.h         |  22 +-----
 xen/arch/x86/include/asm/page.h         |   4 +-
 xen/arch/x86/include/asm/processor.h    |  19 ++++-
 xen/arch/x86/include/asm/x86-defns.h    |  11 +++
 xen/arch/x86/mm.c                       |  84 ++++++++++++++++++--
 xen/arch/x86/mm/hap/nested_ept.c        |   4 +-
 xen/arch/x86/mm/p2m-ept.c               |  51 ++++++------
 xen/arch/x86/mm/shadow/multi.c          |   8 +-
 17 files changed, 227 insertions(+), 159 deletions(-)

-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab