[PATCH v4 00/16] x86: make pat and mtrr independent from each other

From: Juergen Gross
Date: Tue Oct 04 2022 - 04:12:07 EST

Today PAT can't be used without MTRR being available, unless MTRR is at
least configured via CONFIG_MTRR and the system is running as Xen PV
guest. In this case PAT is automatically available via the hypervisor,
but the PAT MSR can't be modified by the kernel and MTRR is disabled.

The same applies to a kernel built with no MTRR support: it won't
allow to use the PAT MSR, even if there is no technical reason for
that, other than setting up PAT on all cpus the same way (which is a
requirement of the processor's cache management) is relying on some
MTRR specific code.

Fix all of that by:

- moving the function needed by PAT from MTRR specific code one level
- reworking the init sequences of MTRR and PAT to be more similar to
each other without calling PAT from MTRR code
- removing the dependency of PAT on MTRR

While working on that I discovered two minor bugs in MTRR code, which
are fixed, too.

There is some more cleanup done reducing code size.

Changes in V4:
- new patches 10, 14, 15, 16
- split up old patch 4 into 3 patches
- addressed comments

Changes in V3:
- replace patch 1 by just adding a comment

Changes in V2:
- complete rework of the patches based on comments by Boris Petkov
- added several patches to the series

Juergen Gross (16):
x86/mtrr: add comment for set_mtrr_state() serialization
x86/mtrr: remove unused cyrix_set_all() function
x86/mtrr: replace use_intel() with a local flag
x86/mtrr: rename prepare_set() and post_set()
x86/mtrr: split MTRR specific handling from cache dis/enabling
x86: move some code out of arch/x86/kernel/cpu/mtrr
x86/mtrr: split generic_set_all()
x86/mtrr: remove set_all callback from struct mtrr_ops
x86/mtrr: simplify mtrr_bp_init()
x86/mtrr: get rid of mtrr_enabled bool
x86/mtrr: let cache_aps_delayed_init replace mtrr_aps_delayed_init
x86/mtrr: add a stop_machine() handler calling only cache_cpu_init()
x86: decouple pat and mtrr handling
x86: switch cache_ap_init() to hotplug callback
x86: do MTRR/PAT setup on all secondary CPUs in parallel
x86/mtrr: simplify mtrr_ops initialization

arch/x86/include/asm/cacheinfo.h | 18 +++
arch/x86/include/asm/memtype.h | 5 +-
arch/x86/include/asm/mtrr.h | 13 +-
arch/x86/kernel/cpu/cacheinfo.c | 168 ++++++++++++++++++++++++++
arch/x86/kernel/cpu/common.c | 2 +-
arch/x86/kernel/cpu/mtrr/amd.c | 8 +-
arch/x86/kernel/cpu/mtrr/centaur.c | 8 +-
arch/x86/kernel/cpu/mtrr/cyrix.c | 42 +------
arch/x86/kernel/cpu/mtrr/generic.c | 127 +++-----------------
arch/x86/kernel/cpu/mtrr/mtrr.c | 185 ++++-------------------------
arch/x86/kernel/cpu/mtrr/mtrr.h | 20 ++--
arch/x86/kernel/setup.c | 14 +--
arch/x86/kernel/smpboot.c | 9 +-
arch/x86/mm/pat/memtype.c | 127 ++++++--------------
arch/x86/power/cpu.c | 3 +-
include/linux/cpuhotplug.h | 1 +
16 files changed, 298 insertions(+), 452 deletions(-)