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 up - 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.
Changes in V2: - complete rework of the patches based on comments by Boris Petkov - added several patches to the series
Juergen Gross (10): x86/mtrr: fix MTRR fixup on APs x86/mtrr: remove unused cyrix_set_all() function x86/mtrr: replace use_intel() with a local flag 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: 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
arch/x86/include/asm/cacheinfo.h | 14 +++ arch/x86/include/asm/memtype.h | 5 +- arch/x86/include/asm/mtrr.h | 12 +-- arch/x86/kernel/cpu/cacheinfo.c | 159 +++++++++++++++++++++++++++++ arch/x86/kernel/cpu/common.c | 3 +- arch/x86/kernel/cpu/mtrr/cyrix.c | 34 ------ arch/x86/kernel/cpu/mtrr/generic.c | 120 ++++------------------ arch/x86/kernel/cpu/mtrr/mtrr.c | 158 +++++----------------------- arch/x86/kernel/cpu/mtrr/mtrr.h | 5 - 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 +- 13 files changed, 274 insertions(+), 389 deletions(-)