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SubjectRe: [PATCH v4 00/16] x86: make pat and mtrr independent from each other
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On 04.10.22 10:10, Juergen Gross wrote:
> 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.
>
> 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(-)
>

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