Thread (49 messages) 49 messages, 7 authors, 2021-11-16

Re: [PATCH v2 02/15] x86/cpu: Extract cpuid helpers to arch-independent

From: "Winiarska, Iwona" <iwona.winiarska@intel.com>
Date: 2021-10-11 19:33:09
Also in: linux-aspeed, linux-devicetree, linux-doc, linux-hwmon, lkml, openbmc

On Mon, 2021-10-04 at 21:08 +0200, Borislav Petkov wrote:
On Tue, Aug 03, 2021 at 01:31:21PM +0200, Iwona Winiarska wrote:
quoted
Baseboard management controllers (BMC) often run Linux but are usually
implemented with non-X86 processors. They can use PECI to access package
config space (PCS) registers on the host CPU and since some information,
e.g. figuring out the core count, can be obtained using different
registers on different CPU generations, they need to decode the family
and model.

The format of Package Identifier PCS register that describes CPUID
information has the same layout as CPUID_1.EAX, so let's allow to reuse
cpuid helpers by making it available for other architectures as well.

Signed-off-by: Iwona Winiarska <iwona.winiarska@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Dan Williams <redacted>
---
 MAINTAINERS                      | 1 +
 arch/x86/Kconfig                 | 1 +
 arch/x86/include/asm/cpu.h       | 3 ---
 arch/x86/include/asm/microcode.h | 2 +-
 arch/x86/kvm/cpuid.h             | 3 ++-
 arch/x86/lib/Makefile            | 2 +-
 drivers/edac/mce_amd.c           | 3 +--
 include/linux/x86/cpu.h          | 9 +++++++++
 lib/Kconfig                      | 4 ++++
 lib/Makefile                     | 2 ++
 lib/x86/Makefile                 | 3 +++
 {arch/x86/lib => lib/x86}/cpu.c  | 2 +-
 12 files changed, 26 insertions(+), 9 deletions(-)
 create mode 100644 include/linux/x86/cpu.h
 create mode 100644 lib/x86/Makefile
 rename {arch/x86/lib => lib/x86}/cpu.c (95%)
AFAICT, all that churn is done for x86_family() and x86_model() which
are used *exactly* *once* and which are almost trivial anyway.
Correct.
What's wrong with simply computing the family and model "by hand", so to
speak, in peci_device_info_init() and do away with that diffstat

 12 files changed, 26 insertions(+), 9 deletions(-)

?
Nothing wrong - just a trade-off between churn and keeping things tidy and not
duplicated, similar to patch 1.
And just like in patch 1, if you have a strong opinion against it - we can
duplicate. 

Thanks
-Iwona

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