mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
* [RESEND v1 0/3] x86/cpufeatures: Automatically generate required and disabled feature masks
@ 2024-05-09 20:53 Xin Li (Intel)
  2024-05-09 20:53 ` [RESEND v1 1/3] x86/cpufeatures: Add {required,disabled} feature configs Xin Li (Intel)
                   ` (2 more replies)
  0 siblings, 3 replies; 9+ messages in thread
From: Xin Li (Intel) @ 2024-05-09 20:53 UTC (permalink / raw)
  To: linux-kernel, linux-perf-users
  Cc: tglx, mingo, bp, dave.hansen, x86, hpa, will, peterz, akpm, acme,
	namhyung

This is a rebase and resend of: https://lore.kernel.org/lkml/20240201054629.3816748-1-xin@zytor.com/.

The x86 build process first generates required and disabled feature
masks based on current build config, and then uses these generated
masks to compile the source code. When a CPU feature is not enabled
in a build config, e.g., when CONFIG_X86_FRED=n, its feature disable
flag, i.e., DISABLE_FRED, needs to be properly defined and added to
a specific disabled CPU features mask in <asm/disabled-features.h>,
as the following patch does:
https://lore.kernel.org/all/20231205105030.8698-8-xin3.li@intel.com/.
As a result, the FRED feature bit is surely cleared in the generated
kernel binary when CONFIG_X86_FRED=n.

Recently there is another case to repeat the same exercise for the
AMD SEV-SNP CPU feature:
https://lore.kernel.org/all/20240126041126.1927228-2-michael.roth@amd.com/.
https://lore.kernel.org/all/20240126041126.1927228-23-michael.roth@amd.com/.

It was one thing when there were four of CPU feature masks, but with
over 20 it is going to cause mistakes, e.g.,
https://lore.kernel.org/lkml/aaed79d5-d683-d1bc-7ba1-b33c8d6db618@suse.com/.

We want to eliminate the stupidly repeated exercise to manually assign
features to CPU feature words through introducing an AWK script to
automatically generate a header with required and disabled CPU feature
masks based on current build config, and this patch set does that.


H. Peter Anvin (Intel) (2):
  x86/cpufeatures: Add {required,disabled} feature configs
  x86/cpufeatures: Generate a feature mask header based on build config

Xin Li (Intel) (1):
  x86/cpufeatures: Remove {disabled,required}-features.h

 arch/x86/Kconfig                              |   4 +-
 arch/x86/Kconfig.cpu                          |  16 +-
 arch/x86/Kconfig.cpufeatures                  | 153 +++++++++++++++++
 arch/x86/Makefile                             |  17 +-
 arch/x86/boot/cpucheck.c                      |   3 +-
 arch/x86/boot/cpuflags.c                      |   1 -
 arch/x86/boot/mkcpustr.c                      |   3 +-
 arch/x86/include/asm/Kbuild                   |   1 +
 arch/x86/include/asm/asm-prototypes.h         |   2 +-
 arch/x86/include/asm/atomic64_32.h            |   2 +-
 arch/x86/include/asm/bitops.h                 |   4 +-
 arch/x86/include/asm/cmpxchg_32.h             |   2 +-
 arch/x86/include/asm/cpufeature.h             |   1 +
 arch/x86/include/asm/cpufeatures.h            |   8 -
 arch/x86/include/asm/disabled-features.h      | 161 ------------------
 arch/x86/include/asm/required-features.h      | 105 ------------
 arch/x86/kernel/verify_cpu.S                  |   1 +
 arch/x86/lib/Makefile                         |   2 +-
 arch/x86/lib/cmpxchg8b_emu.S                  |   2 +-
 arch/x86/tools/featuremasks.awk               | 108 ++++++++++++
 lib/atomic64_test.c                           |   2 +-
 tools/arch/x86/include/asm/cpufeatures.h      |   8 -
 .../arch/x86/include/asm/disabled-features.h  | 161 ------------------
 .../arch/x86/include/asm/required-features.h  | 105 ------------
 tools/perf/check-headers.sh                   |   2 -
 25 files changed, 306 insertions(+), 568 deletions(-)
 create mode 100644 arch/x86/Kconfig.cpufeatures
 delete mode 100644 arch/x86/include/asm/disabled-features.h
 delete mode 100644 arch/x86/include/asm/required-features.h
 create mode 100755 arch/x86/tools/featuremasks.awk
 delete mode 100644 tools/arch/x86/include/asm/disabled-features.h
 delete mode 100644 tools/arch/x86/include/asm/required-features.h


base-commit: c064e5cb8336a5ee3471cc6a376cc19e19aa85de
-- 
2.45.0


^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2024-06-22 17:35 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-05-09 20:53 [RESEND v1 0/3] x86/cpufeatures: Automatically generate required and disabled feature masks Xin Li (Intel)
2024-05-09 20:53 ` [RESEND v1 1/3] x86/cpufeatures: Add {required,disabled} feature configs Xin Li (Intel)
2024-06-12 13:33   ` Borislav Petkov
2024-06-13  2:56     ` Xin Li
2024-05-09 20:53 ` [RESEND v1 2/3] x86/cpufeatures: Generate a feature mask header based on build config Xin Li (Intel)
2024-06-16  7:26   ` Xin Li
2024-06-17 13:46     ` H. Peter Anvin
2024-06-22 17:34       ` Xin Li
2024-05-09 20:53 ` [RESEND v1 3/3] x86/cpufeatures: Remove {disabled,required}-features.h Xin Li (Intel)

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox

all inboxes | Powered by JetHome®