Refactor identify_cpu() machinery on x86 and then implement a fix for
a bug when cpu capabilities are temporarily cleared within an
interruptable window. For more details and discussion see the relevant
bug report [1] and patch #5 ("x86/cpu: Don't transiently clear the
boot CPU's capabilities").

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>

[1] https://lore.kernel.org/bpf/20260610175651.647515-1-ihor.solodrai@linux.dev/

---

v2->v3:
  * Commit message edits on patches #1, #2, #5

v2: https://lore.kernel.org/bpf/20260814235134.3461435-1-ihor.solodrai@linux.dev/

v1->v2:
  * Rewrite commit messages to fit more conventional structure (Boris)
  * Drop identify_cpu_32() helper, it's unnecessary (Boris)
  * New patch (#2): now early_identify_cpu() resets boot_cpu_data
    through init_cpu_info() as well
  * The boot CPU reset is now skipped on 32-bit too (sashiko)

v1: https://lore.kernel.org/bpf/20260704002046.3859585-1-ihor.solodrai@linux.dev/

---

Ihor Solodrai (5):
  x86/cpu: Factor init_cpu_info() out of identify_cpu()
  x86/cpu: Initialize boot CPU cpuinfo defaults early
  x86/cpu: Inline generic_identify() into identify_cpu()
  x86/cpu: Move 32-bit SEP setup into identify_cpu()
  x86/cpu: Don't transiently clear the boot CPU's capabilities

 arch/x86/kernel/cpu/common.c | 92 +++++++++++++++++-------------------
 1 file changed, 44 insertions(+), 48 deletions(-)


base-commit: fd73f4a6659897191fa0d40695fe370925dd3780
-- 
2.55.0