Hi folks,
This series fixes __ro_after_init keys used in modules (courtesy of PeterZ) and
flags more keys as __ro_after_init.
Compile & boot tested for x86_64_defconfig and i386_defconfig.
@Peter, regarding making __use_tsc x86_32-only, I hit a few snags:
Currently, for the static key to be enabled, we (mostly) need:
o X86_FEATURE_TSC is in CPUID
o determine_cpu_tsc_frequencies passes
All X86_64 systems have a TSC, so the CPUID feature is a given there.
Calibrating the TSC can end up depending on different things:
o CPUID accepting 0x16 as eax input (cf. cpu_khz_from_cpuid())
o MSR_FSB_FREQ being available (cf. cpu_khz_from_msr())
o pit_hpet_ptimer_calibrate_cpu() doesn't mess up
I couldn't find any guarantees for X86_64 on having the processor frequency
information CPUID leaf, nor for the FSB_FREQ MSR (both tsc_msr_cpu_ids and
the SDM seem to point at only a handful of models).
pit_hpet_ptimer_calibrate_cpu() relies on having either HPET or the ACPI PM
timer, the latter being widely available, though X86_PM_TIMER can be
disabled via EXPERT.
The question here is: are there any guarantees that at least one of these
can be relied upon for x86_64?
And with all of that, there is still the "apicpmtimer" cmdline option which
currently invokes notsc_setup() on x86_64. The justification I found for it was
in 0c3749c41f5e ("[PATCH] x86_64: Calibrate APIC timer using PM timer"):
"""
On some broken motherboards (at least one NForce3 based AMD64 laptop)
the PIT timer runs at a incorrect frequency. This patch adds a new
option "apicpmtimer" that allows to use the APIC timer and calibrate it
using the PMTimer.
"""
Revisions
=========
v2 -> v3
++++++++
o Rebased against latest upstream
o Fixed up jump_label_del_module() error in first patch reported by kernel test
robot
http://lore.kernel.org/r/202402191313.3276317d-oliver.sang@xxxxxxxxx
o Removed mds_user_clear patch; key was switched to an ALTERNATIVE by
6613d82e617d ("x86/bugs: Use ALTERNATIVE() instead of mds_user_clear static key")
v1 -> v2
++++++++
o Collected tags (Josh, Sean)
o Fixed CONFIG_JUMP_LABEL=n compile fail (lkp)
Cheers,
Valentin
Peter Zijlstra (1):
jump_label,module: Don't alloc static_key_mod for __ro_after_init keys
Valentin Schneider (3):
context_tracking: Make context_tracking_key __ro_after_init
x86/kvm: Make kvm_async_pf_enabled __ro_after_init
x86/tsc: Make __use_tsc __ro_after_init
arch/x86/kernel/kvm.c | 2 +-
arch/x86/kernel/tsc.c | 2 +-
include/asm-generic/sections.h | 5 ++++
include/linux/jump_label.h | 3 ++
init/main.c | 1 +
kernel/context_tracking.c | 2 +-
kernel/jump_label.c | 53 ++++++++++++++++++++++++++++++++++
7 files changed, 65 insertions(+), 3 deletions(-)
--
2.43.0
