From: Valentin Schneider <vschneid@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
linux-arch@vger.kernel.org, x86@kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Arnd Bergmann <arnd@arndb.de>, Jason Baron <jbaron@akamai.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ard Biesheuvel <ardb@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Feng Tang <feng.tang@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Mike Rapoport (IBM)" <rppt@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>,
David Hildenbrand <david@redhat.com>,
"ndesaulniers@google.com" <ndesaulniers@google.com>,
Michael Kelley <mikelley@microsoft.com>,
"Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Subject: [PATCH v2 0/5] jump_label: Fix __ro_after_init keys for modules & annotate some keys
Date: Tue, 6 Feb 2024 18:39:06 +0100 [thread overview]
Message-ID: <20240206173911.4131670-1-vschneid@redhat.com> (raw)
Hi folks,
This series fixes __ro_after_init keys used in modules (courtesy of PeterZ) and
flags more keys as __ro_after_init. Further context for why I'm looking into
this here: http://lore.kernel.org/r/20230720163056.2564824-1-vschneid@redhat.com
Compile & boot tested for x86_64_defconfig and i386_defconfig.
@Peter, regarding making __use_tsc x86_32, 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
=========
v1 -> v2
++++++++
- Collected tags (Josh, Sean)
- 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 (4):
context_tracking: Make context_tracking_key __ro_after_init
x86/kvm: Make kvm_async_pf_enabled __ro_after_init
x86/speculation: Make mds_user_clear __ro_after_init
x86/tsc: Make __use_tsc __ro_after_init
arch/x86/kernel/cpu/bugs.c | 2 +-
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 | 49 ++++++++++++++++++++++++++++++++++
8 files changed, 62 insertions(+), 4 deletions(-)
--
2.43.0
next reply other threads:[~2024-02-06 17:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-06 17:39 Valentin Schneider [this message]
2024-02-06 17:39 ` [PATCH v2 1/5] jump_label,module: Don't alloc static_key_mod for __ro_after_init keys Valentin Schneider
2024-02-06 17:39 ` [PATCH v2 2/5] context_tracking: Make context_tracking_key __ro_after_init Valentin Schneider
2024-02-19 6:10 ` kernel test robot
2024-02-06 17:39 ` [PATCH v2 3/5] x86/kvm: Make kvm_async_pf_enabled __ro_after_init Valentin Schneider
2024-02-06 17:39 ` [PATCH v2 4/5] x86/speculation: Make mds_user_clear __ro_after_init Valentin Schneider
2024-02-06 17:39 ` [PATCH v2 5/5] x86/tsc: Make __use_tsc __ro_after_init Valentin Schneider
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