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x86/aperfmperf: Fix deadlock on cpu_hotplug_lock

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The broken patch results in a call to init_freq_invariance_cppc() in a CPU
hotplug handler in both the path for initially present CPUs and those
hotplugged later.  That function includes a one time call to
amd_set_max_freq_ratio() which in turn calls freq_invariance_enable() that has
a static_branch_enable() which takes the cpu_hotlug_lock which is already
held.

Avoid the deadlock by using static_branch_enable_cpuslocked() as the lock will
always be already held.  The equivalent path on Intel does not already hold
this lock, so take it around the call to freq_invariance_enable(), which
results in it being held over the call to register_syscall_ops, which looks to
be safe to do.

Fixes: c1385c1f0b ("ACPI: processor: Simplify initial onlining to use same path for cold and hotplug")
Closes: https://lore.kernel.org/all/CABXGCsPvqBfL5hQDOARwfqasLRJ_eNPBbCngZ257HOe=xbWDkA@mail.gmail.com/
Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240729105504.2170-1-Jonathan.Cameron@huawei.com
This commit is contained in:
Jonathan Cameron
2024-07-29 11:55:04 +01:00
committed by Borislav Petkov (AMD)
parent 8400291e28
commit 0f7ced7d62
1 changed files with 4 additions and 2 deletions
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6
arch/x86/kernel/cpu/aperfmperf.c
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@@ -306,7 +306,7 @@ static void freq_invariance_enable(void)
WARN_ON_ONCE(1);
return;
}
static_branch_enable(&arch_scale_freq_key);
static_branch_enable_cpuslocked(&arch_scale_freq_key);
register_freq_invariance_syscore_ops();
pr_info("Estimated ratio of average max frequency by base frequency (times 1024): %llu\n", arch_max_freq_ratio);
}
@@ -323,8 +323,10 @@ static void __init bp_init_freq_invariance(void)
if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
return;
if (intel_set_max_freq_ratio())
if (intel_set_max_freq_ratio()) {
guard(cpus_read_lock)();
freq_invariance_enable();
}
}
static void disable_freq_invariance_workfn(struct work_struct *work)