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Subject[PATCH 4.14 51/53] x86/microcode, cpuhotplug: Add a microcode loader CPU hotplug callback
Date
From: Borislav Petkov <bp@suse.de>

commit 78f4e932f7760d965fb1569025d1576ab77557c5 upstream.

Adric Blake reported the following warning during suspend-resume:

Enabling non-boot CPUs ...
x86: Booting SMP configuration:
smpboot: Booting Node 0 Processor 1 APIC 0x2
unchecked MSR access error: WRMSR to 0x10f (tried to write 0x0000000000000000) \
at rIP: 0xffffffff8d267924 (native_write_msr+0x4/0x20)
Call Trace:
intel_set_tfa
intel_pmu_cpu_starting
? x86_pmu_dead_cpu
x86_pmu_starting_cpu
cpuhp_invoke_callback
? _raw_spin_lock_irqsave
notify_cpu_starting
start_secondary
secondary_startup_64
microcode: sig=0x806ea, pf=0x80, revision=0x96
microcode: updated to revision 0xb4, date = 2019-04-01
CPU1 is up

The MSR in question is MSR_TFA_RTM_FORCE_ABORT and that MSR is emulated
by microcode. The log above shows that the microcode loader callback
happens after the PMU restoration, leading to the conjecture that
because the microcode hasn't been updated yet, that MSR is not present
yet, leading to the #GP.

Add a microcode loader-specific hotplug vector which comes before
the PERF vectors and thus executes earlier and makes sure the MSR is
present.

Fixes: 400816f60c54 ("perf/x86/intel: Implement support for TSX Force Abort")
Reported-by: Adric Blake <promarbler14@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: x86@kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=203637
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/cpu/microcode/core.c | 2 +-
include/linux/cpuhotplug.h | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -873,7 +873,7 @@ int __init microcode_init(void)
goto out_ucode_group;

register_syscore_ops(&mc_syscore_ops);
- cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/microcode:online",
+ cpuhp_setup_state_nocalls(CPUHP_AP_MICROCODE_LOADER, "x86/microcode:online",
mc_cpu_online, mc_cpu_down_prep);

pr_info("Microcode Update Driver: v%s.", DRIVER_VERSION);
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -100,6 +100,7 @@ enum cpuhp_state {
CPUHP_AP_IRQ_ARMADA_XP_STARTING,
CPUHP_AP_IRQ_BCM2836_STARTING,
CPUHP_AP_ARM_MVEBU_COHERENCY,
+ CPUHP_AP_MICROCODE_LOADER,
CPUHP_AP_PERF_X86_AMD_UNCORE_STARTING,
CPUHP_AP_PERF_X86_STARTING,
CPUHP_AP_PERF_X86_AMD_IBS_STARTING,

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