Messages in this thread | | | Subject | Re: [PATCH] x86/bus_lock: Don't assume the init value of DEBUGCTLMSR.BUS_LOCK_DETECT to be zero | From | Chenyi Qiang <> | Date | Fri, 17 Sep 2021 10:52:02 +0800 |
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Kindly ping for this minor change.
Thanks Chenyi
On 9/1/2021 4:40 PM, Chenyi Qiang wrote: > It's possible that BIOS/firmware has set DEBUGCTLMSR_BUS_LOCK_DETECT, or > this kernel has been kexec'd from a kernel that enabled bus lock > detection. > > Disable bus lock detection explicitly if not wanted. > > Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com> > Reviewed-by: Tony Luck <tony.luck@intel.com> > --- > arch/x86/kernel/cpu/intel.c | 27 ++++++++++++++------------- > 1 file changed, 14 insertions(+), 13 deletions(-) > > diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c > index 8321c43554a1..38dda04d9342 100644 > --- a/arch/x86/kernel/cpu/intel.c > +++ b/arch/x86/kernel/cpu/intel.c > @@ -1152,22 +1152,23 @@ static void bus_lock_init(void) > { > u64 val; > > - /* > - * Warn and fatal are handled by #AC for split lock if #AC for > - * split lock is supported. > - */ > - if (!boot_cpu_has(X86_FEATURE_BUS_LOCK_DETECT) || > - (boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT) && > - (sld_state == sld_warn || sld_state == sld_fatal)) || > - sld_state == sld_off) > + if (!boot_cpu_has(X86_FEATURE_BUS_LOCK_DETECT)) > return; > > - /* > - * Enable #DB for bus lock. All bus locks are handled in #DB except > - * split locks are handled in #AC in the fatal case. > - */ > rdmsrl(MSR_IA32_DEBUGCTLMSR, val); > - val |= DEBUGCTLMSR_BUS_LOCK_DETECT; > + > + if ((boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT) && > + (sld_state == sld_warn || sld_state == sld_fatal)) || > + sld_state == sld_off) { > + /* > + * Warn and fatal are handled by #AC for split lock if #AC for > + * split lock is supported. > + */ > + val &= ~DEBUGCTLMSR_BUS_LOCK_DETECT; > + } else { > + val |= DEBUGCTLMSR_BUS_LOCK_DETECT; > + } > + > wrmsrl(MSR_IA32_DEBUGCTLMSR, val); > } > >
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