diff options
| author | Chenyi Qiang | 2022-08-02 11:32:06 +0800 |
|---|---|---|
| committer | Ingo Molnar | 2022-08-02 13:42:00 +0200 |
| commit | ffa6482e461ff550325356ae705b79e256702ea9 (patch) | |
| tree | e191f4506dd6a5a482ad5962a031622346601ae8 /arch/x86 | |
| parent | 9de1f9c8ca5100a02a2e271bdbde36202e251b4b (diff) | |
x86/bus_lock: Don't assume the init value of DEBUGCTLMSR.BUS_LOCK_DETECT to be zero
It's possible that this kernel has been kexec'd from a kernel that
enabled bus lock detection, or (hypothetically) BIOS/firmware has set
DEBUGCTLMSR_BUS_LOCK_DETECT.
Disable bus lock detection explicitly if not wanted.
Fixes: ebb1064e7c2e ("x86/traps: Handle #DB for bus lock")
Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20220802033206.21333-1-chenyi.qiang@intel.com
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 663f6e6dd288..2d7ea5480ec3 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -1216,22 +1216,23 @@ 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); } |