x86/bus_lock: Don't assume the init value of DEBUGCTLMSR.BUS_LOCK_DETECT to be zero

mainline inclusion
from mainline-v6.0-rc1
commit ffa6482e
category: feature
feature: KVM Bus Lock Debug Exception
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I5RHW7
CVE: N/A
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/


commit/?id=ffa6482e

Intel-SIG: commit ffa6482e ("x86/bus_lock: Don't assume the init value of DEBUGCTLMSR.BUS_LOCK_DETECT to be zero")

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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: ebb1064e ("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


Signed-off-by: Aichun Shi <aichun.shi@intel.com>