[v3,0/4] x86/cpu: Add Bus Lock Detect support for AMD

Message

Ravi Bangoria Aug. 6, 2024, 12:54 p.m. UTC

Add Bus Lock Detect (called Bus Lock Trap in AMD docs) support for AMD
platforms. Bus Lock Detect is enumerated with CPUID Fn0000_0007_ECX_x0
bit [24 / BUSLOCKTRAP]. It can be enabled through MSR_IA32_DEBUGCTLMSR.
When enabled, hardware clears DR6[11] and raises a #DB exception on
occurrence of Bus Lock if CPL > 0. More detail about the feature can be
found in AMD APM[1].

Patches are prepared on tip/master (435dfff07e5b).

[1]: AMD64 Architecture Programmer's Manual Pub. 40332, Rev. 4.07 - June
     2023, Vol 2, 13.1.3.6 Bus Lock Trap
     https://bugzilla.kernel.org/attachment.cgi?id=304653

v2: https://lore.kernel.org/r/[e-mail]
v2->v3:
 - Fix build failure reported by LKP test bot
 - Reword commit messages

Note:
A Qemu fix is also require to handle a corner case where a hardware
instruction or data breakpoint is created by Qemu remote debugger (gdb)
on the same instruction which also causes a Bus Lock. Qemu patch to
handle it can be found at:
https://lore.kernel.org/r/[e-mail]

Ravi Bangoria (4):
  x86/split_lock: Move Split and Bus lock code to a dedicated file
  x86/bus_lock: Add support for AMD
  KVM: SVM: Don't advertise Bus Lock Detect to guest if SVM support is
    missing
  KVM: SVM: Add Bus Lock Detect support

 arch/x86/include/asm/cpu.h     |  12 +-
 arch/x86/kernel/cpu/Makefile   |   1 +
 arch/x86/kernel/cpu/bus_lock.c | 410 +++++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/common.c   |   2 +
 arch/x86/kernel/cpu/intel.c    | 407 --------------------------------
 arch/x86/kvm/svm/nested.c      |   3 +-
 arch/x86/kvm/svm/svm.c         |  16 +-
 include/linux/sched.h          |   2 +-
 8 files changed, 440 insertions(+), 413 deletions(-)
 create mode 100644 arch/x86/kernel/cpu/bus_lock.c