[PATCH 0/3] x86/cpu: Add Bus Lock Detect support for AMD

Ravi Bangoria
2024-04-29T06:07:10Z

Upcoming AMD uarch will support Bus Lock Detect (called Bus Lock Trap
in AMD docs). Add support for the same in Linux. Bus Lock Detect is
enumerated with cpuid 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/x86/cpu (e063b531d4e8)

Patch #3 depends on SEV-ES LBRV fix:
https://lore.kernel.org/r/20240416050338.517-1-ravi.bangoria@amd.com

[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

Ravi Bangoria (3):
x86/split_lock: Move Split and Bus lock code to a dedicated file
x86/bus_lock: Add support for AMD
KVM SVM: Add Bus Lock Detect support

arch/x86/include/asm/cpu.h | 4 +
arch/x86/kernel/cpu/Makefile | 1 +
arch/x86/kernel/cpu/amd.c | 2 +
arch/x86/kernel/cpu/intel.c | 407 ---------------------------
arch/x86/kernel/cpu/split-bus-lock.c | 406 ++++++++++++++++++++++++++
arch/x86/kvm/svm/nested.c | 3 +-
arch/x86/kvm/svm/svm.c | 16 +-
7 files changed, 430 insertions(+), 409 deletions(-)
create mode 100644 arch/x86/kernel/cpu/split-bus-lock.c

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2.44.0