Re: [PATCH 2/3] x86/bus_lock: Add support for AMD

Jim Mattson
2024-05-06T16:24:21Z

On Sun, Apr 28, 2024 at 11:08 PM Ravi Bangoria <ravi.bangoria@amd.com> wrote:
>
> 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].
>
> [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

Is there any chance of getting something similar to Intel's "VMM
bus-lock detection," which causes a trap-style VM-exit on a bus lock
event?