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

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Message-ID: <CALMp9eQzbNVJpuxp1orNswnyfKy=aFSPYFRnd3H7fbi0+NfDvw@mail.gmail.com>
Date: Mon, 6 May 2024 09:24:00 -0700
From: Jim Mattson <jmattson@...gle.com>
To: Ravi Bangoria <ravi.bangoria@....com>
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, 
	dave.hansen@...ux.intel.com, seanjc@...gle.com, pbonzini@...hat.com, 
	thomas.lendacky@....com, hpa@...or.com, rmk+kernel@...linux.org.uk, 
	peterz@...radead.org, james.morse@....com, lukas.bulwahn@...il.com, 
	arjan@...ux.intel.com, j.granados@...sung.com, sibs@...natelecom.cn, 
	nik.borisov@...e.com, michael.roth@....com, nikunj.dadhania@....com, 
	babu.moger@....com, x86@...nel.org, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, santosh.shukla@....com, ananth.narayan@....com, 
	sandipan.das@....com
Subject: Re: [PATCH 2/3] x86/bus_lock: Add support for AMD

On Sun, Apr 28, 2024 at 11:08 PM Ravi Bangoria <ravi.bangoria@....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?