linux-kernel - Re: [PATCH v3 2/4] x86/bus

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Message-ID: <240900d1-b9ff-7bcb-9cd6-13a511492874@amd.com>
Date: Tue, 6 Aug 2024 09:08:35 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: Ravi Bangoria <ravi.bangoria@....com>, tglx@...utronix.de,
 mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
 seanjc@...gle.com, pbonzini@...hat.com, jmattson@...gle.com
Cc: 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,
 manali.shukla@....com
Subject: Re: [PATCH v3 2/4] x86/bus_lock: Add support for AMD

On 8/6/24 07:54, Ravi Bangoria wrote:
> 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].
> 
> [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
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@....com>

Reviewed-by: Tom Lendacky <thomas.lendacky@....com>

> ---
>  arch/x86/include/asm/cpu.h     | 8 +++++---
>  arch/x86/kernel/cpu/bus_lock.c | 4 ++--
>  arch/x86/kernel/cpu/common.c   | 2 ++
>  arch/x86/kernel/cpu/intel.c    | 1 -
>  include/linux/sched.h          | 2 +-
>  5 files changed, 10 insertions(+), 7 deletions(-)
>