linux-kernel - Re: [PATCH v2 0/2] x86/traps: Fix DR6/DR7 initialization

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <80636908-b355-455b-bac8-4703210ab65d@intel.com>
Date: Tue, 17 Jun 2025 10:55:18 -0700
From: Sohil Mehta <sohil.mehta@...el.com>
To: "Xin Li (Intel)" <xin@...or.com>, <linux-kernel@...r.kernel.org>,
	<kvm@...r.kernel.org>
CC: <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>, <x86@...nel.org>, <hpa@...or.com>,
	<seanjc@...gle.com>, <pbonzini@...hat.com>, <peterz@...radead.org>,
	<brgerst@...il.com>, <tony.luck@...el.com>, <fenghuay@...dia.com>
Subject: Re: [PATCH v2 0/2] x86/traps: Fix DR6/DR7 initialization

On 6/17/2025 12:32 AM, Xin Li (Intel) wrote:
> Sohil reported seeing a split lock warning when running a test that
> generates userspace #DB:
> 
>   x86/split lock detection: #DB: sigtrap_loop_64/4614 took a bus_lock trap at address: 0x4011ae
> 

The following patches fix the issue for me.

Tested-by: Sohil Mehta <sohil.mehta@...el.com>

> 
> Xin Li (Intel) (2):
>   x86/traps: Initialize DR6 by writing its architectural reset value
>   x86/traps: Initialize DR7 by writing its architectural reset value
> 
>  arch/x86/include/asm/debugreg.h      | 14 ++++++++----
>  arch/x86/include/asm/kvm_host.h      |  2 +-
>  arch/x86/include/uapi/asm/debugreg.h |  7 +++++-
>  arch/x86/kernel/cpu/common.c         | 17 ++++++--------
>  arch/x86/kernel/kgdb.c               |  2 +-
>  arch/x86/kernel/process_32.c         |  2 +-
>  arch/x86/kernel/process_64.c         |  2 +-
>  arch/x86/kernel/traps.c              | 34 +++++++++++++++++-----------
>  arch/x86/kvm/x86.c                   |  4 ++--
>  9 files changed, 50 insertions(+), 34 deletions(-)
> 
> 
> base-commit: 594902c986e269660302f09df9ec4bf1cf017b77