From: Chenyi Qiang <chenyi.qiang@intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Tony Luck <tony.luck@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Xiaoyao Li <xiaoyao.li@intel.com>,
linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH] x86/bus_lock: Don't assume the init value of DEBUGCTLMSR.BUS_LOCK_DETECT to be zero
Date: Mon, 25 Oct 2021 14:14:28 +0800 [thread overview]
Message-ID: <4a757c43-dfc8-6da4-944e-9bf687d7e3bc@intel.com> (raw)
In-Reply-To: <YW766qk0W6K5rhrU@google.com>
On 10/20/2021 1:05 AM, Sean Christopherson wrote:
> On Wed, Sep 01, 2021, Chenyi Qiang wrote:
>> It's possible that BIOS/firmware has set DEBUGCTLMSR_BUS_LOCK_DETECT, or
>> this kernel has been kexec'd from a kernel that enabled bus lock
>> detection.
>
> This feels like the kernel should explicitly zero out the entire MSR somewhere
> in the generic boot flow. E.g. something like this somewhere.
>
Yes. Meanwhile, I think kernel code prefers to explicitly set/clear the
control bit according to the parameter. Maybe both changes should be
applied.
> #ifndef CONFIG_X86_DEBUGCTLMSR
> if (boot_cpu_data.x86 < 6)
> return;
> #endifa
>
> wrmsrl(MSR_IA32_DEBUGCTLMSR, 0);
>
prev parent reply other threads:[~2021-10-25 6:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-01 8:40 Chenyi Qiang
2021-09-17 2:52 ` Chenyi Qiang
2021-10-19 7:34 ` Chenyi Qiang
2021-10-19 17:05 ` Sean Christopherson
2021-10-25 6:14 ` Chenyi Qiang [this message]
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