From: Thomas Gleixner <tglx@linutronix.de>
To: Fenghua Yu <fenghua.yu@intel.com>, Borislav Petkov <bp@alien8.de>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Tony Luck <tony.luck@intel.com>,
Randy Dunlap <rdunlap@infradead.org>,
Xiaoyao Li <xiaoyao.li@intel.com>,
Ravi V Shankar <ravi.v.shankar@intel.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
Fenghua Yu <fenghua.yu@intel.com>
Subject: Re: [PATCH v4 1/4] x86/cpufeatures: Enumerate #DB for bus lock detection
Date: Wed, 27 Jan 2021 22:13:13 +0100 [thread overview]
Message-ID: <87wnvydqxi.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201124205245.4164633-2-fenghua.yu@intel.com>
On Tue, Nov 24 2020 at 20:52, Fenghua Yu wrote:
> A bus lock is acquired though either split locked access to
> writeback (WB) memory or any locked access to non-WB memory. This is
> typically >1000 cycles slower than an atomic operation within a cache
> line. It also disrupts performance on other cores.
>
> Some CPUs have ability to notify the kernel by an #DB trap after a user
> instruction acquires a bus lock and is executed. This allows the kernel
> to enforce user application throttling or mitigations.
That's nice, but how does that interact with a data breakpoint on the
same location?
Also the information you pointed to in the cover letter
> [1] Intel Instruction Set Extension Chapter 8:
> https://software.intel.com/sites/default/files/managed/c5/15/architecture-instruction-set-extensions-programming-reference.pdf
does not contain anything which is even remotely related to this patch
series. That chapter describes another bit in TEST_CTRL_MSR ...
Thanks,
tglx
next prev parent reply other threads:[~2021-01-27 21:14 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-24 20:52 [PATCH v4 0/4] x86/bus_lock: Enable bus lock detection Fenghua Yu
2020-11-24 20:52 ` [PATCH v4 1/4] x86/cpufeatures: Enumerate #DB for " Fenghua Yu
2021-01-27 21:13 ` Thomas Gleixner [this message]
2021-01-27 22:39 ` Yu, Fenghua
2021-01-27 23:23 ` Thomas Gleixner
2020-11-24 20:52 ` [PATCH v4 2/4] x86/bus_lock: Handle warn and fatal in #DB for bus lock Fenghua Yu
2021-01-27 21:16 ` Thomas Gleixner
2020-11-24 20:52 ` [PATCH v4 3/4] x86/bus_lock: Set rate limit " Fenghua Yu
2021-01-27 21:57 ` Thomas Gleixner
2020-11-24 20:52 ` [PATCH v4 4/4] Documentation/admin-guide: Change doc for split_lock_detect parameter Fenghua Yu
2021-01-27 22:09 ` Thomas Gleixner
2020-12-02 20:36 ` [PATCH v4 0/4] x86/bus_lock: Enable bus lock detection Yu, Fenghua
2021-01-04 19:42 ` Fenghua Yu
2021-01-25 19:27 ` Fenghua Yu
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