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Subject: Re: [PATCH v2 0/2] MTE support for KVM guest
To:     Steven Price <steven.price@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
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        linux-kernel@vger.kernel.org, Dave Martin <Dave.Martin@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>, qemu-devel@nongnu.org,
        Juan Quintela <quintela@redhat.com>,
        "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
        Peter Maydell <Peter.Maydell@arm.com>,
        Haibo Xu <Haibo.Xu@arm.com>
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From:   Richard Henderson <richard.henderson@linaro.org>
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Date:   Thu, 10 Sep 2020 08:36:44 -0700
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On 9/10/20 3:24 AM, Steven Price wrote:
> It is a shame, however I suspect this is because to use those instructions you
> need to know the block size held in GMID_EL1. And at least in theory that could
> vary between CPUs.

Which is no different from having to read DCZID_EL0 in order to implement
memset, in my opinion.  But, whatever.


> When we have some real hardware it would be worth profiling this. At the moment
> I've no idea whether the kernel entry overhead would make such an interface
> useful from a performance perspective or not.

Yep.


r~