linux-kernel - Re: [PATCH 2/7] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions

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Message-ID: <87y2qisdza.fsf@nanos.tec.linutronix.de>
Date:   Sun, 26 Apr 2020 13:06:33 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Fenghua Yu <fenghua.yu@...el.com>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>, H Peter Anvin <hpa@...or.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Jacob Jun Pan <jacob.jun.pan@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Sohil Mehta <sohil.mehta@...el.com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>,
        iommu@...ts.linux-foundation.org, Fenghua Yu <fenghua.yu@...el.com>
Subject: Re: [PATCH 2/7] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions

Fenghua Yu <fenghua.yu@...el.com> writes:
> A user space application can execute ENQCMD instruction to submit work
> to device. The kernel executes ENQCMDS instruction to submit work to
> device.

So a user space application _can_ execute ENQCMD and the kernel
executes ENQCMDS. And both submit work to device.

> There is a lot of other enabling needed for the instructions to actually
> be usable in user space and the kernel, and that enabling is coming later
> in the series and in device drivers.

That's important information to the enumeration of the instructions in
which way?

Thanks,

        tglx