linux-kernel - Re: [PATCH RFC v3] x86/sgx: Add /proc/sys/kernel/sgx/total

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Date:   Thu, 12 Aug 2021 22:53:01 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     linux-sgx@...r.kernel.org,
        Reinette Chatre <reinette.chatre@...el.com>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, Jonathan Corbet <corbet@....net>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH RFC v3] x86/sgx: Add /proc/sys/kernel/sgx/total_mem

On Wed, Aug 11, 2021 at 07:30:13AM -0700, Dave Hansen wrote:
> On 8/10/21 8:21 PM, Jarkko Sakkinen wrote:
> > +The following sysctl files can be found in the ``/proc/sys/kernel/sgx/`` directory:
> > +
> > +``total_mem``
> > +	The total amount of SGX protected memory in bytes available in the system
> > +	available for use. In other words, it describes the size of the Enclave
> > +	Page Cache (EPC).
> 
> I've been acting as if /proc is deprecated for new stuff.  Shouldn't
> this be going in sysfs?

Are sysctl variables deprecated too?

> I figured, at some point, someone is going to ask for NUMA statistics.
> That would tend to point in the direction of us needing something in:
> 
> 	/sys/devices/system/node/nodeN/
> 
> Maybe 'sgxinfo' or 'sgxstat' to go along with 'meminfo'.

Is conetents of meminfo freezed or can a new line added, e.g.

Node 0 SgxMemTotal:    32825700 kB

If a new file is needed, I would name it as "sgxmeminfo"

> But, we'll probably also end up needing some stats for other things.
> Folks have, for instance, asked for a counter of the number of
> instantiated enclaves.
> 
> We could also use the drivers' namespaces:
> 
> 	/sys/class/misc/sgx_enclave
> 	/sys/class/misc/sgx_provision
> 	/sys/class/misc/sgx_vepc
> 
> although that is a bit awkward for reporting global resources like memory.

I think these stats should be available when the driver is not enabled.

It would be best to find a global solution for the long-run.

/Jarkko