linux-kernel - Re: [PATCH v2 2/2] x86/sgx: Add SGX

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Message-ID: <9ec30322d0d133bfa695da475d4de736994a6c68.camel@kernel.org>
Date:   Thu, 19 Aug 2021 15:52:48 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     linux-sgx@...r.kernel.org
Cc:     Shuah Khan <shuah@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Jonathan Corbet <corbet@....net>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...nel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Krish Sadhukhan <krish.sadhukhan@...cle.com>,
        Saravanan D <saravanand@...com>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 2/2] x86/sgx: Add SGX_MemTotal to /proc/meminfo

On Thu, 2021-08-19 at 15:48 +0300, Jarkko Sakkinen wrote:
> The amount of SGX memory on the system is determined by the BIOS and it
> varies wildly between systems.  It can be from dozens of MB's on desktops
> or VM's, up to many GB's on servers.  Just like for regular memory, it is
> sometimes useful to know the amount of usable SGX memory in the system.
> 
> Add SGX_MemTotal field to /proc/meminfo, which shows the total amount of
> usable SGX memory in the system.  E.g. with 32 MB reserved for SGX from
> BIOS, the printout would be:
> 
> SGX_MemTotal:      22528 kB
> 
> It is less than 32 MB because some of the space is reserved for Enclave
> Page Cache Metadata (EPCM), which contains state variables for all the
> pages in the Enclave Page Cache (EPC).  The latter contains the pages,
> which applications can use to create enclaves.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>

While working on this, I noticed that suddenly my i5-9660k desktop fully
supports SGX on Linux. I don't recall that it has worked in the patch.
Maybe this is because of some firmware/ucode update, do not really know,
but definitely not a bad thing.

Perhaps this casts through other 9th gen Core CPU's.

The motherboard I have in this machine is AORUS Elite z390.

/Jarkko