linux-kernel - Re: [PATCH v6 6/6] drivers/node: Show in sysfs node's crypto capabilities

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Message-ID: <5ee34cad-8daf-6282-f2ed-cbc92a89d013@amd.com>
Date:   Fri, 4 Feb 2022 11:12:04 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Borislav Petkov <bp@...en8.de>,
        "Limonciello, Mario" <mario.limonciello@....com>
Cc:     Martin Fernandez <martin.fernandez@...ypsium.com>,
        linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, linux-mm@...ck.org,
        tglx@...utronix.de, mingo@...hat.com, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, ardb@...nel.org,
        dvhart@...radead.org, andy@...radead.org,
        gregkh@...uxfoundation.org, rafael@...nel.org, rppt@...nel.org,
        akpm@...ux-foundation.org, daniel.gutson@...ypsium.com,
        hughsient@...il.com, alex.bazhaniuk@...ypsium.com,
        alison.schofield@...el.com, keescook@...omium.org
Subject: Re: [PATCH v6 6/6] drivers/node: Show in sysfs node's crypto
 capabilities

On 2/4/22 10:28, Borislav Petkov wrote:
> On Fri, Feb 04, 2022 at 10:23:22AM -0600, Limonciello, Mario wrote:
>>>>> As there is interest in seeing these capabilities from userspace, it
> 
> This needs to be explained in a lot more detail: why, what is going to
> use it, how, etc.
> 
> We don't do user-visible APIs just because.
> 
>> As Tom agreed in previous post, Boris is mistaken here.  I just double
>> checked on my side on a workstation that supports SME and comparing
>> /proc/cpuinfo before and after SME is enabled via mem_encrypt=on.  I
>> confirmed that nothing changed.
> 
> Then we should clear that "sme" flag if memory encryption is not
> enabled. Like we do for all other flags.

If we do that, then this will have to be re-worked:

https://elixir.bootlin.com/linux/latest/source/arch/x86/kernel/process.c#L761

Thanks,
Tom

>