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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Laurent Dufour <ldufour@linux.ibm.com>, benh@kernel.crashing.org,
        paulus@samba.org, linuxppc-dev@lists.ozlabs.org
Cc:     nathanl@linux.ibm.com, cheloha@linux.ibm.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc/pseries: export LPAR security flavor in lparcfg
In-Reply-To: <2c67c119-c1ec-b079-da54-0bf2f316c734@linux.ibm.com>
References: <20210304114240.54112-1-ldufour@linux.ibm.com>
 <871rcuruee.fsf@mpe.ellerman.id.au>
 <2c67c119-c1ec-b079-da54-0bf2f316c734@linux.ibm.com>
Date:   Fri, 05 Mar 2021 22:43:55 +1100
Message-ID: <87wnulrfk4.fsf@mpe.ellerman.id.au>
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Laurent Dufour <ldufour@linux.ibm.com> writes:
> Le 05/03/2021 =C3=A0 07:23, Michael Ellerman a =C3=A9crit=C2=A0:
>> Laurent Dufour <ldufour@linux.ibm.com> writes:
>>> This is helpful to read the security flavor from inside the LPAR.
>>=20
>> We already have /sys/kernel/debug/powerpc/security_features.
>>=20
>> Is that not sufficient?
>
> Not really, it only reports that security mitigation are on or off but no=
t the=20
> level set through the ASMI menu. Furthermore, reporting it through
> /proc/powerpc/lparcfg allows an easy processing by the lparstat command (=
see below).
>
>>=20
>>> Export it like this in /proc/powerpc/lparcfg:
>>>
>>> $ grep security_flavor /proc/powerpc/lparcfg
>>> security_flavor=3D1
>>>
>>> Value means:
>>> 0 Speculative execution fully enabled
>>> 1 Speculative execution controls to mitigate user-to-kernel attacks
>>> 2 Speculative execution controls to mitigate user-to-kernel and
>>>    user-to-user side-channel attacks
>>=20
>> Those strings come from the FSP help, but we have no guarantee it won't
>> mean something different in future.
>
> I think this is nailed down, those strings came from:
> https://www.ibm.com/support/pages/node/715841
>
> Where it is written (regarding AIX):
>
> On an LPAR, one can use lparstat -x to display the current mitigation mod=
e:
> 0 =3D Speculative execution fully enabled
> 1 =3D Speculative execution controls to mitigate user-to-kernel side-chan=
nel attacks
> 2 =3D Speculative execution controls to mitigate user-to-kernel and user-=
to-user=20
> side-channel attacks
>
> We have been requested to provide almost the same, which I proposed in=20
> powerpc-utils:
> https://groups.google.com/g/powerpc-utils-devel/c/NaKXvdyl_UI/m/wa2stpIDA=
QAJ

OK. Do you mind sending a v2 with all those details incorporated into
the change log?

cheers