From: "Michal Suchánek" <msuchanek@suse.de>
To: Michael Ellerman <patch-notifications@ellerman.id.au>
Cc: Gustavo Walbon <gwalbon@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org, mikey@neuling.org,
maurosr@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
npiggin@gmail.com, diana.craciun@nxp.com, paulus@samba.org,
leitao@debian.org, gwalbon@linux.vnet.ibm.com,
stable@vger.kernel.org
Subject: Re: [PATCH] Fix wrong message when RFI Flush is disable
Date: Thu, 14 Nov 2019 10:31:38 +0100 [thread overview]
Message-ID: <20191114093138.GF11661@kitsune.suse.cz> (raw)
In-Reply-To: <47DFxM5mVHz9sNT@ozlabs.org>
On Thu, Nov 14, 2019 at 08:07:35PM +1100, Michael Ellerman wrote:
> On Thu, 2019-05-02 at 21:09:07 UTC, Gustavo Walbon wrote:
> > From: "Gustavo L. F. Walbon" <gwalbon@linux.ibm.com>
> >
> > The issue was showing "Mitigation" message via sysfs whatever the state of
> > "RFI Flush", but it should show "Vulnerable" when it is disabled.
> >
> > If you have "L1D private" feature enabled and not "RFI Flush" you are
> > vulnerable to meltdown attacks.
> >
> > "RFI Flush" is the key feature to mitigate the meltdown whatever the
> > "L1D private" state.
> >
> > SEC_FTR_L1D_THREAD_PRIV is a feature for Power9 only.
> >
> > So the message should be as the truth table shows.
> > CPU | L1D private | RFI Flush | sysfs |
> > ----| ----------- | --------- | ------------------------------------- |
> > P9 | False | False | Vulnerable
> > P9 | False | True | Mitigation: RFI Flush
> > P9 | True | False | Vulnerable: L1D private per thread
> > P9 | True | True | Mitigation: RFI Flush, L1D private per
> > | | | thread
> > P8 | False | False | Vulnerable
> > P8 | False | True | Mitigation: RFI Flush
> >
> > Output before this fix:
> > # cat /sys/devices/system/cpu/vulnerabilities/meltdown
> > Mitigation: RFI Flush, L1D private per thread
> > # echo 0 > /sys/kernel/debug/powerpc/rfi_flush
> > # cat /sys/devices/system/cpu/vulnerabilities/meltdown
> > Mitigation: L1D private per thread
> >
> > Output after fix:
> > # cat /sys/devices/system/cpu/vulnerabilities/meltdown
> > Mitigation: RFI Flush, L1D private per thread
> > # echo 0 > /sys/kernel/debug/powerpc/rfi_flush
> > # cat /sys/devices/system/cpu/vulnerabilities/meltdown
> > Vulnerable: L1D private per thread
> >
> > Link: https://github.com/linuxppc/issues/issues/243
> >
> > Signed-off-by: Gustavo L. F. Walbon <gwalbon@linux.ibm.com>
> > Signed-off-by: Mauro S. M. Rodrigues <maurosr@linux.vnet.ibm.com>
>
> Applied to powerpc next, thanks.
>
> https://git.kernel.org/powerpc/c/4e706af3cd8e1d0503c25332b30cad33c97ed442
>
> cheers
Fixes: ff348355e9c7 ("powerpc/64s: Enhance the information in
cpu_show_meltdown()")
Thanks
Michal
WARNING: multiple messages have this Message-ID (diff)
From: "Michal Suchánek" <msuchanek@suse.de>
To: Michael Ellerman <patch-notifications@ellerman.id.au>
Cc: mikey@neuling.org, maurosr@linux.vnet.ibm.com,
Gustavo Walbon <gwalbon@linux.ibm.com>,
linux-kernel@vger.kernel.org, npiggin@gmail.com,
diana.craciun@nxp.com, paulus@samba.org, stable@vger.kernel.org,
leitao@debian.org, linuxppc-dev@lists.ozlabs.org,
gwalbon@linux.vnet.ibm.com
Subject: Re: [PATCH] Fix wrong message when RFI Flush is disable
Date: Thu, 14 Nov 2019 10:31:38 +0100 [thread overview]
Message-ID: <20191114093138.GF11661@kitsune.suse.cz> (raw)
In-Reply-To: <47DFxM5mVHz9sNT@ozlabs.org>
On Thu, Nov 14, 2019 at 08:07:35PM +1100, Michael Ellerman wrote:
> On Thu, 2019-05-02 at 21:09:07 UTC, Gustavo Walbon wrote:
> > From: "Gustavo L. F. Walbon" <gwalbon@linux.ibm.com>
> >
> > The issue was showing "Mitigation" message via sysfs whatever the state of
> > "RFI Flush", but it should show "Vulnerable" when it is disabled.
> >
> > If you have "L1D private" feature enabled and not "RFI Flush" you are
> > vulnerable to meltdown attacks.
> >
> > "RFI Flush" is the key feature to mitigate the meltdown whatever the
> > "L1D private" state.
> >
> > SEC_FTR_L1D_THREAD_PRIV is a feature for Power9 only.
> >
> > So the message should be as the truth table shows.
> > CPU | L1D private | RFI Flush | sysfs |
> > ----| ----------- | --------- | ------------------------------------- |
> > P9 | False | False | Vulnerable
> > P9 | False | True | Mitigation: RFI Flush
> > P9 | True | False | Vulnerable: L1D private per thread
> > P9 | True | True | Mitigation: RFI Flush, L1D private per
> > | | | thread
> > P8 | False | False | Vulnerable
> > P8 | False | True | Mitigation: RFI Flush
> >
> > Output before this fix:
> > # cat /sys/devices/system/cpu/vulnerabilities/meltdown
> > Mitigation: RFI Flush, L1D private per thread
> > # echo 0 > /sys/kernel/debug/powerpc/rfi_flush
> > # cat /sys/devices/system/cpu/vulnerabilities/meltdown
> > Mitigation: L1D private per thread
> >
> > Output after fix:
> > # cat /sys/devices/system/cpu/vulnerabilities/meltdown
> > Mitigation: RFI Flush, L1D private per thread
> > # echo 0 > /sys/kernel/debug/powerpc/rfi_flush
> > # cat /sys/devices/system/cpu/vulnerabilities/meltdown
> > Vulnerable: L1D private per thread
> >
> > Link: https://github.com/linuxppc/issues/issues/243
> >
> > Signed-off-by: Gustavo L. F. Walbon <gwalbon@linux.ibm.com>
> > Signed-off-by: Mauro S. M. Rodrigues <maurosr@linux.vnet.ibm.com>
>
> Applied to powerpc next, thanks.
>
> https://git.kernel.org/powerpc/c/4e706af3cd8e1d0503c25332b30cad33c97ed442
>
> cheers
Fixes: ff348355e9c7 ("powerpc/64s: Enhance the information in
cpu_show_meltdown()")
Thanks
Michal
next prev parent reply other threads:[~2019-11-14 9:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-02 21:09 [PATCH] Fix wrong message when RFI Flush is disable Gustavo Walbon
2019-05-02 21:09 ` Gustavo Walbon
2019-11-14 9:07 ` Michael Ellerman
2019-11-14 9:31 ` Michal Suchánek [this message]
2019-11-14 9:31 ` Michal Suchánek
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