From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Gustavo Walbon <gwalbon@linux.ibm.com>, linuxppc-dev@lists.ozlabs.org
Cc: 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,
msuchanek@suse.de, gwalbon@linux.vnet.ibm.com
Subject: Re: [PATCH] Fix wrong message when RFI Flush is disable
Date: Thu, 14 Nov 2019 20:07:35 +1100 (AEDT) [thread overview]
Message-ID: <47DFxM5mVHz9sNT@ozlabs.org> (raw)
In-Reply-To: <20190502210907.42375-1-gwalbon@linux.ibm.com>
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
next prev parent reply other threads:[~2019-11-14 9:07 UTC|newest]
Thread overview: 3+ 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
2019-11-14 9:07 ` Michael Ellerman [this message]
2019-11-14 9:31 ` Michal Suchánek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=47DFxM5mVHz9sNT@ozlabs.org \
--to=patch-notifications@ellerman.id.au \
--cc=diana.craciun@nxp.com \
--cc=gwalbon@linux.ibm.com \
--cc=gwalbon@linux.vnet.ibm.com \
--cc=leitao@debian.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=maurosr@linux.vnet.ibm.com \
--cc=mikey@neuling.org \
--cc=msuchanek@suse.de \
--cc=npiggin@gmail.com \
--cc=paulus@samba.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).