Mailinglist Archive: opensuse-factory (439 mails)

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Re: [opensuse-factory] Huge single-core performance loss with spectre v2 mitigation enabled (it's the default)
On Wed, 2019-04-10 at 13:31 +0200, Jiri Slaby wrote:
On 10. 04. 19, 12:31, Michael Pujos wrote:

spectre_v2=retpoline,generic should be the default in my opinion.
If
good guys at Fedora (and other distros) are using it, so can
openSUSE.

They don't even have IBRS support in their kernels AFAIR.

FWIW, they seem to have that now, at least, according to this:

Fedora default: http://termbin.com/0u7o
* Kernel is compiled with IBRS support: YES
* IBRS enabled and active: YES (for kernel and firmware code)

Out of curiosity, I installed kernel-vanilla on Tumbleweed, and there I
have:

$ cat /sys/devices/system/cpu/vulnerabilities/spectre_v2
Mitigation: Full generic retpoline, IBPB: conditional, IBRS_FW, STIBP:
conditional, RSB filling

# sudo spectre-meltdown-checker.sh
...
CVE-2017-5715 aka 'Spectre Variant 2, branch target injection'
* Mitigation 2
STATUS: NOT VULNERABLE (Full retpoline + IBPB are mitigating the
vulnerability)

Which confirms (if there were any need for that) that it's our own
doing, e.g., in kernel-default...

retpolines are not complete protection on skylake+.

... For this reason, indeed. :-)

Regards
--
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
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<<This happens because _I_ choose it to happen!>> (Raistlin Majere)

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