linux-kernel - Question about mitigating Zombieload

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Message-ID: <0YYNF4UDAi1NJOBtzDhwqt1FJ_3NzTYIvtu2ApVMMPsEH0cfm9OMgYJpVHd8w0pfmeQCScYO5x-PlvdbNnnERNKiYMhEw1z3hQPaFRwvVOM=@protonmail.com>
Date:   Thu, 30 May 2019 17:29:48 +0000
From:   zvuln <zvuln@...tonmail.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Question about mitigating Zombieload

It seems the x86 architecture is once again
afflicted with a flaw that arises out of
unsafely implemented accelerations, namely
the just-releaved Zombieload vulnerability.

We know that Zombieload is possible when
Hyperthreading is enabled. Here is a question:

Is it possible to disable Hyperthreading
not for all cores in the BIOS but rather
on a per-core basis programmatically from
the OS or from the bootloader?

I ask because if this were possible, then
it would be reasonable to segregate the sensitive
code i.e. the kernel and the major daemons
into one core that has Hyperthreading enabled,
and then run all other (risky) user processes
on the other cores, which have Hyperthreading
disabled.

Cheers.