[PATCH v2 1/1] cpu_map: Add more -noTSX x86 CPU models

Christian Ehrhardt christian.ehrhardt at canonical.com
Fri Mar 13 08:45:15 UTC 2020


On Tue, Mar 10, 2020 at 11:48 AM Christian Ehrhardt <
christian.ehrhardt at canonical.com> wrote:

> One of the mitigation methods for TAA[1] is to disable TSX
> support on the host system.  Linux added a mechanism to disable
> TSX globally through the kernel command line, and many Linux
> distributions now default to tsx=off.  This makes existing CPU
> models that have HLE and RTM enabled not usable anymore.
>
> Add new versions of all CPU models that have the HLE and RTM
> features enabled, that can be used when TSX is disabled in the
> host system.
>
> On systems disabling the features without those types defined
> in cpu-maps users end up without modern CPU types in the list
> of usable CPUs to use in the likes of virsh domcapabilities
> or tools higher in the stack like virt-manager.
>
> This adds:
> -Cascadelake-Server-noTSX
> -Icelake-Client-noTSX
> -Icelake-Server-noTSX
> -Skylake-Server-noTSX-IBRS
> -Skylake-Client-noTSX-IBRS
>
> Introduced in QEMU by commit v4.2.0-rc2-3-g9ab2237f19 (function)
>                   and commit v4.2.0-rc2-4-g02fa60d101 (names)
>

Ping - anything else that we need for this v2 right now to accept it?

I know in the long run Jiri would want to auto-select the non noTSX types.
But as I outlined before I'd consider this a later change or would need
some guidance where/how it is envisioned to do tat preference.
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