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





On Tue, Mar 10, 2020 at 11:48 AM Christian Ehrhardt <christian ehrhardt 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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