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Re: [PATCH for-4.2 1/2] i386: Add new versions of Skylake/Cascadelake/Ic
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From: |
Paolo Bonzini |
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Subject: |
Re: [PATCH for-4.2 1/2] i386: Add new versions of Skylake/Cascadelake/Icelake without TSX |
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Date: |
Wed, 20 Nov 2019 18:40:06 +0100 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 |
On 20/11/19 17:49, Eduardo Habkost 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.
What is the effect of this when using "-cpu CascadeLake-Server" and
upgrading QEMU? Would it automatically switch to the new version? If
so, would it be better to include a duplicate of the models (and if so,
that would conflict with my VMX features patch, which is also for 4.2).
Paolo