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Re: [Qemu-devel] [PATCH] WHPX Add signature CPUID
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH] WHPX Add signature CPUID |
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Date: |
Wed, 16 May 2018 09:34:52 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
On 16/05/2018 01:55, Alessandro Pilotti wrote:
> Hi Paolo,
>
> The main reason for different signatures is to allow guest workloads
> to be aware of the differences between the two platforms (eg VirtIO
> vs VMBus).
Why does it matter? CPUID tells you about the enlightenments that the
hypervisor provides, not the availability of the VMBus.
VMBus requires some of the enlightenments, mostly related to the
synthetic interrupt controllers, but the opposite is not true---you can
have enlightenments without VMBus, and in fact you probably want WHPX to
enable the relaxed timing enlightenment.
Thanks,
Paolo