Messages in this thread | | | Date | Tue, 27 Apr 2010 22:20:52 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH 4/6] export new cpuid KVM_CAP |
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On 04/27/2010 10:09 PM, Glauber Costa wrote: > >> Hmm. We already have an API to get cpuid bits: >> KVM_GET_SUPPORTED_CPUID2. The nice thing about it is that it will >> mean -cpu host will work out of the box. >> > Ok, from what I understand, KVM_GET_CPUID2 gets a set of features, and tells > userspace which of them are available. Right? >
No. KVM_GET_CPUID2 reads what was set by KVM_SET_CPUID, as modified by the guest executing the cpuid instruction. KVM_GET_SUPPORTED_CPUID tells userspace which bits are supported by the host cpu and kvm.
> If this is the case, userspace could ask for 0xffffffff, and then we tell them > which of them are present. > > Does that make sense? >
The API for KVM_GET_SUPPORTED_CPUID returns all cpuid leaves supported in one go, IIRC.
-- Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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