The current cpuid management suffers from several problems, which inhibit
passing through the host feature set to the guest:
- No way to tell which features the host supports
While some features can be supported with no changes to kvm, others
need explicit support. That means kvm needs to vet the feature set
before it is passed to the guest.
- No support for indexed or stateful cpuid entries
Some cpuid entries depend on ecx as well as on eax, or on internal
state in the processor (running cpuid multiple times with the same
input returns different output). The current cpuid machinery only
supports keying on eax.
- No support for save/restore/migrate
The internal state above needs to be exposed to userspace so it can
be saved or migrated.
This patch adds extended cpuid support by means of three new ioctls:
- KVM_GET_SUPPORTED_CPUID: get all cpuid entries the host (and kvm)
supports
- KVM_SET_CPUID2: sets the vcpu's cpuid table
- KVM_GET_CPUID2: gets the vcpu's cpuid table, including hidden state
[avi: fix original KVM_SET_CPUID not removing nx on non-nx hosts as it did
before]
Signed-off-by: Dan Kenigsberg <danken@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
