x86/cpuid: Provide get_scattered_cpuid_leaf()

Sparse populated CPUID leafs are collected in a software provided leaf to
avoid bloat of the x86_capability array, but there is no way to rebuild the
real leafs (e.g. for KVM CPUID enumeration) other than rereading the CPUID
leaf from the CPU. While this is possible it is problematic as it does not
take software disabled features into account. If a feature is disabled on
the host it should not be exposed to a guest either.

Add get_scattered_cpuid_leaf() which rebuilds the leaf from the scattered
cpuid table information and the active CPU features.

[ tglx: Rewrote changelog ]

Signed-off-by: He Chen <[email protected]>
Reviewed-by: Borislav Petkov <[email protected]>
Cc: Luwei Kang <[email protected]>
Cc: [email protected]
Cc: Radim Krčmář <[email protected]>
Cc: Piotr Luc <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

0 files changed, 0 insertions, 0 deletions