Merge branch 'kvm-vmenter' into HEAD

Merge branch 'kvm-vmenter' into HEAD

Move SPEC_CTRL handling for VMX entirely to vmenter.S, also improving
assembly code reuse between SVM and VMX.

The prototype of __vmx_vcpu_run() and __svm_vcpu_run() becomes
the same, with a set of bit flags for the second argument.
The register allocation also becomes very similar, with %edi/%rdi
pointing to the vmx (resp. svm) argument.

Thanks to this, the code to save and restore SPEC_CTRL values for the
host and guest is the same up to the register names and can be dropped
into a new header arch/x86/kvm/vmenter.h.  APX enablement will also move
common code to load and save registers from VMX and SVM to vmenter.h.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>