KVM: VMX: Intercept reads to invalid and write-only x2APIC registers

KVM: VMX: Intercept reads to invalid and write-only x2APIC registers

Intercept reads to invalid (non-existent) and write-only x2APIC registers
when configuring VMX's MSR bitmaps for x2APIC+APICv.  When APICv is fully
enabled, Intel hardware doesn't validate the registers on RDMSR and
instead blindly retrieves data from the vAPIC page, i.e. it's software's
responsibility to intercept reads to non-existent and write-only MSRs.

Fixes: 8d14695f9542 ("x86, apicv: add virtual x2apic support")
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20230107011025.565472-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>