KVM: VMX: make MSR bitmaps per-VCPU

KVM: VMX: make MSR bitmaps per-VCPU

Place the MSR bitmap in struct loaded_vmcs, and update it in place
every time the x2apic or APICv state can change.  This is rare and
the loop can handle 64 MSRs per iteration, in a similar fashion as
nested_vmx_prepare_msr_bitmap.

This prepares for choosing, on a per-VM basis, whether to intercept
the SPEC_CTRL and PRED_CMD MSRs.

Cc: stable@vger.kernel.org       # prereq for Spectre mitigation
Suggested-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry-picked from 904e14fb7cb96401a7dc803ca2863fd5ba32ffe6)

Orabug: 28069548

Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>
Conflicts:
	arch/x86/kvm/vmx.c
Contextual - different content. Also vmx_enable_intercept_for_msr was already
in UEK4 as part of commit 8d14695f9542e9e0195d6e41ddaa52c32322adf5. We just
changed the signature.

Signed-off-by: Brian Maly <brian.maly@oracle.com>