KVM: VMX: Stuff vcpu->arch.apic_base directly at vCPU RESET

KVM: VMX: Stuff vcpu->arch.apic_base directly at vCPU RESET

Write vcpu->arch.apic_base directly instead of bouncing through
kvm_set_apic_base().  This is a glorified nop, and is a step towards
cleaning up the mess that is local APIC creation.

When using an in-kernel APIC, kvm_create_lapic() explicitly sets
vcpu->arch.apic_base to MSR_IA32_APICBASE_ENABLE to avoid its own
kvm_lapic_set_base() call in kvm_lapic_reset() from triggering state
changes.  That call during RESET exists purely to set apic->base_address
to the default base value.  As a result, by the time VMX gets control,
the only missing piece is the BSP bit being set for the reset BSP.

For a userspace APIC, there are no side effects to process (for the APIC).

In both cases, the call to kvm_update_cpuid_runtime() is a nop because
the vCPU hasn't yet been exposed to userspace, i.e. there can't be any
CPUID entries.

No functional change intended.

Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>