KVM: VMX: Do Hyper-V TLB flush iff vCPU's EPTP hasn't been flushed

Combine the for-loops for Hyper-V TLB EPTP checking and flushing, and in
doing so skip flushes for vCPUs whose EPTP matches the target EPTP.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305183123.3978098-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>