KVM: Introduce paravirtualization hints and KVM_HINTS_DEDICATED

This patch introduces kvm_para_has_hint() to query for hints about
the configuration of the guests.  The first hint KVM_HINTS_DEDICATED,
is set if the guest has dedicated physical CPUs for each vCPU (i.e.
pinning and no over-commitment).  This allows optimizing spinlocks
and tells the guest to avoid PV TLB flush.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

arch/powerpc/include/asm/kvm_para.h

@@ -61,6 +61,11 @@ static inline unsigned int kvm_arch_para_features(void)
 	return r;
 }
 
+static inline unsigned int kvm_arch_para_hints(void)
+{
+	return 0;
+}
+
 static inline bool kvm_check_and_clear_guest_paused(void)
 {
 	return false;