KVM: PPC: Book3S PR: Support TAR handling for PR KVM HTM

Currently guest kernel doesn't handle TAR facility unavailable and it
always runs with TAR bit on. PR KVM will lazily enable TAR. TAR is not
a frequent-use register and it is not included in SVCPU struct.

Due to the above, the checkpointed TAR val might be a bogus TAR val.
To solve this issue, we will make vcpu->arch.fscr tar bit consistent
with shadow_fscr when TM is enabled.

At the end of emulating treclaim., the correct TAR val need to be loaded
into the register if FSCR_TAR bit is on.

At the beginning of emulating trechkpt., TAR needs to be flushed so that
the right tar val can be copied into tar_tm.

Tested with:
tools/testing/selftests/powerpc/tm/tm-tar
tools/testing/selftests/powerpc/ptrace/ptrace-tm-tar (remove DSCR/PPR
related testing).

Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/include/asm/kvm_book3s.h

@@ -271,6 +271,8 @@ static inline void kvmppc_save_tm_sprs(struct kvm_vcpu *vcpu) {}
 static inline void kvmppc_restore_tm_sprs(struct kvm_vcpu *vcpu) {}
 #endif
 
+void kvmppc_giveup_fac(struct kvm_vcpu *vcpu, ulong fac);
+
 extern int kvm_irq_bypass;
 
 static inline struct kvmppc_vcpu_book3s *to_book3s(struct kvm_vcpu *vcpu)