KVM: e500: use shadow TLB entry as witness for writability

kvmppc_e500_ref_setup is returning whether the guest TLB entry is writable,
which is than passed to kvm_release_faultin_page. This makes little sense
for two reasons: first, because the function sets up the private data for
the page and the return value feels like it has been bolted on the side;
second, because what really matters is whether the _shadow_ TLB entry is
writable. If it is not writable, the page can be released as non-dirty.
Shift from using tlbe_is_writable(gtlbe) to doing the same check on
the shadow TLB entry.

Signed-off-by: Paolo Bonzini <[e-mail]>

arch/powerpc/kvm/e500_mmu_host.c

···
 	return tlbe->mas7_3 & (MAS3_SW|MAS3_UW);
 }
 
-static inline bool kvmppc_e500_ref_setup(struct tlbe_ref *ref,
+static inline void kvmppc_e500_ref_setup(struct tlbe_ref *ref,
 					 struct kvm_book3e_206_tlb_entry *gtlbe,
 					 kvm_pfn_t pfn, unsigned int wimg)
 {
···
 
 	/* Use guest supplied MAS2_G and MAS2_E */
 	ref->flags |= (gtlbe->mas2 & MAS2_ATTRIB_MASK) | wimg;
-
-	return tlbe_is_writable(gtlbe);
 }
 
 static inline void kvmppc_e500_ref_release(struct tlbe_ref *ref)
···
 	}
 	local_irq_restore(flags);
 
-	writable = kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg);
+	kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg);
 	kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize,
 				ref, gvaddr, stlbe);
+	writable = tlbe_is_writable(stlbe);
 
 	/* Clear i-cache for new pages */
 	kvmppc_mmu_flush_icache(pfn);