powerpc/powernv: Enable TM without suspend if possible

Some Power9 revisions can run in a mode where TM operates without
suspended state. If we find ourself on a CPU that might be in this
mode, we query OPAL to check, and if so we reenable TM in CPU
features, and enable a new user feature to signal to userspace that we
are in this mode.

We do not enable the "normal" user feature, PPC_FEATURE2_HTM, but we
do enable PPC_FEATURE2_HTM_NOSC because that indicates to userspace
that the kernel will abort transactions on syscall entry, which is
true regardless of the suspend mode.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/powernv.h

@@ -22,6 +22,8 @@ extern void pnv_npu2_destroy_context(struct npu_context *context,
 extern int pnv_npu2_handle_fault(struct npu_context *context, uintptr_t *ea,
 				unsigned long *flags, unsigned long *status,
 				int count);
+
+void pnv_tm_init(void);
 #else
 static inline void powernv_set_nmmu_ptcr(unsigned long ptcr) { }
 static inline struct npu_context *pnv_npu2_init_context(struct pci_dev *gpdev,
@@ -36,6 +38,8 @@ static inline int pnv_npu2_handle_fault(struct npu_context *context,
 					unsigned long *status, int count) {
 	return -ENODEV;
 }
+
+static inline void pnv_tm_init(void) { }
 #endif
 
 #endif /* _ASM_POWERNV_H */