powerpc/xive: Fix compile when !CONFIG_PPC_POWERNV.

The automatic "save & restore" of interrupt context is a POWER10/XIVE2
feature exploited by KVM under the PowerNV platform. It is not
available under pSeries and the associated toggle should not be
exposed under the XIVE debugfs directory.

Introduce a platform handler for debugfs initialization and move the
'save-restore' entry under the native (PowerNV) backend to fix compile
when !CONFIG_PPC_POWERNV.

Fixes: 1e7684dc ("powerpc/xive: Add a debugfs toggle for save-restore")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201165418.1041842-1-clg@kaod.org

arch/powerpc/sysdev/xive/common.c

@@ -1847,7 +1847,9 @@ static void xive_core_debugfs_create(void)
 				    &xive_eq_debug_fops);
 	}
 	debugfs_create_bool("store-eoi", 0600, xive_dir, &xive_store_eoi);
-	debugfs_create_bool("save-restore", 0600, xive_dir, &xive_has_save_restore);
+
+	if (xive_ops->debug_create)
+		xive_ops->debug_create(xive_dir);
 }
 #else
 static inline void xive_core_debugfs_create(void) { }

arch/powerpc/sysdev/xive/native.c

@@ -461,6 +461,14 @@ void xive_native_sync_queue(u32 hw_irq)
 }
 EXPORT_SYMBOL_GPL(xive_native_sync_queue);
 
+#ifdef CONFIG_DEBUG_FS
+static int xive_native_debug_create(struct dentry *xive_dir)
+{
+	debugfs_create_bool("save-restore", 0600, xive_dir, &xive_has_save_restore);
+	return 0;
+}
+#endif
+
 static const struct xive_ops xive_native_ops = {
 	.populate_irq_data	= xive_native_populate_irq_data,
 	.configure_irq		= xive_native_configure_irq,
@@ -478,6 +486,9 @@ static const struct xive_ops xive_native_ops = {
 	.get_ipi		= xive_native_get_ipi,
 	.put_ipi		= xive_native_put_ipi,
 #endif /* CONFIG_SMP */
+#ifdef CONFIG_DEBUG_FS
+	.debug_create		= xive_native_debug_create,
+#endif /* CONFIG_DEBUG_FS */
 	.name			= "native",
 };
 

arch/powerpc/sysdev/xive/xive-internal.h

@@ -58,6 +58,7 @@ struct xive_ops {
 	void	(*put_ipi)(unsigned int cpu, struct xive_cpu *xc);
 #endif
 	int	(*debug_show)(struct seq_file *m, void *private);
+	int	(*debug_create)(struct dentry *xive_dir);
 	const char *name;
 };