[PATCH 2/2] xen: wrap privcmd on xenfs with COMPAT option

[Doug Goldstein <cardoe@cardoe.com>]

Since Xen 4.7.0, using privcmd via xenfs (/proc/xen/privcmd) is deprecated
and /dev/xen/privcmd via pvops is used instead. This is an effort to
eventually drop this interface after a reasonable amount of time.

Signed-off-by: Doug Goldstein <cardoe@cardoe.com>
---
 drivers/xen/Kconfig       | 12 ++++++++++++
 drivers/xen/xenfs/super.c |  4 ++++
 2 files changed, 16 insertions(+)

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 7003984..c610902 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -135,6 +135,18 @@ config XEN_COMPAT_XENFS_XENBUS
 	  Xen 4.6.0 and newer.
 	  If in doubt, say yes.
 
+config XEN_COMPAT_XENFS_PRIVCMD
+	bool "privcmd accessible from xenfs"
+	depends on XENFS
+	default y
+	help
+	  Since Xen 4.7.0, Xen userland will prefer to use the
+	  /dev/xen/privcmd device over the "privcmd" interface on the
+	  xenfs filesystem. Selecting this causes the kernel to include
+	  the "privcmd" interface on the xenfs filesystem and you can
+	  safely say no for Xen 4.7.0 and newer.
+	  If in doubt, say yes.
+
 config XEN_SYS_HYPERVISOR
        bool "Create xen entries under /sys/hypervisor"
        depends on SYSFS
diff --git a/drivers/xen/xenfs/super.c b/drivers/xen/xenfs/super.c
index 86ff5b3..bb40970b 100644
--- a/drivers/xen/xenfs/super.c
+++ b/drivers/xen/xenfs/super.c
@@ -50,7 +50,9 @@ static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
 		{ "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
 #endif
 		{ "capabilities", &capabilities_file_ops, S_IRUGO },
+#ifdef CONFIG_XEN_COMPAT_XENFS_PRIVCMD
 		{ "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
+#endif
 		{""},
 	};
 
@@ -60,7 +62,9 @@ static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
 		{ "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
 #endif
 		{ "capabilities", &capabilities_file_ops, S_IRUGO },
+#ifdef CONFIG_XEN_COMPAT_XENFS_PRIVCMD
 		{ "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
+#endif
 		{ "xsd_kva", &xsd_kva_file_ops, S_IRUSR|S_IWUSR},
 		{ "xsd_port", &xsd_port_file_ops, S_IRUSR|S_IWUSR},
 #ifdef CONFIG_XEN_SYMS
-- 
2.4.10