[PATCH v1 1/3] s390x: pv: implement routine to share/unshare memory

[Pierre Morel <pmorel@linux.ibm.com>]

When communicating with the host we need to share part of
the memory.

Let's implement the ultravisor calls for this.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Suggested-by: Janosch Frank <frankja@linux.ibm.com>
---
 lib/s390x/asm/uv.h | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/lib/s390x/asm/uv.h b/lib/s390x/asm/uv.h
index 4c2fc48..19019e4 100644
--- a/lib/s390x/asm/uv.h
+++ b/lib/s390x/asm/uv.h
@@ -71,4 +71,37 @@ static inline int uv_call(unsigned long r1, unsigned long r2)
 	return cc;
 }
 
+static inline int share(unsigned long addr, u16 cmd)
+{
+	struct uv_cb_share uvcb = {
+		.header.cmd = cmd,
+		.header.len = sizeof(uvcb),
+		.paddr = addr
+	};
+
+	uv_call(0, (u64)&uvcb);
+	return uvcb.header.rc;
+}
+
+/*
+ * Guest 2 request to the Ultravisor to make a page shared with the
+ * hypervisor for IO.
+ *
+ * @addr: Real or absolute address of the page to be shared
+ */
+static inline int uv_set_shared(unsigned long addr)
+{
+	return share(addr, UVC_CMD_SET_SHARED_ACCESS);
+}
+
+/*
+ * Guest 2 request to the Ultravisor to make a page unshared.
+ *
+ * @addr: Real or absolute address of the page to be unshared
+ */
+static inline int uv_remove_shared(unsigned long addr)
+{
+	return share(addr, UVC_CMD_REMOVE_SHARED_ACCESS);
+}
+
 #endif
-- 
2.25.1