1 files changed, 71 insertions, 0 deletions
diff --git a/arch/powerpc/mm/vphn.c b/arch/powerpc/mm/vphn.c
new file mode 100644
index 000000000..f83044faa
--- /dev/null
+++ b/arch/powerpc/mm/vphn.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <asm/byteorder.h>
+#include "vphn.h"
+
+/*
+ * The associativity domain numbers are returned from the hypervisor as a
+ * stream of mixed 16-bit and 32-bit fields. The stream is terminated by the
+ * special value of "all ones" (aka. 0xffff) and its size may not exceed 48
+ * bytes.
+ *
+ *    --- 16-bit fields -->
+ *  _________________________
+ *  |  0  |  1  |  2  |  3  |   be_packed[0]
+ *  ------+-----+-----+------
+ *  _________________________
+ *  |  4  |  5  |  6  |  7  |   be_packed[1]
+ *  -------------------------
+ *            ...
+ *  _________________________
+ *  | 20  | 21  | 22  | 23  |   be_packed[5]
+ *  -------------------------
+ *
+ * Convert to the sequence they would appear in the ibm,associativity property.
+ */
+int vphn_unpack_associativity(const long *packed, __be32 *unpacked)
+{
+	__be64 be_packed[VPHN_REGISTER_COUNT];
+	int i, nr_assoc_doms = 0;
+	const __be16 *field = (const __be16 *) be_packed;
+	u16 last = 0;
+	bool is_32bit = false;
+
+#define VPHN_FIELD_UNUSED	(0xffff)
+#define VPHN_FIELD_MSB		(0x8000)
+#define VPHN_FIELD_MASK		(~VPHN_FIELD_MSB)
+
+	/* Let's fix the values returned by plpar_hcall9() */
+	for (i = 0; i < VPHN_REGISTER_COUNT; i++)
+		be_packed[i] = cpu_to_be64(packed[i]);
+
+	for (i = 1; i < VPHN_ASSOC_BUFSIZE; i++) {
+		u16 new = be16_to_cpup(field++);
+
+		if (is_32bit) {
+			/* Let's concatenate the 16 bits of this field to the
+			 * 15 lower bits of the previous field
+			 */
+			unpacked[++nr_assoc_doms] =
+				cpu_to_be32(last << 16 | new);
+			is_32bit = false;
+		} else if (new == VPHN_FIELD_UNUSED)
+			/* This is the list terminator */
+			break;
+		else if (new & VPHN_FIELD_MSB) {
+			/* Data is in the lower 15 bits of this field */
+			unpacked[++nr_assoc_doms] =
+				cpu_to_be32(new & VPHN_FIELD_MASK);
+		} else {
+			/* Data is in the lower 15 bits of this field
+			 * concatenated with the next 16 bit field
+			 */
+			last = new;
+			is_32bit = true;
+		}
+	}
+
+	/* The first cell contains the length of the property */
+	unpacked[0] = cpu_to_be32(nr_assoc_doms);
+
+	return nr_assoc_doms;
+}