spapr_ovec: initial implementation of option vector helpers

PAPR guests advertise their capabilities to the platform by passing
an ibm,architecture-vec structure via an
ibm,client-architecture-support hcall as described by LoPAPR v11,
B.6.2.3. during early boot.

Using this information, the platform enables the capabilities it
supports, then encodes a subset of those enabled capabilities (the
5th option vector of the ibm,architecture-vec structure passed to
ibm,client-architecture-support) into the guest device tree via
"/chosen/ibm,architecture-vec-5".

The logical format of these these option vectors is a bit-vector,
where individual bits are addressed/documented based on the byte-wise
offset from the beginning of the bit-vector, followed by the bit-wise
index starting from the byte-wise offset. Thus the bits of each of
these bytes are stored in reverse order. Additionally, the first
byte of each option vector is encodes the length of the option vector,
so byte offsets begin at 1, and bit offset at 0.

This is not very intuitive for the purposes of mapping these bits to
a particular documented capability, so this patch introduces a set
of abstractions that encapsulate the work of parsing/encoding these
options vectors and testing for individual capabilities.

Cc: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
[dwg: Tweaked double-include protection to not trigger a checkpatch
 false positive]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 242 insertions, 0 deletions

diff --git a/hw/ppc/spapr_ovec.c b/hw/ppc/spapr_ovec.c
new file mode 100644
index 0000000000..c2a0d18577
--- /dev/null
+++ b/hw/ppc/spapr_ovec.c
@@ -0,0 +1,242 @@
+/*
+ * QEMU SPAPR Architecture Option Vector Helper Functions
+ *
+ * Copyright IBM Corp. 2016
+ *
+ * Authors:
+ *  Bharata B Rao     <bharata@linux.vnet.ibm.com>
+ *  Michael Roth      <mdroth@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/ppc/spapr_ovec.h"
+#include "qemu/bitmap.h"
+#include "exec/address-spaces.h"
+#include "qemu/error-report.h"
+#include <libfdt.h>
+
+/* #define DEBUG_SPAPR_OVEC */
+
+#ifdef DEBUG_SPAPR_OVEC
+#define DPRINTFN(fmt, ...) \
+    do { fprintf(stderr, fmt "\n", ## __VA_ARGS__); } while (0)
+#else
+#define DPRINTFN(fmt, ...) \
+    do { } while (0)
+#endif
+
+#define OV_MAXBYTES 256 /* not including length byte */
+#define OV_MAXBITS (OV_MAXBYTES * BITS_PER_BYTE)
+
+/* we *could* work with bitmaps directly, but handling the bitmap privately
+ * allows us to more safely make assumptions about the bitmap size and
+ * simplify the calling code somewhat
+ */
+struct sPAPROptionVector {
+    unsigned long *bitmap;
+};
+
+sPAPROptionVector *spapr_ovec_new(void)
+{
+    sPAPROptionVector *ov;
+
+    ov = g_new0(sPAPROptionVector, 1);
+    ov->bitmap = bitmap_new(OV_MAXBITS);
+
+    return ov;
+}
+
+sPAPROptionVector *spapr_ovec_clone(sPAPROptionVector *ov_orig)
+{
+    sPAPROptionVector *ov;
+
+    g_assert(ov_orig);
+
+    ov = spapr_ovec_new();
+    bitmap_copy(ov->bitmap, ov_orig->bitmap, OV_MAXBITS);
+
+    return ov;
+}
+
+void spapr_ovec_intersect(sPAPROptionVector *ov,
+                          sPAPROptionVector *ov1,
+                          sPAPROptionVector *ov2)
+{
+    g_assert(ov);
+    g_assert(ov1);
+    g_assert(ov2);
+
+    bitmap_and(ov->bitmap, ov1->bitmap, ov2->bitmap, OV_MAXBITS);
+}
+
+/* returns true if options bits were removed, false otherwise */
+bool spapr_ovec_diff(sPAPROptionVector *ov,
+                     sPAPROptionVector *ov_old,
+                     sPAPROptionVector *ov_new)
+{
+    unsigned long *change_mask = bitmap_new(OV_MAXBITS);
+    unsigned long *removed_bits = bitmap_new(OV_MAXBITS);
+    bool bits_were_removed = false;
+
+    g_assert(ov);
+    g_assert(ov_old);
+    g_assert(ov_new);
+
+    bitmap_xor(change_mask, ov_old->bitmap, ov_new->bitmap, OV_MAXBITS);
+    bitmap_and(ov->bitmap, ov_new->bitmap, change_mask, OV_MAXBITS);
+    bitmap_and(removed_bits, ov_old->bitmap, change_mask, OV_MAXBITS);
+
+    if (!bitmap_empty(removed_bits, OV_MAXBITS)) {
+        bits_were_removed = true;
+    }
+
+    g_free(change_mask);
+    g_free(removed_bits);
+
+    return bits_were_removed;
+}
+
+void spapr_ovec_cleanup(sPAPROptionVector *ov)
+{
+    if (ov) {
+        g_free(ov->bitmap);
+        g_free(ov);
+    }
+}
+
+void spapr_ovec_set(sPAPROptionVector *ov, long bitnr)
+{
+    g_assert(ov);
+    g_assert_cmpint(bitnr, <, OV_MAXBITS);
+
+    set_bit(bitnr, ov->bitmap);
+}
+
+void spapr_ovec_clear(sPAPROptionVector *ov, long bitnr)
+{
+    g_assert(ov);
+    g_assert_cmpint(bitnr, <, OV_MAXBITS);
+
+    clear_bit(bitnr, ov->bitmap);
+}
+
+bool spapr_ovec_test(sPAPROptionVector *ov, long bitnr)
+{
+    g_assert(ov);
+    g_assert_cmpint(bitnr, <, OV_MAXBITS);
+
+    return test_bit(bitnr, ov->bitmap) ? true : false;
+}
+
+static void guest_byte_to_bitmap(uint8_t entry, unsigned long *bitmap,
+                                 long bitmap_offset)
+{
+    int i;
+
+    for (i = 0; i < BITS_PER_BYTE; i++) {
+        if (entry & (1 << (BITS_PER_BYTE - 1 - i))) {
+            bitmap_set(bitmap, bitmap_offset + i, 1);
+        }
+    }
+}
+
+static uint8_t guest_byte_from_bitmap(unsigned long *bitmap, long bitmap_offset)
+{
+    uint8_t entry = 0;
+    int i;
+
+    for (i = 0; i < BITS_PER_BYTE; i++) {
+        if (test_bit(bitmap_offset + i, bitmap)) {
+            entry |= (1 << (BITS_PER_BYTE - 1 - i));
+        }
+    }
+
+    return entry;
+}
+
+static target_ulong vector_addr(target_ulong table_addr, int vector)
+{
+    uint16_t vector_count, vector_len;
+    int i;
+
+    vector_count = ldub_phys(&address_space_memory, table_addr) + 1;
+    if (vector > vector_count) {
+        return 0;
+    }
+    table_addr++; /* skip nr option vectors */
+
+    for (i = 0; i < vector - 1; i++) {
+        vector_len = ldub_phys(&address_space_memory, table_addr) + 1;
+        table_addr += vector_len + 1; /* bit-vector + length byte */
+    }
+    return table_addr;
+}
+
+sPAPROptionVector *spapr_ovec_parse_vector(target_ulong table_addr, int vector)
+{
+    sPAPROptionVector *ov;
+    target_ulong addr;
+    uint16_t vector_len;
+    int i;
+
+    g_assert(table_addr);
+    g_assert_cmpint(vector, >=, 1); /* vector numbering starts at 1 */
+
+    addr = vector_addr(table_addr, vector);
+    if (!addr) {
+        /* specified vector isn't present */
+        return NULL;
+    }
+
+    vector_len = ldub_phys(&address_space_memory, addr++) + 1;
+    g_assert_cmpint(vector_len, <=, OV_MAXBYTES);
+    ov = spapr_ovec_new();
+
+    for (i = 0; i < vector_len; i++) {
+        uint8_t entry = ldub_phys(&address_space_memory, addr + i);
+        if (entry) {
+            DPRINTFN("read guest vector %2d, byte %3d / %3d: 0x%.2x",
+                     vector, i + 1, vector_len, entry);
+            guest_byte_to_bitmap(entry, ov->bitmap, i * BITS_PER_BYTE);
+        }
+    }
+
+    return ov;
+}
+
+int spapr_ovec_populate_dt(void *fdt, int fdt_offset,
+                           sPAPROptionVector *ov, const char *name)
+{
+    uint8_t vec[OV_MAXBYTES + 1];
+    uint16_t vec_len;
+    unsigned long lastbit;
+    int i;
+
+    g_assert(ov);
+
+    lastbit = find_last_bit(ov->bitmap, OV_MAXBITS);
+    /* if no bits are set, include at least 1 byte of the vector so we can
+     * still encoded this in the device tree while abiding by the same
+     * encoding/sizing expected in ibm,client-architecture-support
+     */
+    vec_len = (lastbit == OV_MAXBITS) ? 1 : lastbit / BITS_PER_BYTE + 1;
+    g_assert_cmpint(vec_len, <=, OV_MAXBYTES);
+    /* guest expects vector len encoded as vec_len - 1, since the length byte
+     * is assumed and not included, and the first byte of the vector
+     * is assumed as well
+     */
+    vec[0] = vec_len - 1;
+
+    for (i = 1; i < vec_len + 1; i++) {
+        vec[i] = guest_byte_from_bitmap(ov->bitmap, (i - 1) * BITS_PER_BYTE);
+        if (vec[i]) {
+            DPRINTFN("encoding guest vector byte %3d / %3d: 0x%.2x",
+                     i, vec_len, vec[i]);
+        }
+    }
+
+    return fdt_setprop(fdt, fdt_offset, name, vec, vec_len);
+}