[RFC 4/4] ppc/spapr: Advertise RTAS error injection call support via FDT property

[Narayana Murty N <nnmlinux@linux.ibm.com>]

Advertise RTAS error injection call support to guests through a new
"ibm,errinjct-tokens" property under the RTAS node in the device tree.

This patch introduces:
  - spapr_get_errinject_tokens(), which retrieves or constructs a blob
    of supported error injection tokens from the host or fallback data.
  - Integration of "ibm,errinjct-tokens" into the RTAS FDT node.
  - Addition of "ibm,open-errinjct" and "ibm,close-errinjct" properties
    to advertise open/close handlers for error injection sessions.

The ibm,errinjct-tokens property allows guests to programmatically
discover supported RTAS error injection facilities, enabling safe and
dynamic usage. The helper routine allocates memory for the token blob,
which the caller must free once it has been added to the FDT.

If the device-tree file (/proc/device-tree/rtas/ibm,errinjct-tokens)
is not available, a static fallback blob is generated internally.

Signed-off-by: Narayana Murty N <nnmlinux@linux.ibm.com>
---
 hw/ppc/spapr.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index e0a2e5a984..0ca8c777d5 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -114,6 +114,8 @@
 
 #define PHANDLE_INTC            0x00001111
 
+#define ERR_BLOB_MAX            512
+
 /* These two functions implement the VCPU id numbering: one to compute them
  * all and one to identify thread 0 of a VCORE. Any change to the first one
  * is likely to have an impact on the second one, so let's keep them close.
@@ -900,10 +902,104 @@ static int spapr_dt_rng(void *fdt)
     return ret ? -1 : 0;
 }
 
+/*
+ * spapr_get_errinject_tokens:
+ * ---------------------------
+ * Retrieve or construct a binary blob representing supported RTAS error
+ * injection tokens. If the host device-tree path
+ * "/proc/device-tree/rtas/ibm,errinjct-tokens" exists, it is read directly.
+ * Otherwise, a static fallback list of tokens is generated.
+ *
+ * The caller receives a dynamically allocated buffer in @out_buf and
+ * its size in @out_size, both of which must be freed by the caller
+ * once used.
+ *
+ * Returns:
+ *   0 (EXIT_SUCCESS)  - on success
+ *  -EIO, -ENOMEM      - on failure
+ */
+static int spapr_get_errinject_tokens(char **out_buf, size_t *out_size)
+{
+    char *path = NULL, *buf = NULL;
+    gsize len = 0;
+    uint8_t errinjct_blob[ERR_BLOB_MAX];
+
+    static const struct {
+        const char *name;
+        enum rtas_err_type token;
+    } errinjct_tokens[] = {
+        { "recovered-special-event", RTAS_ERR_TYPE_RECOVERED_SPECIAL_EVENT },
+        { "corrupted-page",          RTAS_ERR_TYPE_CORRUPTED_PAGE },
+        { "ioa-bus-error",           RTAS_ERR_TYPE_IOA_BUS_ERROR },
+        { "corrupted-dcache-start",  RTAS_ERR_TYPE_CORRUPTED_DCACHE_START },
+        { "corrupted-dcache-end",    RTAS_ERR_TYPE_CORRUPTED_DCACHE_END },
+        { "corrupted-icache-start",  RTAS_ERR_TYPE_CORRUPTED_ICACHE_START },
+        { "corrupted-icache-end",    RTAS_ERR_TYPE_CORRUPTED_ICACHE_END },
+        { "corrupted-tlb-start",     RTAS_ERR_TYPE_CORRUPTED_TLB_START },
+        { "corrupted-tlb-end",       RTAS_ERR_TYPE_CORRUPTED_TLB_END },
+        { "ioa-bus-error-64",        RTAS_ERR_TYPE_IOA_BUS_ERROR_64 },
+    };
+
+    path = g_strdup("/proc/device-tree/rtas/ibm,errinjct-tokens");
+
+    if (g_file_test(path, G_FILE_TEST_EXISTS)) {
+        qemu_log("RTAS: Found %s\n", path);
+
+        if (!g_file_get_contents(path, &buf, &len, NULL)) {
+            error_report("RTAS: Failed to read %s", path);
+            g_free(path);
+            return -EIO;
+        }
+
+        qemu_log("RTAS: Read %zu bytes from device-tree\n", len);
+        *out_buf = buf;
+        *out_size = len;
+        g_free(path);
+        return EXIT_SUCCESS;
+    }
+
+    qemu_log("RTAS: %s not found, building fallback blob\n", path);
+    g_free(path);
+    len = 0;
+
+    for (int i = 0; i < G_N_ELEMENTS(errinjct_tokens); i++) {
+        const char *name = errinjct_tokens[i].name;
+        size_t str_len = strlen(name) + 1;
+
+        if (len + str_len + sizeof(uint32_t) > sizeof(errinjct_blob)) {
+            error_report("RTAS: Too many tokens for static buffer");
+            return -ENOMEM;
+        }
+
+        memcpy(&errinjct_blob[len], name, str_len);
+        len += str_len;
+
+        uint32_t be_token = cpu_to_be32(errinjct_tokens[i].token);
+        memcpy(&errinjct_blob[len], &be_token, sizeof(be_token));
+        len += sizeof(be_token);
+    }
+
+    buf = g_malloc(len);
+    if (!buf) {
+        error_report("RTAS: Failed to allocate %zu bytes for blob", len);
+        return -ENOMEM;
+    }
+
+    memcpy(buf, errinjct_blob, len);
+    *out_buf = buf;
+    *out_size = len;
+
+    qemu_log("RTAS: Fallback blob built (%zu bytes)\n", len);
+    return EXIT_SUCCESS;
+}
+
+
 static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
 {
     MachineState *ms = MACHINE(spapr);
     int rtas;
+    size_t size_tokens = 0;
+    g_autofree char *errinject_tokens;
     GString *hypertas = g_string_sized_new(256);
     GString *qemu_hypertas = g_string_sized_new(256);
     uint64_t max_device_addr = 0;
@@ -1012,6 +1108,16 @@ static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
      */
     _FDT(fdt_setprop(fdt, rtas, "ibm,extended-os-term", NULL, 0));
 
+    if (!spapr_get_errinject_tokens(&errinject_tokens, &size_tokens)) {
+        _FDT(fdt_setprop(fdt, rtas, "ibm,errinjct-tokens",
+                         errinject_tokens, size_tokens));
+
+        _FDT(fdt_setprop_string(fdt, rtas, "ibm,open-errinjct",
+                                "ibm,open-errinjct"));
+        _FDT(fdt_setprop_string(fdt, rtas, "ibm,close-errinjct",
+                                "ibm,close-errinjct"));
+    }
+
     _FDT(fdt_setprop(fdt, rtas, "ibm,lrdr-capacity",
                      lrdr_capacity, sizeof(lrdr_capacity)));
 
-- 
2.51.0