MPIPL: Add OPAL API to query saved tags

Pre-MPIPL kernel saves various information required to create vmcore in
metadata area and passes metadata area pointer to OPAL. OPAL will preserve
this pointer across MPIPL. Post MPIPL kernel will request for saved tags
via this API. Kernel also needs below tags:
  - Saved CPU registers data to access CPU registers
  - OPAL metadata area to create opalcore

Format:
  opal_mpipl_query_tag(enum opal_mpipl_tags tag, uint64_t *tag_val)

  tag :
    OPAL_MPIPL_TAG_CPU
      Pointer to CPU register data content metadata area
    OPAL_MPIPL_TAG_OPAL
      Pointer to OPAL metadata area
    OPAL_MPIPL_TAG_KERNEL
      During first boot, kernel will setup its metadata area and asks
      OPAL to preserve metadata area pointer across MPIPL. Post MPIPL
      kernel calls this API to get metadata pointer and it will use
      that pointer to retrieve metadata and create dump.
    OPAL_MPIPL_TAG_BOOT_MEM
      During MPIPL registration kernel will specify how much memory
      firmware can use for Post MPIPL load. Post MPIPL petitboot kernel
      will query for this tag to get boot memory size.

Return values:
  OPAL_SUCCESS   : Operation success
  OPAL_PARAMETER : Invalid parameter

Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
[oliver: rebased]
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>

2 files changed, 43 insertions, 2 deletions

diff --git a/core/opal-dump.c b/core/opal-dump.c
index 15f8214..2ff3a2f 100644
--- a/core/opal-dump.c
+++ b/core/opal-dump.c
@@ -44,6 +44,18 @@ static struct mpipl_metadata    *mpipl_metadata;
 /* Dump metadata area */
 static struct opal_mpipl_fadump *opal_mpipl_data;
 
+/*
+ * Number of tags passed by OPAL to kernel after MPIPL boot.
+ * Currently it supports below tags:
+ *   - CPU register data area
+ *   - OPAL metadata area address
+ *   - Kernel passed tag during MPIPL registration
+ *   - Post MPIPL boot memory size
+ */
+#define MAX_OPAL_MPIPL_TAGS	0x04
+static u64 opal_mpipl_tags[MAX_OPAL_MPIPL_TAGS];
+static int opal_mpipl_max_tags = MAX_OPAL_MPIPL_TAGS;
+
 
 static int opal_mpipl_add_entry(u8 region, u64 src, u64 dest, u64 size)
 {
@@ -333,6 +345,29 @@ static int64_t opal_mpipl_register_tag(enum opal_mpipl_tags tag,
 	return rc;
 }
 
+static uint64_t opal_mpipl_query_tag(enum opal_mpipl_tags tag,
+				     uint64_t *tag_val)
+{
+	if (!opal_addr_valid(tag_val)) {
+		prlog(PR_DEBUG, "Invalid tag address\n");
+		return OPAL_PARAMETER;
+	}
+
+	if (tag >= opal_mpipl_max_tags)
+		return OPAL_PARAMETER;
+
+	*tag_val = opal_mpipl_tags[tag];
+	return OPAL_SUCCESS;
+}
+
+static inline void post_mpipl_get_preserved_tags(void)
+{
+	if (mpipl_metadata->kernel_tag)
+		opal_mpipl_tags[OPAL_MPIPL_TAG_KERNEL] = mpipl_metadata->kernel_tag;
+	if (mpipl_metadata->boot_mem_size)
+		opal_mpipl_tags[OPAL_MPIPL_TAG_BOOT_MEM] = mpipl_metadata->boot_mem_size;
+}
+
 static void post_mpipl_get_opal_data(void)
 {
 	struct mdrt_table *mdrt = (void *)(MDRT_TABLE_BASE);
@@ -385,6 +420,8 @@ static void post_mpipl_get_opal_data(void)
 		if (j == count)
 			break;
 	}
+
+	opal_mpipl_tags[OPAL_MPIPL_TAG_OPAL] = (u64)opal_mpipl_data;
 }
 
 void opal_mpipl_save_crashing_pir(void)
@@ -411,8 +448,10 @@ void opal_mpipl_init(void)
 	/* Get metadata area pointer */
 	mpipl_metadata = (void *)(DUMP_METADATA_AREA_BASE);
 
-	if (dt_find_property(dump_node, "mpipl-boot"))
+	if (dt_find_property(dump_node, "mpipl-boot")) {
+		post_mpipl_get_preserved_tags();
 		post_mpipl_get_opal_data();
+	}
 
 	/* Clear OPAL metadata area */
 	if (sizeof(struct mpipl_metadata) > DUMP_METADATA_AREA_SIZE) {
@@ -436,4 +475,5 @@ void opal_mpipl_init(void)
 	/* OPAL API for MPIPL update */
 	opal_register(OPAL_MPIPL_UPDATE, opal_mpipl_update, 4);
 	opal_register(OPAL_MPIPL_REGISTER_TAG, opal_mpipl_register_tag, 2);
+	opal_register(OPAL_MPIPL_QUERY_TAG, opal_mpipl_query_tag, 2);
 }
diff --git a/include/opal-api.h b/include/opal-api.h
index 7d8e046..ee66bbb 100644
--- a/include/opal-api.h
+++ b/include/opal-api.h
@@ -221,7 +221,8 @@
 #define OPAL_NPU_MEM_RELEASE			172
 #define OPAL_MPIPL_UPDATE			173
 #define OPAL_MPIPL_REGISTER_TAG			174
-#define OPAL_LAST				174
+#define OPAL_MPIPL_QUERY_TAG			175
+#define OPAL_LAST				175
 
 #define QUIESCE_HOLD			1 /* Spin all calls at entry */
 #define QUIESCE_REJECT			2 /* Fail all calls with OPAL_BUSY */