linux-kernel - [PATCH v3] powerpc/pseries: read the lpar name from the firmware

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Message-Id: <20211203154321.13168-1-ldufour@linux.ibm.com>
Date:   Fri,  3 Dec 2021 16:43:21 +0100
From:   Laurent Dufour <ldufour@...ux.ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org
Cc:     linux-kernel@...r.kernel.org, Nathan Lynch <nathanl@...ux.ibm.com>
Subject: [PATCH v3] powerpc/pseries: read the lpar name from the firmware

The LPAR name may be changed after the LPAR has been started in the HMC.
In that case lparstat command is not reporting the updated value because it
reads it from the device tree which is read at boot time.

However this value could be read from RTAS.

Adding this value in the /proc/powerpc/lparcfg output allows to read the
updated value.

Cc: Nathan Lynch <nathanl@...ux.ibm.com>
Signed-off-by: Laurent Dufour <ldufour@...ux.ibm.com>
---
v3:
 address Michael's comments.
v2:
 address Nathan's comments.
 change title to partition_name aligning with existing partition_id
---
 arch/powerpc/platforms/pseries/lparcfg.c | 54 ++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
index f71eac74ea92..5f6dbc23d7d2 100644
--- a/arch/powerpc/platforms/pseries/lparcfg.c
+++ b/arch/powerpc/platforms/pseries/lparcfg.c
@@ -311,6 +311,59 @@ static void parse_mpp_x_data(struct seq_file *m)
 		seq_printf(m, "coalesce_pool_spurr=%ld\n", mpp_x_data.pool_spurr_cycles);
 }
 
+/*
+ * PAPR defines, in section "7.3.16 System Parameters Option", the token 55 to
+ * read the LPAR name.
+ */
+#define SPLPAR_LPAR_NAME_TOKEN	55
+static void read_lpar_name(struct seq_file *m)
+{
+	int rc, len, token;
+	union {
+		char raw_buffer[RTAS_DATA_BUF_SIZE];
+		struct {
+			__be16 len;
+			char name[RTAS_DATA_BUF_SIZE-2];
+		};
+	} *local_buffer;
+
+	token = rtas_token("ibm,get-system-parameter");
+	if (token == RTAS_UNKNOWN_SERVICE)
+		return;
+
+	local_buffer = kmalloc(sizeof(*local_buffer), GFP_KERNEL);
+	if (!local_buffer)
+		return;
+
+	do {
+		spin_lock(&rtas_data_buf_lock);
+		memset(rtas_data_buf, 0, RTAS_DATA_BUF_SIZE);
+		rc = rtas_call(token, 3, 1, NULL, SPLPAR_LPAR_NAME_TOKEN,
+			       __pa(rtas_data_buf), RTAS_DATA_BUF_SIZE);
+		if (!rc)
+			memcpy(local_buffer->raw_buffer, rtas_data_buf,
+			       RTAS_DATA_BUF_SIZE);
+		spin_unlock(&rtas_data_buf_lock);
+	} while (rtas_busy_delay(rc));
+
+	if (rc != 0) {
+		pr_err_once(
+			"%s %s Error calling get-system-parameter (0x%x)\n",
+			__FILE__, __func__, rc);
+	} else {
+		/* Force end of string */
+		len = be16_to_cpu(local_buffer->len);
+		if (len >= (RTAS_DATA_BUF_SIZE-2))
+			len = RTAS_DATA_BUF_SIZE-2;
+		local_buffer->name[len] = '\0';
+
+		seq_printf(m, "partition_name=%s\n", local_buffer->name);
+	}
+
+	kfree(local_buffer);
+}
+
+
 #define SPLPAR_CHARACTERISTICS_TOKEN 20
 #define SPLPAR_MAXLENGTH 1026*(sizeof(char))
 
@@ -496,6 +549,7 @@ static int pseries_lparcfg_data(struct seq_file *m, void *v)
 
 	if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
 		/* this call handles the ibm,get-system-parameter contents */
+		read_lpar_name(m);
 		parse_system_parameter_string(m);
 		parse_ppp_data(m);
 		parse_mpp_data(m);
-- 
2.34.1