[PATCH v2] arm/scmi: fix base agent discover response

From: Vincent Guittot
Date: Wed Nov 17 2021 - 03:19:11 EST


According to scmi specification, the response of the discover agent request
is made of:
- int32 status
- uint32 agent_id
- uint8 name[16]

but the current implementation doesn't take into account the agent_id field
and only allocates a rx buffer of SCMI_MAX_STR_SIZE length

Allocate the correct length for rx buffer and copy the name from the
correct offset in the response.

While no error were returned until v5.15, v5.16-rc1 fails with virtio_scmi
transport channel:

[ 1.093253] arm-scmi firmware:scmi0: SCMI Notifications - Core Enabled.
[ 1.114776] arm-scmi firmware:scmi0: SCMI Protocol v2.0 'Linaro:PMWG' Firmware version 0x2090000
[ 1.117544] scmi-virtio virtio0: tx:used len 28 is larger than in buflen 24

Fixes: b6f20ff8bd94 ("firmware: arm_scmi: add common infrastructure and support for base protocol")
Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Reviewed-by: Cristian Marussi <cristian.marussi@xxxxxxx>
Tested-by: Cristian Marussi <cristian.marussi@xxxxxxx>
---

Change since v1:
- Added Fixes tag
- Added Tested and Review tag

drivers/firmware/arm_scmi/base.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c
index de416f9e7921..f5219334fd3a 100644
--- a/drivers/firmware/arm_scmi/base.c
+++ b/drivers/firmware/arm_scmi/base.c
@@ -34,6 +34,12 @@ struct scmi_msg_resp_base_attributes {
__le16 reserved;
};

+struct scmi_msg_resp_base_discover_agent {
+ __le32 agent_id;
+ u8 name[SCMI_MAX_STR_SIZE];
+};
+
+
struct scmi_msg_base_error_notify {
__le32 event_control;
#define BASE_TP_NOTIFY_ALL BIT(0)
@@ -225,18 +231,21 @@ static int scmi_base_discover_agent_get(const struct scmi_protocol_handle *ph,
int id, char *name)
{
int ret;
+ struct scmi_msg_resp_base_discover_agent *agent_info;
struct scmi_xfer *t;

ret = ph->xops->xfer_get_init(ph, BASE_DISCOVER_AGENT,
- sizeof(__le32), SCMI_MAX_STR_SIZE, &t);
+ sizeof(__le32), sizeof(*agent_info), &t);
if (ret)
return ret;

put_unaligned_le32(id, t->tx.buf);

ret = ph->xops->do_xfer(ph, t);
- if (!ret)
- strlcpy(name, t->rx.buf, SCMI_MAX_STR_SIZE);
+ if (!ret) {
+ agent_info = t->rx.buf;
+ strlcpy(name, agent_info->name, SCMI_MAX_STR_SIZE);
+ }

ph->xops->xfer_put(ph, t);

--
2.17.1