[PATCH v4 16/18] nvmet: Implement arbitration feature support

Damien Le Moal
2024-12-12T11:35:34Z

NVMe base specification v2.1 mandates support for the arbitration
feature (NVME_FEAT_ARBITRATION). Introduce the data structure
struct nvmet_feat_arbitration to define the high, medium and low
priority weight fields and the arbitration burst field of this feature
and implement the functions nvmet_get_feat_arbitration() and
nvmet_set_feat_arbitration() functions to get and set these fields.

Since there is no generic way to implement support for the arbitration
feature, these functions respectively use the controller get_feature()
and set_feature() operations to process the feature with the help of
the controller driver. If the controller driver does not implement these
operations and a get feature command or a set feature command for this
feature is received, the command is failed with an invalid field error.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Rick Wertenbroek <rick.wertenbroek@gmail.com>
---
drivers/nvme/target/admin-cmd.c | 51 +++++++++++++++++++++++++++++++--
drivers/nvme/target/nvmet.h | 7 +++++
2 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
index 8b8ec33330b2..3ddd8e44e148 100644
--- a/drivers/nvme/target/admin-cmd.c
+++ b/drivers/nvme/target/admin-cmd.c
@@ -1324,6 +1324,25 @@ static u16 nvmet_set_feat_irq_config(struct nvmet_req *req)
return ctrl->ops->set_feature(ctrl, NVME_FEAT_IRQ_CONFIG, &irqcfg);
}

+static u16 nvmet_set_feat_arbitration(struct nvmet_req *req)
+{
+ struct nvmet_ctrl *ctrl = req->sq->ctrl;
+ u32 cdw11 = le32_to_cpu(req->cmd->common.cdw11);
+ struct nvmet_feat_arbitration arb = {
+ .hpw = (cdw11 >> 24) & 0xff,
+ .mpw = (cdw11 >> 16) & 0xff,
+ .lpw = (cdw11 >> 8) & 0xff,
+ .ab = cdw11 & 0x3,
+ };
+
+ if (!ctrl->ops->set_feature) {
+ req->error_loc = offsetof(struct nvme_common_command, cdw10);
+ return NVME_SC_INVALID_FIELD | NVME_STATUS_DNR;
+ }
+
+ return ctrl->ops->set_feature(ctrl, NVME_FEAT_ARBITRATION, &arb);
+}
+
void nvmet_execute_set_features(struct nvmet_req *req)
{
struct nvmet_subsys *subsys = nvmet_req_subsys(req);
@@ -1337,6 +1356,9 @@ void nvmet_execute_set_features(struct nvmet_req *req)
return;

switch (cdw10 & 0xff) {
+ case NVME_FEAT_ARBITRATION:
+ status = nvmet_set_feat_arbitration(req);
+ break;
case NVME_FEAT_NUM_QUEUES:
ncqr = (cdw11 >> 16) & 0xffff;
nsqr = cdw11 & 0xffff;
@@ -1446,6 +1468,30 @@ static u16 nvmet_get_feat_irq_config(struct nvmet_req *req)
return NVME_SC_SUCCESS;
}

+static u16 nvmet_get_feat_arbitration(struct nvmet_req *req)
+{
+ struct nvmet_ctrl *ctrl = req->sq->ctrl;
+ struct nvmet_feat_arbitration arb = { };
+ u16 status;
+
+ if (!ctrl->ops->get_feature) {
+ req->error_loc = offsetof(struct nvme_common_command, cdw10);
+ return NVME_SC_INVALID_FIELD | NVME_STATUS_DNR;
+ }
+
+ status = ctrl->ops->get_feature(ctrl, NVME_FEAT_ARBITRATION, &arb);
+ if (status != NVME_SC_SUCCESS)
+ return status;
+
+ nvmet_set_result(req,
+ ((u32)arb.hpw << 24) |
+ ((u32)arb.mpw << 16) |
+ ((u32)arb.lpw << 8) |
+ (arb.ab & 0x3));
+
+ return NVME_SC_SUCCESS;
+}
+
void nvmet_get_feat_kato(struct nvmet_req *req)
{
nvmet_set_result(req, req->sq->ctrl->kato * 1000);
@@ -1472,8 +1518,6 @@ void nvmet_execute_get_features(struct nvmet_req *req)
* need to come up with some fake values for these.
*/
#if 0
- case NVME_FEAT_ARBITRATION:
- break;
case NVME_FEAT_POWER_MGMT:
break;
case NVME_FEAT_TEMP_THRESH:
@@ -1483,6 +1527,9 @@ void nvmet_execute_get_features(struct nvmet_req *req)
case NVME_FEAT_WRITE_ATOMIC:
break;
#endif
+ case NVME_FEAT_ARBITRATION:
+ status = nvmet_get_feat_arbitration(req);
+ break;
case NVME_FEAT_IRQ_COALESCE:
status = nvmet_get_feat_irq_coalesce(req);
break;
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 999a4ebf597e..f4df458df9db 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -921,4 +921,11 @@ struct nvmet_feat_irq_config {
bool cd;
};

+struct nvmet_feat_arbitration {
+ u8 hpw;
+ u8 mpw;
+ u8 lpw;
+ u8 ab;
+};
+
#endif /* _NVMET_H */
--
2.47.1