[PATCH v4 11/18] nvme: Add pr_ops read_keys support

[Mike Christie]

This patch adds support for the pr_ops read_keys callout by calling the
NVMe Reservation Report helper, then parsing that info to get the
controller's registered keys. Because the callout is only used in the
kernel where the callers, like LIO, do not know about controller/host IDs,
the callout just returns the registered keys which is required by the SCSI
PR in READ KEYS command.

Signed-off-by: Mike Christie <michael.christie at oracle.com>
---
 drivers/nvme/host/pr.c | 65 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/nvme.h   |  4 +++
 2 files changed, 69 insertions(+)

diff --git a/drivers/nvme/host/pr.c b/drivers/nvme/host/pr.c
index 7a1d93da4970..ac6b9008e7e1 100644
--- a/drivers/nvme/host/pr.c
+++ b/drivers/nvme/host/pr.c
@@ -151,10 +151,75 @@ static int nvme_pr_release(struct block_device *bdev, u64 key, enum pr_type type
 	return nvme_pr_command(bdev, cdw10, key, 0, nvme_cmd_resv_release);
 }
 
+static int nvme_pr_resv_report(struct block_device *bdev, void *data,
+		u32 data_len, bool *eds)
+{
+	struct nvme_command c = { };
+	int ret;
+
+	c.common.opcode = nvme_cmd_resv_report;
+	c.common.cdw10 = cpu_to_le32(nvme_bytes_to_numd(data_len));
+	c.common.cdw11 = NVME_EXTENDED_DATA_STRUCT;
+	*eds = true;
+
+retry:
+	ret = nvme_send_pr_command(bdev, &c, data, data_len);
+	if (ret == NVME_SC_HOST_ID_INCONSIST &&
+	    c.common.cdw11 == NVME_EXTENDED_DATA_STRUCT) {
+		c.common.cdw11 = 0;
+		*eds = false;
+		goto retry;
+	}
+
+	if (ret < 0)
+		return ret;
+
+	return nvme_sc_to_pr_err(ret);
+}
+
+static int nvme_pr_read_keys(struct block_device *bdev,
+		struct pr_keys *keys_info)
+{
+	u32 rs_len, num_keys = keys_info->num_keys;
+	struct nvme_reservation_status *rs;
+	int ret, i;
+	bool eds;
+
+	/*
+	 * Assume we are using 128-bit host IDs and allocate a buffer large
+	 * enough to get enough keys to fill the return keys buffer.
+	 */
+	rs_len = sizeof(*rs) +
+			num_keys * sizeof(struct nvme_registered_ctrl_ext);
+	rs = kzalloc(rs_len, GFP_KERNEL);
+	if (!rs)
+		return -ENOMEM;
+
+	ret = nvme_pr_resv_report(bdev, rs, rs_len, &eds);
+	if (ret)
+		goto free_rs;
+
+	keys_info->generation = le32_to_cpu(rs->gen);
+	keys_info->num_keys = get_unaligned_le16(&rs->regctl);
+
+	num_keys = min(num_keys, keys_info->num_keys);
+	for (i = 0; i < num_keys; i++) {
+		if (eds)
+			keys_info->keys[i] = le64_to_cpu(rs->regctl_eds[i].rkey);
+		else
+			keys_info->keys[i] = le64_to_cpu(rs->regctl_ds[i].rkey);
+	}
+
+free_rs:
+	kfree(rs);
+	return ret;
+}
+
 const struct pr_ops nvme_pr_ops = {
 	.pr_register	= nvme_pr_register,
 	.pr_reserve	= nvme_pr_reserve,
 	.pr_release	= nvme_pr_release,
 	.pr_preempt	= nvme_pr_preempt,
 	.pr_clear	= nvme_pr_clear,
+	.pr_read_keys	= nvme_pr_read_keys,
 };
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index c8c504926462..50fc596ec888 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -759,6 +759,10 @@ enum {
 	NVME_LBART_ATTRIB_HIDE	= 1 << 1,
 };
 
+enum nvme_eds {
+	NVME_EXTENDED_DATA_STRUCT	= 0x1,
+};
+
 struct nvme_registered_ctrl {
 	__le16	cntlid;
 	__u8	rcsts;
-- 
2.25.1