IB/core: Add support for extended query device caps

Add extensible query device capabilities verb to allow adding new features.
ib_uverbs_ex_query_device is added and copy_query_dev_fields is used to copy
capability fields to be used by both ib_uverbs_query_device and
ib_uverbs_ex_query_device.

Following the discussion about this patch [1], the code now validates
the command's comp_mask is zero, returning -EINVAL for unknown values,
in order to allow extending the verb in the future.

The verb also checks the user-space provided response buffer size and
only fills in capabilities that will fit in the buffer. In attempt to
follow the spirit of presentation [2] by Tzahi Oved that was presented
during OpenFabrics Alliance International Developer Workshop 2013, the
comp_mask bits will only describe which fields are valid.  Furthermore,
fields that can simply be cleared when they are not supported, do not
require a comp_mask bit at all.  The verb returns a response_length
field containing the actual number of bytes written by the kernel, so
that a newer version running on an older kernel can tell which fields
were actually returned.

[1] [PATCH v1 0/5] IB/core: extended query device caps cleanup for v3.19
    http://thread.gmane.org/gmane.linux.kernel.api/7889/

[2] https://www.openfabrics.org/images/docs/2013_Dev_Workshop/Tues_0423/2013_Workshop_Tues_0830_Tzahi_Oved-verbs_extensions_ofa_2013-tzahio.pdf

Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

3 files changed, 92 insertions, 41 deletions

diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index 643c08a025a5..b716b0815644 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -258,5 +258,6 @@ IB_UVERBS_DECLARE_CMD(close_xrcd);
 
 IB_UVERBS_DECLARE_EX_CMD(create_flow);
 IB_UVERBS_DECLARE_EX_CMD(destroy_flow);
+IB_UVERBS_DECLARE_EX_CMD(query_device);
 
 #endif /* UVERBS_H */
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index b7943ff16ed3..8f507538c42b 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -400,6 +400,52 @@ err:
         return ret;
 }
 
+static void copy_query_dev_fields(struct ib_uverbs_file *file,
+                                  struct ib_uverbs_query_device_resp *resp,
+                                  struct ib_device_attr *attr)
+{
+        resp->fw_ver            = attr->fw_ver;
+        resp->node_guid         = file->device->ib_dev->node_guid;
+        resp->sys_image_guid    = attr->sys_image_guid;
+        resp->max_mr_size       = attr->max_mr_size;
+        resp->page_size_cap     = attr->page_size_cap;
+        resp->vendor_id         = attr->vendor_id;
+        resp->vendor_part_id    = attr->vendor_part_id;
+        resp->hw_ver            = attr->hw_ver;
+        resp->max_qp            = attr->max_qp;
+        resp->max_qp_wr         = attr->max_qp_wr;
+        resp->device_cap_flags  = attr->device_cap_flags;
+        resp->max_sge           = attr->max_sge;
+        resp->max_sge_rd        = attr->max_sge_rd;
+        resp->max_cq            = attr->max_cq;
+        resp->max_cqe           = attr->max_cqe;
+        resp->max_mr            = attr->max_mr;
+        resp->max_pd            = attr->max_pd;
+        resp->max_qp_rd_atom    = attr->max_qp_rd_atom;
+        resp->max_ee_rd_atom    = attr->max_ee_rd_atom;
+        resp->max_res_rd_atom   = attr->max_res_rd_atom;
+        resp->max_qp_init_rd_atom       = attr->max_qp_init_rd_atom;
+        resp->max_ee_init_rd_atom       = attr->max_ee_init_rd_atom;
+        resp->atomic_cap                = attr->atomic_cap;
+        resp->max_ee                    = attr->max_ee;
+        resp->max_rdd                   = attr->max_rdd;
+        resp->max_mw                    = attr->max_mw;
+        resp->max_raw_ipv6_qp           = attr->max_raw_ipv6_qp;
+        resp->max_raw_ethy_qp           = attr->max_raw_ethy_qp;
+        resp->max_mcast_grp             = attr->max_mcast_grp;
+        resp->max_mcast_qp_attach       = attr->max_mcast_qp_attach;
+        resp->max_total_mcast_qp_attach = attr->max_total_mcast_qp_attach;
+        resp->max_ah                    = attr->max_ah;
+        resp->max_fmr                   = attr->max_fmr;
+        resp->max_map_per_fmr           = attr->max_map_per_fmr;
+        resp->max_srq                   = attr->max_srq;
+        resp->max_srq_wr                = attr->max_srq_wr;
+        resp->max_srq_sge               = attr->max_srq_sge;
+        resp->max_pkeys                 = attr->max_pkeys;
+        resp->local_ca_ack_delay        = attr->local_ca_ack_delay;
+        resp->phys_port_cnt             = file->device->ib_dev->phys_port_cnt;
+}
+
 ssize_t ib_uverbs_query_device(struct ib_uverbs_file *file,
                                const char __user *buf,
                                int in_len, int out_len)
@@ -420,47 +466,7 @@ ssize_t ib_uverbs_query_device(struct ib_uverbs_file *file,
                 return ret;
 
         memset(&resp, 0, sizeof resp);
-
-        resp.fw_ver                    = attr.fw_ver;
-        resp.node_guid                 = file->device->ib_dev->node_guid;
-        resp.sys_image_guid            = attr.sys_image_guid;
-        resp.max_mr_size               = attr.max_mr_size;
-        resp.page_size_cap             = attr.page_size_cap;
-        resp.vendor_id                 = attr.vendor_id;
-        resp.vendor_part_id            = attr.vendor_part_id;
-        resp.hw_ver                    = attr.hw_ver;
-        resp.max_qp                    = attr.max_qp;
-        resp.max_qp_wr                 = attr.max_qp_wr;
-        resp.device_cap_flags          = attr.device_cap_flags;
-        resp.max_sge                   = attr.max_sge;
-        resp.max_sge_rd                = attr.max_sge_rd;
-        resp.max_cq                    = attr.max_cq;
-        resp.max_cqe                   = attr.max_cqe;
-        resp.max_mr                    = attr.max_mr;
-        resp.max_pd                    = attr.max_pd;
-        resp.max_qp_rd_atom            = attr.max_qp_rd_atom;
-        resp.max_ee_rd_atom            = attr.max_ee_rd_atom;
-        resp.max_res_rd_atom           = attr.max_res_rd_atom;
-        resp.max_qp_init_rd_atom       = attr.max_qp_init_rd_atom;
-        resp.max_ee_init_rd_atom       = attr.max_ee_init_rd_atom;
-        resp.atomic_cap                = attr.atomic_cap;
-        resp.max_ee                    = attr.max_ee;
-        resp.max_rdd                   = attr.max_rdd;
-        resp.max_mw                    = attr.max_mw;
-        resp.max_raw_ipv6_qp           = attr.max_raw_ipv6_qp;
-        resp.max_raw_ethy_qp           = attr.max_raw_ethy_qp;
-        resp.max_mcast_grp             = attr.max_mcast_grp;
-        resp.max_mcast_qp_attach       = attr.max_mcast_qp_attach;
-        resp.max_total_mcast_qp_attach = attr.max_total_mcast_qp_attach;
-        resp.max_ah                    = attr.max_ah;
-        resp.max_fmr                   = attr.max_fmr;
-        resp.max_map_per_fmr           = attr.max_map_per_fmr;
-        resp.max_srq                   = attr.max_srq;
-        resp.max_srq_wr                = attr.max_srq_wr;
-        resp.max_srq_sge               = attr.max_srq_sge;
-        resp.max_pkeys                 = attr.max_pkeys;
-        resp.local_ca_ack_delay        = attr.local_ca_ack_delay;
-        resp.phys_port_cnt             = file->device->ib_dev->phys_port_cnt;
+        copy_query_dev_fields(file, &resp, &attr);
 
         if (copy_to_user((void __user *) (unsigned long) cmd.response,
                          &resp, sizeof resp))
@@ -3287,3 +3293,46 @@ ssize_t ib_uverbs_destroy_srq(struct ib_uverbs_file *file,
 
         return ret ? ret : in_len;
 }
+
+int ib_uverbs_ex_query_device(struct ib_uverbs_file *file,
+                              struct ib_udata *ucore,
+                              struct ib_udata *uhw)
+{
+        struct ib_uverbs_ex_query_device_resp resp;
+        struct ib_uverbs_ex_query_device  cmd;
+        struct ib_device_attr attr;
+        struct ib_device *device;
+        int err;
+
+        device = file->device->ib_dev;
+        if (ucore->inlen < sizeof(cmd))
+                return -EINVAL;
+
+        err = ib_copy_from_udata(&cmd, ucore, sizeof(cmd));
+        if (err)
+                return err;
+
+        if (cmd.comp_mask)
+                return -EINVAL;
+
+        if (cmd.reserved)
+                return -EINVAL;
+
+        resp.response_length = sizeof(resp);
+
+        if (ucore->outlen < resp.response_length)
+                return -ENOSPC;
+
+        err = device->query_device(device, &attr);
+        if (err)
+                return err;
+
+        copy_query_dev_fields(file, &resp.base, &attr);
+        resp.comp_mask = 0;
+
+        err = ib_copy_to_udata(ucore, &resp, resp.response_length);
+        if (err)
+                return err;
+
+        return 0;
+}
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 5db1a8cc388d..259dcc7779f5 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -123,6 +123,7 @@ static int (*uverbs_ex_cmd_table[])(struct ib_uverbs_file *file,
                                     struct ib_udata *uhw) = {
         [IB_USER_VERBS_EX_CMD_CREATE_FLOW]      = ib_uverbs_ex_create_flow,
         [IB_USER_VERBS_EX_CMD_DESTROY_FLOW]     = ib_uverbs_ex_destroy_flow,
+        [IB_USER_VERBS_EX_CMD_QUERY_DEVICE]     = ib_uverbs_ex_query_device,
 };
 
 static void ib_uverbs_add_one(struct ib_device *device);