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Enhances the t4_dev_status_page to pass the qid start and size
attributes from iw_cxgb4 to libcxgb4.
Bump the ABI Version to 3 -> To allow libcxgb4 to detect old drivers and
revert to the old way of computing the qid ranges.
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
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The i386 ABI disagrees with most other ABIs regarding alignment of
data types larger than 4 bytes: on most ABIs a padding must be added
at end of the structures, while it is not required on i386.
So for most ABI struct c4iw_alloc_ucontext_resp gets implicitly padded
to be aligned on a 8 bytes multiple, while for i386, such padding is
not added.
The tool pahole can be used to find such implicit padding:
$ pahole --anon_include \
--nested_anon_include \
--recursive \
--class_name c4iw_alloc_ucontext_resp \
drivers/infiniband/hw/cxgb4/iw_cxgb4.o
Then, structure layout can be compared between i386 and x86_64:
+++ obj-i386/drivers/infiniband/hw/cxgb4/iw_cxgb4.o.pahole.txt 2014-03-28 11:43:05.547432195 +0100
--- obj-x86_64/drivers/infiniband/hw/cxgb4/iw_cxgb4.o.pahole.txt 2014-03-28 10:55:10.990133017 +0100
@@ -2,9 +2,8 @@ struct c4iw_alloc_ucontext_resp {
__u64 status_page_key; /* 0 8 */
__u32 status_page_size; /* 8 4 */
- /* size: 12, cachelines: 1, members: 2 */
- /* last cacheline: 12 bytes */
+ /* size: 16, cachelines: 1, members: 2 */
+ /* padding: 4 */
+ /* last cacheline: 16 bytes */
};
This ABI disagreement will make an x86_64 kernel try to write past the
buffer provided by an i386 binary.
When boundary check will be implemented, the x86_64 kernel will refuse
to write past the i386 userspace provided buffer and the uverbs will
fail.
If the structure is on a page boundary and the next page is not
mapped, ib_copy_to_udata() will fail and the uverb will fail.
Additionally, as reported by Dan Carpenter, without the implicit
padding being properly cleared, an information leak would take place
in most architectures.
This patch adds an explicit padding to struct c4iw_alloc_ucontext_resp,
and, like 92b0ca7cb149 ("IB/mlx5: Fix stack info leak in
mlx5_ib_alloc_ucontext()"), makes function c4iw_alloc_ucontext()
not writting this padding field to userspace. This way, x86_64 kernel
will be able to write struct c4iw_alloc_ucontext_resp as expected by
unpatched and patched i386 libcxgb4.
Link: http://marc.info/?i=cover.1399309513.git.ydroneaud@opteya.com
Link: http://marc.info/?i=1395848977.3297.15.camel@localhost.localdomain
Link: http://marc.info/?i=20140328082428.GH25192@mwanda
Cc: <stable@vger.kernel.org>
Fixes: 05eb23893c2c ("cxgb4/iw_cxgb4: Doorbell Drop Avoidance Bug Fixes")
Reported-by: Yann Droneaud <ydroneaud@opteya.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
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The i386 ABI disagrees with most other ABIs regarding alignment of
data types larger than 4 bytes: on most ABIs a padding must be added
at end of the structures, while it is not required on i386.
So for most ABI struct c4iw_create_cq_resp gets implicitly padded
to be aligned on a 8 bytes multiple, while for i386, such padding
is not added.
The tool pahole can be used to find such implicit padding:
$ pahole --anon_include \
--nested_anon_include \
--recursive \
--class_name c4iw_create_cq_resp \
drivers/infiniband/hw/cxgb4/iw_cxgb4.o
Then, structure layout can be compared between i386 and x86_64:
+++ obj-i386/drivers/infiniband/hw/cxgb4/iw_cxgb4.o.pahole.txt 2014-03-28 11:43:05.547432195 +0100
--- obj-x86_64/drivers/infiniband/hw/cxgb4/iw_cxgb4.o.pahole.txt 2014-03-28 10:55:10.990133017 +0100
@@ -14,9 +13,8 @@ struct c4iw_create_cq_resp {
__u32 size; /* 28 4 */
__u32 qid_mask; /* 32 4 */
- /* size: 36, cachelines: 1, members: 6 */
- /* last cacheline: 36 bytes */
+ /* size: 40, cachelines: 1, members: 6 */
+ /* padding: 4 */
+ /* last cacheline: 40 bytes */
};
This ABI disagreement will make an x86_64 kernel try to write past the
buffer provided by an i386 binary.
When boundary check will be implemented, the x86_64 kernel will refuse
to write past the i386 userspace provided buffer and the uverbs will
fail.
If the structure is on a page boundary and the next page is not
mapped, ib_copy_to_udata() will fail and the uverb will fail.
This patch adds an explicit padding at end of structure
c4iw_create_cq_resp, and, like 92b0ca7cb149 ("IB/mlx5: Fix stack info
leak in mlx5_ib_alloc_ucontext()"), makes function c4iw_create_cq()
not writting this padding field to userspace. This way, x86_64 kernel
will be able to write struct c4iw_create_cq_resp as expected by
unpatched and patched i386 libcxgb4.
Link: http://marc.info/?i=cover.1399309513.git.ydroneaud@opteya.com
Cc: <stable@vger.kernel.org>
Fixes: cfdda9d764362 ("RDMA/cxgb4: Add driver for Chelsio T4 RNIC")
Fixes: e24a72a3302a6 ("RDMA/cxgb4: Fix four byte info leak in c4iw_create_cq()")
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
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The current logic suffers from a slow response time to disable user DB
usage, and also fails to avoid DB FIFO drops under heavy load. This commit
fixes these deficiencies and makes the avoidance logic more optimal.
This is done by more efficiently notifying the ULDs of potential DB
problems, and implements a smoother flow control algorithm in iw_cxgb4,
which is the ULD that puts the most load on the DB fifo.
Design:
cxgb4:
Direct ULD callback from the DB FULL/DROP interrupt handler. This allows
the ULD to stop doing user DB writes as quickly as possible.
While user DB usage is disabled, the LLD will accumulate DB write events
for its queues. Then once DB usage is reenabled, a single DB write is
done for each queue with its accumulated write count. This reduces the
load put on the DB fifo when reenabling.
iw_cxgb4:
Instead of marking each qp to indicate DB writes are disabled, we create
a device-global status page that each user process maps. This allows
iw_cxgb4 to only set this single bit to disable all DB writes for all
user QPs vs traversing the idr of all the active QPs. If the libcxgb4
doesn't support this, then we fall back to the old approach of marking
each QP. Thus we allow the new driver to work with an older libcxgb4.
When the LLD upcalls iw_cxgb4 indicating DB FULL, we disable all DB writes
via the status page and transition the DB state to STOPPED. As user
processes see that DB writes are disabled, they call into iw_cxgb4
to submit their DB write events. Since the DB state is in STOPPED,
the QP trying to write gets enqueued on a new DB "flow control" list.
As subsequent DB writes are submitted for this flow controlled QP, the
amount of writes are accumulated for each QP on the flow control list.
So all the user QPs that are actively ringing the DB get put on this
list and the number of writes they request are accumulated.
When the LLD upcalls iw_cxgb4 indicating DB EMPTY, which is in a workq
context, we change the DB state to FLOW_CONTROL, and begin resuming all
the QPs that are on the flow control list. This logic runs on until
the flow control list is empty or we exit FLOW_CONTROL mode (due to
a DB DROP upcall, for example). QPs are removed from this list, and
their accumulated DB write counts written to the DB FIFO. Sets of QPs,
called chunks in the code, are removed at one time. The chunk size is 64.
So 64 QPs are resumed at a time, and before the next chunk is resumed, the
logic waits (blocks) for the DB FIFO to drain. This prevents resuming to
quickly and overflowing the FIFO. Once the flow control list is empty,
the db state transitions back to NORMAL and user QPs are again allowed
to write directly to the user DB register.
The algorithm is designed such that if the DB write load is high enough,
then all the DB writes get submitted by the kernel using this flow
controlled approach to avoid DB drops. As the load lightens though, we
resume to normal DB writes directly by user applications.
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Get FULL/EMPTY/DROP events from LLD. On FULL event, disable normal
user mode DB rings.
Add modify_qp semantics to allow user processes to call into the
kernel to ring doobells without overflowing.
Add DB Full/Empty/Drop stats.
Mark queues when created indicating the doorbell state.
If we're in the middle of db overflow avoidance, then newly created
queues should start out in this mode.
Bump the C4IW_UVERBS_ABI_VERSION to 2 so the user mode library can
know if the driver supports the kernel mode db ringing.
Signed-off-by: Vipul Pandya <vipul@chelsio.com>
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
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T4 support on-chip SQs to reduce latency. This patch adds support for
this in iw_cxgb4:
- Manage ocqp memory like other adapter mem resources.
- Allocate user mode SQs from ocqp mem if available.
- Map ocqp mem to user process using write combining.
- Map PCIE_MA_SYNC reg to user process.
Bump uverbs ABI.
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
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Add an RDMA/iWARP driver for Chelsio T4 Ethernet adapters.
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
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Hariprasad S
Yann Droneaud
Steve Wise
Vipul Pandya