On Sun, 2014-02-23 at 14:19 +0200, Sagi Grimberg wrote: > This patchset Introduces Verbs level support for signature handover feature. > Siganture is intended to implement end-to-end data integrity on a transactional > basis in a completely offloaded manner. > > There are several end-to-end data integrity methods used today in various > applications and/or upper layer protocols such as T10-DIF defined by SCSI > specifications (SBC), CRC32, XOR8 and more. This patchset adds verbs support > only for T10-DIF. The proposed framework allows adding more signature methods > in the future. > > In T10-DIF, when a series of 512-byte data blocks are transferred, each block > is followed by an 8-byte guard (note that other protection intervals may be used > other then 512-bytes). The guard consists of CRC that protects the integrity of > the data in the block, and tag that protects against mis-directed IOs and a free > tag for application use. > > Data can be protected when transferred over the wire, but can also be protected > in the memory of the sender/receiver. This allows true end- to-end protection > against bits flipping either over the wire, through gateways, in memory, over PCI, etc. > > While T10-DIF clearly defines that over the wire protection guards are interleaved > into the data stream (each 512-Byte block followed by 8-byte guard), when in memory, > the protection guards may reside in a buffer separated from the data. Depending on the > application, it is usually easier to handle the data when it is contiguous. > In this case the data buffer will be of size 512xN and the protection buffer will > be of size 8xN (where N is the number of blocks in the transaction). > > There are 3 kinds of signature handover operation: > 1. Take unprotected data (from wire or memory) and ADD protection > guards. > 2. Take protetected data (from wire or memory), validate the data > integrity against the protection guards and STRIP the protection > guards. > 3. Take protected data (from wire or memory), validate the data > integrity against the protection guards and PASS the data with > the guards as-is. > > This translates to defining to the HCA how/if data protection exists in memory domain, > and how/if data protection exists is wire domain. > > The way that data integrity is performed is by using a new kind of memory > region: signature-enabled MR, and a new kind of work request: REG_SIG_MR. > The REG_SIG_MR WR operates on the signature-enabled MR, and defines all the > needed information for the signature handover (data buffer, protection buffer > if needed and signature attributes). The result is an MR that can be used for > data transfer as usual, that will also add/validate/strip/pass protection guards. > > When the data transfer is successfully completed, it does not mean that there are > no integrity errors. The user must afterwards check the signature status of the > handover operation using a new light-weight verb. > > This feature shall be used in storage upper layer protocols iSER/SRP implementing > end-to-end data integrity T10-DIF. Following this patchset, ib_iser/ib_isert > will use these verbs for T10-PI offload support. > > Patchset summary: > - Intoduce verbs for create/destroy memory regions supporting signature. > - Introduce IB core signature verbs API. > - Implement mr create/destroy verbs in mlx5 driver. > - Preperation patches for signature support in mlx5 driver. > - Implement signature handover work request in mlx5 driver. > - Implement signature error collection and handling in mlx5 driver. > > Changes from v4: > - Update to for-next 3.14-rc2 Series applied to target-pending/rdma-dif, minus the missing upstream check in patch #5. Thanks Sagi! --nab -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
