On 2/24/2014 9:01 AM, Nicholas A. Bellinger wrote:
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-rc2Series applied to target-pending/rdma-dif, minus the missing upstream check in patch #5. Thanks Sagi! --nab
Thanks Nic. -- 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
