Re: [PATCH 02/29] ibmvfc: add NVMe/FC protocol interface definitions

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Unconditional size expansion of `struct ibmvfc_implicit_logout` breaks backwards compatibility with older VIOS versions.
--

commit c4f31afebbe28cbb64ba03689b7e7ed327cb6d9e
Author: Tyrel Datwyler <tyreld@linux.ibm.com>

ibmvfc: add NVMe/FC protocol interface definitions

This commit adds the protocol definitions for client-VIOS interface updates
needed to support NVMe/FC over the ibmvfc NPIV transport. It extends the
ibmvfc interface with NVMe/FC-specific capabilities, queue definitions,
and command layout support.

> diff --git a/drivers/scsi/ibmvscsi/ibmvfc.h b/drivers/scsi/ibmvscsi/ibmvfc.h
> index 0e259e9d2e9bb..f8a2bf92da410 100644
> --- a/drivers/scsi/ibmvscsi/ibmvfc.h
> +++ b/drivers/scsi/ibmvscsi/ibmvfc.h

[ ... ]

> @@ -377,20 +419,27 @@ struct ibmvfc_query_tgt {
>  struct ibmvfc_implicit_logout {
>  	struct ibmvfc_mad_common common;
>  	__be64 old_scsi_id;
> -	__be64 reserved[2];
> +	__be64 reserved[8];
> +	__be64 target_wwpn;
>  } __packed __aligned(8);

[Severity: High]
Will this unconditional size expansion break backwards compatibility with older
Virtual I/O Server (VIOS) firmware?

Since the driver calculates the MAD length dynamically using sizeof():

drivers/scsi/ibmvscsi/ibmvfc.c:__ibmvfc_tgt_get_implicit_logout_evt() {
    ...
    mad->common.length = cpu_to_be16(sizeof(*mad));
    ...
}

This changes the length sent for version 1 IBMVFC_IMPLICIT_LOGOUT operations
from 40 bytes to 96 bytes. Could older VIOS versions that strictly validate
MAD lengths against the version 1 specification reject this payload, breaking
target teardown and error recovery?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260623013035.3436640-1-tyreld@linux.ibm.com?part=2