Re: [Xen-devel] [PATCH 1/4] pvSCSI : Add white list to SCSI command emulation

[Steven Smith <steven.smith@xxxxxxxxxx>]

> +     bitmap[ERASE] = VSCSIIF_NEED_CMD_EXEC;
> +     pre_function[ERASE] = NULL;
> +     post_function[ERASE] = NULL;
> +
> +     bitmap[MODE_SENSE] = VSCSIIF_NEED_CMD_EXEC;
> +     pre_function[MODE_SENSE] = NULL;
> +     post_function[MODE_SENSE] = NULL;
> +
> +     bitmap[SEND_DIAGNOSTIC] = VSCSIIF_NEED_CMD_EXEC;
> +     pre_function[SEND_DIAGNOSTIC] = NULL;
> +     post_function[SEND_DIAGNOSTIC] = NULL;
Hmm, careful here.  If the DevOffL bit is set on a SEND DIAGNOSTIC
command then it can cause interference in other LUNs on the target,
which would be unfortunate if they're exposed to different VMs.

> +
> +     bitmap[READ_CAPACITY] = VSCSIIF_NEED_CMD_EXEC;
> +     pre_function[READ_CAPACITY] = NULL;
> +     post_function[READ_CAPACITY] = NULL;
> +
> +     bitmap[READ_10] = VSCSIIF_NEED_CMD_EXEC;
> +     pre_function[READ_10] = NULL;
> +     post_function[READ_10] = NULL;
> +
> +     bitmap[WRITE_10] = VSCSIIF_NEED_CMD_EXEC;
> +     pre_function[WRITE_10] = NULL;
> +     post_function[WRITE_10] = NULL;
Do you know what happens if the SCSI CDB is inconsistent with the
scatter list?  For instance, if the CDB says to read 16 sectors but
the frontend-supplied buffer is only big enough for 8, are we going to
end up DMAing over random memory?

Steven.

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