nvme: Handle zero Maximum Data Transfer Size (MDTS)
Maximum Data Transfer Size (MDTS) field indicates the maximum data transfer size between the host and the controller. The host should not submit a command that exceeds this transfer size. The value is in units of the minimum memory page size and is reported as a power of two (2^n). The spec also says: a value of 0h indicates no restrictions on transfer size. On the real NVMe card this is normally not 0 due to hardware restrictions, but with QEMU emulated NVMe device it reports as 0. In nvme_blk_read/write() below we have the following algorithm for maximum number of logic blocks per transfer: u16 lbas = 1 << (dev->max_transfer_shift - ns->lba_shift); dev->max_transfer_shift being 0 will for sure cause lbas to overflow. Let's use 20. With this fix, the NVMe driver works on QEMU emulated NVMe device. Signed-off-by: NBin Meng <bmeng.cn@gmail.com> Reviewed-by: NTom Rini <trini@konsulko.com>
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