scsi: hisi_sas: Limit max hw sectors for v3 HW

If the controller is behind an IOMMU then the IOMMU IOVA caching range can
affect performance, as discussed in [0].

Limit the max HW sectors to not exceed this limit. We need to hardcode the
value until a proper DMA mapping API is available.

[0] https://lore.kernel.org/linux-iommu/20210129092120.1482-1-thunder.leizhen@huawei.com/

Link: https://lore.kernel.org/r/1655988119-223714-1-git-send-email-john.garry@huawei.com
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
John Garry 2022-06-23 20:41:59 +08:00 committed by Martin K. Petersen
parent aeaadcde1a
commit fce54ed027

View File

@ -2782,6 +2782,7 @@ static int slave_configure_v3_hw(struct scsi_device *sdev)
struct hisi_hba *hisi_hba = shost_priv(shost);
struct device *dev = hisi_hba->dev;
int ret = sas_slave_configure(sdev);
unsigned int max_sectors;
if (ret)
return ret;
@ -2799,6 +2800,12 @@ static int slave_configure_v3_hw(struct scsi_device *sdev)
}
}
/* Set according to IOMMU IOVA caching limit */
max_sectors = min_t(size_t, queue_max_hw_sectors(sdev->request_queue),
(PAGE_SIZE * 32) >> SECTOR_SHIFT);
blk_queue_max_hw_sectors(sdev->request_queue, max_sectors);
return 0;
}