From: John Garry john.garry@huawei.com
[ Upstream commit fce54ed027577517df1e74b7d54dc2b1bd536887 ]
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@hu...
Link: https://lore.kernel.org/r/1655988119-223714-1-git-send-email-john.garry@huaw... Signed-off-by: John Garry john.garry@huawei.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c index cd41dc061d87..dfe7e6370d84 100644 --- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c +++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c @@ -2738,6 +2738,7 @@ 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; @@ -2755,6 +2756,12 @@ 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; }