From 2b2bfc8aa519f696087475ed8e8c61850c673272 Mon Sep 17 00:00:00 2001 From: Kiwoong Kim Date: Tue, 19 Jan 2021 12:33:41 +0900 Subject: [PATCH] scsi: ufs: Introduce a quirk to allow only page-aligned sg entries Some SoCs require a single scatterlist entry for smaller than page size, i.e. 4KB. When dispatching commands with more than one scatterlist entry under 4KB in size the following behavior is observed: A command to read a block range is dispatched with two scatterlist entries that are named AAA and BBB. After dispatching, the host builds two PRDT entries and during transmission, device sends just one DATA IN because device doesn't care about host DMA. The host then transfers the combined amount of data from start address of the area named AAA. As a consequence, the area that follows AAA in memory would be corrupted. |<------------->| +-------+------------ +-------+ + AAA + (corrupted) ... + BBB + +-------+------------ +-------+ To avoid this we need to enforce page size alignment for sg entries. Link: https://lore.kernel.org/r/56dddef94f60bd9466fd77e69f64bbbd657ed2a1.1611026909.git.kwmad.kim@samsung.com Signed-off-by: Kiwoong Kim Signed-off-by: Martin K. Petersen --- drivers/scsi/ufs/ufshcd.c | 2 ++ drivers/scsi/ufs/ufshcd.h | 4 ++++ 2 files changed, 6 insertions(+) diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index c22e751bb030..a4631caabf30 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -4852,6 +4852,8 @@ static int ufshcd_slave_configure(struct scsi_device *sdev) struct request_queue *q = sdev->request_queue; blk_queue_update_dma_pad(q, PRDT_DATA_BYTE_COUNT_PAD - 1); + if (hba->quirks & UFSHCD_QUIRK_ALIGN_SG_WITH_PAGE_SIZE) + blk_queue_update_dma_alignment(q, PAGE_SIZE - 1); if (ufshcd_is_rpm_autosuspend_allowed(hba)) sdev->rpm_autosuspend = 1; diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h index 5bbe4715d4e9..a5c6084c8615 100644 --- a/drivers/scsi/ufs/ufshcd.h +++ b/drivers/scsi/ufs/ufshcd.h @@ -559,6 +559,10 @@ enum ufshcd_quirks { */ UFSHCD_QUIRK_SKIP_DEF_UNIPRO_TIMEOUT_SETTING = 1 << 13, + /* + * This quirk allows only sg entries aligned with page size. + */ + UFSHCD_QUIRK_ALIGN_SG_WITH_PAGE_SIZE = 1 << 13, }; enum ufshcd_caps {