linux-kernel - [PATCH] scsi: ufs: core: Limit DMA alignment check

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Message-ID: <20230201034917.1902330-1-quic_bjorande@quicinc.com>
Date:   Tue, 31 Jan 2023 19:49:17 -0800
From:   Bjorn Andersson <quic_bjorande@...cinc.com>
To:     Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        Bart Van Assche <bvanassche@....org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Asutosh Das <quic_asutoshd@...cinc.com>
CC:     Bean Huo <beanhuo@...ron.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Jinyoung Choi <j-young.choi@...sung.com>,
        <linux-scsi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <mani@...nel.org>
Subject: [PATCH] scsi: ufs: core: Limit DMA alignment check

The three DMA memory regions allocated for the host memory space is
documented to require alignment of 128, 1024 and 1024 respectively, but
the returned address is checked for PAGE_SIZE alignment.

In the case these allocations are serviced by e.g. the Arm SMMU, the
size and alignment will be determined by its supported page sizes. In
most cases SZ_4K and a few larger sizes are available.

In the typical configuration this does not cause problems, but in the
event that the system PAGE_SIZE is increased beyond 4k, it's no longer
reasonable to expect that the allocation will be PAGE_SIZE aligned.

Limit the DMA alignment check to the actual alignment requirements
written in the comments in the code, to avoid the UFS core refusing to
initialize with such configuration.

Signed-off-by: Bjorn Andersson <quic_bjorande@...cinc.com>
---
 drivers/ufs/core/ufshcd.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index ec732e4bbbf4..d7f3f1ba9d12 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -3724,12 +3724,9 @@ static int ufshcd_memory_alloc(struct ufs_hba *hba)
 
 	/*
 	 * UFSHCI requires UTP command descriptor to be 128 byte aligned.
-	 * make sure hba->ucdl_dma_addr is aligned to PAGE_SIZE
-	 * if hba->ucdl_dma_addr is aligned to PAGE_SIZE, then it will
-	 * be aligned to 128 bytes as well
 	 */
 	if (!hba->ucdl_base_addr ||
-	    WARN_ON(hba->ucdl_dma_addr & (PAGE_SIZE - 1))) {
+	    WARN_ON(hba->ucdl_dma_addr & (128 - 1))) {
 		dev_err(hba->dev,
 			"Command Descriptor Memory allocation failed\n");
 		goto out;
@@ -3745,7 +3742,7 @@ static int ufshcd_memory_alloc(struct ufs_hba *hba)
 						   &hba->utrdl_dma_addr,
 						   GFP_KERNEL);
 	if (!hba->utrdl_base_addr ||
-	    WARN_ON(hba->utrdl_dma_addr & (PAGE_SIZE - 1))) {
+	    WARN_ON(hba->utrdl_dma_addr & (1024 - 1))) {
 		dev_err(hba->dev,
 			"Transfer Descriptor Memory allocation failed\n");
 		goto out;
@@ -3769,7 +3766,7 @@ static int ufshcd_memory_alloc(struct ufs_hba *hba)
 						    &hba->utmrdl_dma_addr,
 						    GFP_KERNEL);
 	if (!hba->utmrdl_base_addr ||
-	    WARN_ON(hba->utmrdl_dma_addr & (PAGE_SIZE - 1))) {
+	    WARN_ON(hba->utmrdl_dma_addr & (1024 - 1))) {
 		dev_err(hba->dev,
 		"Task Management Descriptor Memory allocation failed\n");
 		goto out;
-- 
2.25.1