From ea941ac294d75d0ace50797aebf0056f6f8f7a7f Mon Sep 17 00:00:00 2001
From: Dave Jiang <dave.jiang@intel.com>
Date: Tue, 16 Feb 2021 17:13:42 -0700
Subject: [PATCH] dmaengine: idxd: Fix clobbering of SWERR overflow bit on writeback
Git-commit: ea941ac294d75d0ace50797aebf0056f6f8f7a7f
Patch-mainline: v5.12
References: git-fixes

Current code blindly writes over the SWERR and the OVERFLOW bits. Write
back the bits actually read instead so the driver avoids clobbering the
OVERFLOW bit that comes after the register is read.

Fixes: bfe1d56091c1 ("dmaengine: idxd: Init and probe for Intel data accelerators")
Reported-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/161352082229.3511254.1002151220537623503.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/dma/idxd/irq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c
index a60ca11a5784..f1463fc58112 100644
--- a/drivers/dma/idxd/irq.c
+++ b/drivers/dma/idxd/irq.c
@@ -124,7 +124,9 @@ static int process_misc_interrupts(struct idxd_device *idxd, u32 cause)
 		for (i = 0; i < 4; i++)
 			idxd->sw_err.bits[i] = ioread64(idxd->reg_base +
 					IDXD_SWERR_OFFSET + i * sizeof(u64));
-		iowrite64(IDXD_SWERR_ACK, idxd->reg_base + IDXD_SWERR_OFFSET);
+
+		iowrite64(idxd->sw_err.bits[0] & IDXD_SWERR_ACK,
+			  idxd->reg_base + IDXD_SWERR_OFFSET);
 
 		if (idxd->sw_err.valid && idxd->sw_err.wq_idx_valid) {
 			int id = idxd->sw_err.wq_idx;
-- 
2.26.2