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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Sanjay Kumar <sanjay.k.kumar@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Vinod Koul <vkoul@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 005/103] dmaengine: idxd: Fix clobbering of SWERR overflow bit on writeback
Date:   Mon, 19 Apr 2021 15:05:16 +0200
Message-Id: <20210419130527.964489080@linuxfoundation.org>
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From: Dave Jiang <dave.jiang@intel.com>

[ Upstream commit ea941ac294d75d0ace50797aebf0056f6f8f7a7f ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 552e2e270705..6bb1c1773aae 100644
--- a/drivers/dma/idxd/irq.c
+++ b/drivers/dma/idxd/irq.c
@@ -66,7 +66,9 @@ 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;
-- 
2.30.2