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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, Jacob Pan <jacob.jun.pan@linux.intel.com>,
        Liu Yi L <yi.l.liu@intel.com>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <jroedel@suse.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.12 491/677] iommu/vt-d: Dont set then clear private data in prq_event_thread()
Date:   Wed, 12 May 2021 16:48:57 +0200
Message-Id: <20210512144853.696056276@linuxfoundation.org>
In-Reply-To: <20210512144837.204217980@linuxfoundation.org>
References: <20210512144837.204217980@linuxfoundation.org>
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From: Lu Baolu <baolu.lu@linux.intel.com>

[ Upstream commit 1d421058c815d54113d9afdf6db3f995c788cf0d ]

The VT-d specification (section 7.6) requires that the value in the
Private Data field of a Page Group Response Descriptor must match
the value in the Private Data field of the respective Page Request
Descriptor.

The private data field of a page group response descriptor is set then
immediately cleared in prq_event_thread(). This breaks the rule defined
by the VT-d specification. Fix it by moving clearing code up.

Fixes: 5b438f4ba315d ("iommu/vt-d: Support page request in scalable mode")
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Liu Yi L <yi.l.liu@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210320024156.640798-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/iommu/intel/svm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 4627437ae1c0..547a6cf57057 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -1031,12 +1031,12 @@ no_pasid:
 				QI_PGRP_RESP_TYPE;
 			resp.qw1 = QI_PGRP_IDX(req->prg_index) |
 				QI_PGRP_LPIG(req->lpig);
+			resp.qw2 = 0;
+			resp.qw3 = 0;
 
 			if (req->priv_data_present)
 				memcpy(&resp.qw2, req->priv_data,
 				       sizeof(req->priv_data));
-			resp.qw2 = 0;
-			resp.qw3 = 0;
 			qi_submit_sync(iommu, &resp, 1, 0);
 		}
 prq_advance:
-- 
2.30.2