linux-kernel - [PATCH 5.10 388/530] iommu/vt-d: Dont set then clear private data in prq_event

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Date:   Wed, 12 May 2021 16:48:18 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Liu Yi L <yi.l.liu@...el.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <jroedel@...e.de>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 388/530] iommu/vt-d: Dont set then clear private data in prq_event_thread()

From: Lu Baolu <baolu.lu@...ux.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@...ux.intel.com>
Reviewed-by: Liu Yi L <yi.l.liu@...el.com>
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
Link: https://lore.kernel.org/r/20210320024156.640798-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.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 5c95e9693bf5..d79639b5b8a9 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -1071,12 +1071,12 @@ 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