From: Lu Baolu <baolu.lu@linux.intel.com>
Date: Sat, 20 Mar 2021 10:41:56 +0800
Subject: iommu/vt-d: Don't set then clear private data in prq_event_thread()
Git-commit: 1d421058c815d54113d9afdf6db3f995c788cf0d
Patch-mainline: v5.13-rc1
References: bsc#1189217

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>
---
 drivers/iommu/intel-svm.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -679,12 +679,12 @@ static irqreturn_t prq_event_thread(int
 				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(&resp, iommu);
 		}
 		head = (head + sizeof(*req)) & PRQ_RING_MASK;