iommu/vt-d: Don't set then clear private data in prq_event_thread()

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>

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 54db589..46776db 100644 (file)
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -1034,12 +1034,12 @@ 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: