linux-kernel - [PATCH 1/1] iommu/vt-d: Remove LPIG from page group response descriptor

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Message-ID: <20250901053943.1708490-1-baolu.lu@linux.intel.com>
Date: Mon,  1 Sep 2025 13:39:43 +0800
From: Lu Baolu <baolu.lu@...ux.intel.com>
To: Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	Kevin Tian <kevin.tian@...el.com>,
	Jason Gunthorpe <jgg@...dia.com>
Cc: iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 1/1] iommu/vt-d: Remove LPIG from page group response descriptor

Bit 66 in the page group response descriptor used to be the LPIG (Last
Page in Group), but it was marked as Reserved since Specification 4.0.
Remove programming on this bit to make it consistent with the latest
specification.

Existing hardware all treats bit 66 of the page group response descriptor
as "ignored", therefore this change doesn't break any existing hardware.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel/iommu.h | 1 -
 drivers/iommu/intel/prq.c   | 7 ++-----
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index d09b92871659..2a3931c4cff9 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -462,7 +462,6 @@ enum {
 #define QI_PGRP_PASID(pasid)	(((u64)(pasid)) << 32)
 
 /* Page group response descriptor QW1 */
-#define QI_PGRP_LPIG(x)		(((u64)(x)) << 2)
 #define QI_PGRP_IDX(idx)	(((u64)(idx)) << 3)
 
 
diff --git a/drivers/iommu/intel/prq.c b/drivers/iommu/intel/prq.c
index 52570e42a14c..ff63c228e6e1 100644
--- a/drivers/iommu/intel/prq.c
+++ b/drivers/iommu/intel/prq.c
@@ -151,8 +151,7 @@ static void handle_bad_prq_event(struct intel_iommu *iommu,
 			QI_PGRP_PASID_P(req->pasid_present) |
 			QI_PGRP_RESP_CODE(result) |
 			QI_PGRP_RESP_TYPE;
-	desc.qw1 = QI_PGRP_IDX(req->prg_index) |
-			QI_PGRP_LPIG(req->lpig);
+	desc.qw1 = QI_PGRP_IDX(req->prg_index);
 
 	qi_submit_sync(iommu, &desc, 1, 0);
 }
@@ -379,19 +378,17 @@ void intel_iommu_page_response(struct device *dev, struct iopf_fault *evt,
 	struct iommu_fault_page_request *prm;
 	struct qi_desc desc;
 	bool pasid_present;
-	bool last_page;
 	u16 sid;
 
 	prm = &evt->fault.prm;
 	sid = PCI_DEVID(bus, devfn);
 	pasid_present = prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
-	last_page = prm->flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE;
 
 	desc.qw0 = QI_PGRP_PASID(prm->pasid) | QI_PGRP_DID(sid) |
 			QI_PGRP_PASID_P(pasid_present) |
 			QI_PGRP_RESP_CODE(msg->code) |
 			QI_PGRP_RESP_TYPE;
-	desc.qw1 = QI_PGRP_IDX(prm->grpid) | QI_PGRP_LPIG(last_page);
+	desc.qw1 = QI_PGRP_IDX(prm->grpid);
 	desc.qw2 = 0;
 	desc.qw3 = 0;
 
-- 
2.43.0