linux-kernel - [PATCH 4/4] iommu/vt-d: Calculate and set flags for handle_mm

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Date:   Thu, 18 Feb 2021 13:31:18 -0800
From:   Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:     LKML <linux-kernel@...r.kernel.org>,
        iommu@...ts.linux-foundation.org, Joerg Roedel <joro@...tes.org>,
        "Lu Baolu" <baolu.lu@...ux.intel.com>
Cc:     Yi Liu <yi.l.liu@...el.com>, Raj Ashok <ashok.raj@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>, Wu Hao <hao.wu@...el.com>,
        Yi Sun <yi.y.sun@...el.com>, Dave Jiang <dave.jiang@...el.com>,
        Eric Auger <eric.auger@...hat.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: [PATCH 4/4] iommu/vt-d: Calculate and set flags for handle_mm_fault

Page requests are originated from the user page fault. Therefore, we
shall set FAULT_FLAG_USER. 

FAULT_FLAG_REMOTE indicates that we are walking an mm which is not
guaranteed to be the same as the current->mm and should not be subject
to protection key enforcement. Therefore, we should set FAULT_FLAG_REMOTE
to avoid faults when both SVM and PKEY are used.

References: commit 1b2ee1266ea6 ("mm/core: Do not enforce PKEY permissions on remote mm access")
Reviewed-by: Raj Ashok <ashok.raj@...el.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
---
 drivers/iommu/intel/svm.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index ff7ae7cc17d5..7bfd20a24a60 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -1086,6 +1086,7 @@ static irqreturn_t prq_event_thread(int irq, void *d)
 	struct intel_iommu *iommu = d;
 	struct intel_svm *svm = NULL;
 	int head, tail, handled = 0;
+	unsigned int flags = 0;
 
 	/* Clear PPR bit before reading head/tail registers, to
 	 * ensure that we get a new interrupt if needed. */
@@ -1186,9 +1187,11 @@ static irqreturn_t prq_event_thread(int irq, void *d)
 		if (access_error(vma, req))
 			goto invalid;
 
-		ret = handle_mm_fault(vma, address,
-				      req->wr_req ? FAULT_FLAG_WRITE : 0,
-				      NULL);
+		flags = FAULT_FLAG_USER | FAULT_FLAG_REMOTE;
+		if (req->wr_req)
+			flags |= FAULT_FLAG_WRITE;
+
+		ret = handle_mm_fault(vma, address, flags, NULL);
 		if (ret & VM_FAULT_ERROR)
 			goto invalid;
 
-- 
2.25.1