linux-kernel - [PATCH 5.12 454/677] iommu/vt-d: Reject unsupported page request modes

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Date:   Wed, 12 May 2021 16:48:20 +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, Lu Baolu <baolu.lu@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Joerg Roedel <jroedel@...e.de>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.12 454/677] iommu/vt-d: Reject unsupported page request modes

From: Jacob Pan <jacob.jun.pan@...ux.intel.com>

[ Upstream commit 78a523fe73b81b4447beb2d6c78c9fafae24eebb ]

When supervisor/privilige mode SVM is used, we bind init_mm.pgd with
a supervisor PASID. There should not be any page fault for init_mm.
Execution request with DMA read is also not supported.

This patch checks PRQ descriptor for both unsupported configurations,
reject them both with invalid responses.

Fixes: 1c4f88b7f1f92 ("iommu/vt-d: Shared virtual address in scalable mode")
Acked-by: Lu Baolu <baolu.lu@...ux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Link: https://lore.kernel.org/r/1614680040-1989-4-git-send-email-jacob.jun.pan@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iommu/intel/svm.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 574a7e657a9a..4627437ae1c0 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -920,7 +920,17 @@ static irqreturn_t prq_event_thread(int irq, void *d)
 			       ((unsigned long long *)req)[1]);
 			goto no_pasid;
 		}
-
+		/* We shall not receive page request for supervisor SVM */
+		if (req->pm_req && (req->rd_req | req->wr_req)) {
+			pr_err("Unexpected page request in Privilege Mode");
+			/* No need to find the matching sdev as for bad_req */
+			goto no_pasid;
+		}
+		/* DMA read with exec requeset is not supported. */
+		if (req->exe_req && req->rd_req) {
+			pr_err("Execution request not supported\n");
+			goto no_pasid;
+		}
 		if (!svm || svm->pasid != req->pasid) {
 			rcu_read_lock();
 			svm = ioasid_find(NULL, req->pasid, NULL);
-- 
2.30.2