linux-kernel - [PATCH 09/17] iommu/vt-d: Use non-privileged mode for all PASIDs

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Date:   Tue, 11 Apr 2023 14:48:07 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     Vinod Koul <vkoul@...nel.org>, Tina Zhang <tina.zhang@...el.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        iommu@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH 09/17] iommu/vt-d: Use non-privileged mode for all PASIDs

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

Supervisor Request Enable (SRE) bit in a PASID entry is for permission
checking on DMA requests. When SRE = 0, DMA with supervisor privilege
will be blocked. However, for in-kernel DMA this is not necessary in that
we are targeting kernel memory anyway. There's no need to differentiate
user and kernel for in-kernel DMA.

Let's use non-privileged (user) permission for all PASIDs used in kernel,
it will be consistent with DMA without PASID (RID_PASID) as well.

Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Link: https://lore.kernel.org/r/20230331231137.1947675-2-jacob.jun.pan@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel/iommu.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index c771233d6f2a..f4e536fd5a28 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2316,8 +2316,6 @@ static int domain_setup_first_level(struct intel_iommu *iommu,
 	if (level != 4 && level != 5)
 		return -EINVAL;
 
-	if (pasid != PASID_RID2PASID)
-		flags |= PASID_FLAG_SUPERVISOR_MODE;
 	if (level == 5)
 		flags |= PASID_FLAG_FL5LP;
 
-- 
2.34.1