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From: Lu Baolu <baolu.lu@linux.intel.com>
To: Joerg Roedel <joro@8bytes.org>, Jason Gunthorpe <jgg@nvidia.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Kevin Tian <kevin.tian@intel.com>
Cc: iommu@lists.linux-foundation.org,
	Jacob jun Pan <jacob.jun.pan@intel.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 2/5] iommu/vt-d: Set SNP bit only in second-level page table entries
Date: Sun,  1 May 2022 19:24:31 +0800	[thread overview]
Message-ID: <20220501112434.874236-3-baolu.lu@linux.intel.com> (raw)
In-Reply-To: <20220501112434.874236-1-baolu.lu@linux.intel.com>

The SNP bit is only valid for second-level PTEs. Setting this bit in the
first-level PTEs has no functional impact because the Intel IOMMU always
ignores the same bit in first-level PTEs. Anyway, let's check the page
table type before setting SNP bit in PTEs to make the code more readable.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index d68f5bbf3e93..98050943d863 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4431,7 +4431,7 @@ static int intel_iommu_map(struct iommu_domain *domain,
 		prot |= DMA_PTE_READ;
 	if (iommu_prot & IOMMU_WRITE)
 		prot |= DMA_PTE_WRITE;
-	if (dmar_domain->force_snooping)
+	if (dmar_domain->force_snooping && !domain_use_first_level(dmar_domain))
 		prot |= DMA_PTE_SNP;
 
 	max_addr = iova + size;
-- 
2.25.1

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WARNING: multiple messages have this Message-ID (diff)
From: Lu Baolu <baolu.lu@linux.intel.com>
To: Joerg Roedel <joro@8bytes.org>, Jason Gunthorpe <jgg@nvidia.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Kevin Tian <kevin.tian@intel.com>
Cc: Jacob jun Pan <jacob.jun.pan@intel.com>,
	Liu Yi L <yi.l.liu@intel.com>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	Lu Baolu <baolu.lu@linux.intel.com>
Subject: [PATCH 2/5] iommu/vt-d: Set SNP bit only in second-level page table entries
Date: Sun,  1 May 2022 19:24:31 +0800	[thread overview]
Message-ID: <20220501112434.874236-3-baolu.lu@linux.intel.com> (raw)
In-Reply-To: <20220501112434.874236-1-baolu.lu@linux.intel.com>

The SNP bit is only valid for second-level PTEs. Setting this bit in the
first-level PTEs has no functional impact because the Intel IOMMU always
ignores the same bit in first-level PTEs. Anyway, let's check the page
table type before setting SNP bit in PTEs to make the code more readable.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index d68f5bbf3e93..98050943d863 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4431,7 +4431,7 @@ static int intel_iommu_map(struct iommu_domain *domain,
 		prot |= DMA_PTE_READ;
 	if (iommu_prot & IOMMU_WRITE)
 		prot |= DMA_PTE_WRITE;
-	if (dmar_domain->force_snooping)
+	if (dmar_domain->force_snooping && !domain_use_first_level(dmar_domain))
 		prot |= DMA_PTE_SNP;
 
 	max_addr = iova + size;
-- 
2.25.1


  parent reply	other threads:[~2022-05-01 11:27 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-01 11:24 [PATCH 0/5] iommu/vt-d: Force snooping improvement Lu Baolu
2022-05-01 11:24 ` Lu Baolu
2022-05-01 11:24 ` [PATCH 1/5] iommu/vt-d: Block force-snoop domain attaching if no SC support Lu Baolu
2022-05-01 11:24   ` Lu Baolu
2022-05-02 13:04   ` Jason Gunthorpe via iommu
2022-05-02 13:04     ` Jason Gunthorpe
2022-05-01 11:24 ` Lu Baolu [this message]
2022-05-01 11:24   ` [PATCH 2/5] iommu/vt-d: Set SNP bit only in second-level page table entries Lu Baolu
2022-05-02 13:05   ` Jason Gunthorpe via iommu
2022-05-02 13:05     ` Jason Gunthorpe
2022-05-04  7:25     ` Baolu Lu
2022-05-04  7:25       ` Baolu Lu
2022-05-04 13:31       ` Jason Gunthorpe via iommu
2022-05-04 13:31         ` Jason Gunthorpe
2022-05-04 14:37         ` Baolu Lu
2022-05-04 14:37           ` Baolu Lu
2022-05-01 11:24 ` [PATCH 3/5] iommu/vt-d: Check domain force_snooping against attached devices Lu Baolu
2022-05-01 11:24   ` Lu Baolu
2022-05-02 13:17   ` Jason Gunthorpe via iommu
2022-05-02 13:17     ` Jason Gunthorpe
2022-05-04  7:58     ` Baolu Lu
2022-05-04  7:58       ` Baolu Lu
2022-05-02 21:31   ` Jacob Pan
2022-05-02 21:31     ` Jacob Pan
2022-05-04  8:06     ` Baolu Lu
2022-05-04  8:06       ` Baolu Lu
2022-05-01 11:24 ` [PATCH 4/5] iommu/vt-d: Remove domain_update_iommu_snooping() Lu Baolu
2022-05-01 11:24   ` Lu Baolu
2022-05-02 13:19   ` Jason Gunthorpe via iommu
2022-05-02 13:19     ` Jason Gunthorpe
2022-05-02 21:36   ` Jacob Pan
2022-05-02 21:36     ` Jacob Pan
2022-05-04  8:47     ` Baolu Lu
2022-05-04  8:47       ` Baolu Lu
2022-05-01 11:24 ` [PATCH 5/5] iommu/vt-d: Remove hard coding PGSNP bit in PASID entries Lu Baolu
2022-05-01 11:24   ` Lu Baolu
2022-05-02 13:19   ` Jason Gunthorpe via iommu
2022-05-02 13:19     ` Jason Gunthorpe
2022-05-04  8:49     ` Baolu Lu
2022-05-04  8:49       ` Baolu Lu

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