linux-kernel - [PATCH 03/12] iommu/vt-d: Remove clearing translation data in disable_dmar

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Date:   Fri, 27 May 2022 14:30:10 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>, Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Christoph Hellwig <hch@...radead.org>,
        Jason Gunthorpe <jgg@...dia.com>
Cc:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 03/12] iommu/vt-d: Remove clearing translation data in disable_dmar_iommu()

The disable_dmar_iommu() is called when IOMMU initialzation fails or
the IOMMU is hot-removed from the system. In both cases, there is no
need to clear the IOMMU translation data structures for devices.

On the initialization path, the device probing only happens after the
IOMMU is initialized successfully, hence there're no translation data
structures.

On the hot-remove path, there is no real use case where the IOMMU is
hot-removed, but the devices that it manages are still alive in the
system. The translation data structures were torn down during device
release, hence there's no need to repeat it in IOMMU hot-remove path
either.

So, let's remove this unnecessary code.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel/iommu.c | 15 ---------------
 1 file changed, 15 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 6549b09d7f32..25d4c5200526 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1715,24 +1715,9 @@ static int iommu_init_domains(struct intel_iommu *iommu)
 
 static void disable_dmar_iommu(struct intel_iommu *iommu)
 {
-	struct device_domain_info *info, *tmp;
-	unsigned long flags;
-
 	if (!iommu->domain_ids)
 		return;
 
-	spin_lock_irqsave(&device_domain_lock, flags);
-	list_for_each_entry_safe(info, tmp, &device_domain_list, global) {
-		if (info->iommu != iommu)
-			continue;
-
-		if (!info->dev || !info->domain)
-			continue;
-
-		__dmar_remove_one_dev_info(info);
-	}
-	spin_unlock_irqrestore(&device_domain_lock, flags);
-
 	if (iommu->gcmd & DMA_GCMD_TE)
 		iommu_disable_translation(iommu);
 }
-- 
2.25.1