linux-kernel - [PATCH 5/5] iommu/vt-d: Link cache tags of same iommu unit together

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250107021746.6908-6-baolu.lu@linux.intel.com>
Date: Tue,  7 Jan 2025 10:17:46 +0800
From: Lu Baolu <baolu.lu@...ux.intel.com>
To: Joerg Roedel <joro@...tes.org>
Cc: Jason Gunthorpe <jgg@...dia.com>,
	Kees Bakker <kees@...erbout.nl>,
	Zhenzhong Duan <zhenzhong.duan@...el.com>,
	iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: [PATCH 5/5] iommu/vt-d: Link cache tags of same iommu unit together

From: Zhenzhong Duan <zhenzhong.duan@...el.com>

Cache tag invalidation requests for a domain are accumulated until a
different iommu unit is found when traversing the cache_tags linked list.
But cache tags of same iommu unit can be distributed in the linked list,
this make batched flush less efficient. E.g., one device backed by iommu0
is attached to a domain in between two devices attaching backed by iommu1.

Group cache tags together for same iommu unit in cache_tag_assign() to
maximize the performance of batched flush.

Co-developed-by: Lu Baolu <baolu.lu@...ux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...el.com>
Link: https://lore.kernel.org/r/20241219054358.8654-1-zhenzhong.duan@intel.com
---
 drivers/iommu/intel/cache.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/cache.c b/drivers/iommu/intel/cache.c
index 09694cca8752..fc35cba59145 100644
--- a/drivers/iommu/intel/cache.c
+++ b/drivers/iommu/intel/cache.c
@@ -47,6 +47,7 @@ static int cache_tag_assign(struct dmar_domain *domain, u16 did,
 	struct device_domain_info *info = dev_iommu_priv_get(dev);
 	struct intel_iommu *iommu = info->iommu;
 	struct cache_tag *tag, *temp;
+	struct list_head *prev;
 	unsigned long flags;
 
 	tag = kzalloc(sizeof(*tag), GFP_KERNEL);
@@ -65,6 +66,7 @@ static int cache_tag_assign(struct dmar_domain *domain, u16 did,
 		tag->dev = iommu->iommu.dev;
 
 	spin_lock_irqsave(&domain->cache_lock, flags);
+	prev = &domain->cache_tags;
 	list_for_each_entry(temp, &domain->cache_tags, node) {
 		if (cache_tage_match(temp, did, iommu, dev, pasid, type)) {
 			temp->users++;
@@ -73,8 +75,15 @@ static int cache_tag_assign(struct dmar_domain *domain, u16 did,
 			trace_cache_tag_assign(temp);
 			return 0;
 		}
+		if (temp->iommu == iommu)
+			prev = &temp->node;
 	}
-	list_add_tail(&tag->node, &domain->cache_tags);
+	/*
+	 * Link cache tags of same iommu unit together, so corresponding
+	 * flush ops can be batched for iommu unit.
+	 */
+	list_add(&tag->node, prev);
+
 	spin_unlock_irqrestore(&domain->cache_lock, flags);
 	trace_cache_tag_assign(tag);
 
-- 
2.43.0