linux-kernel - [PATCH 2/2] iommu/iova: Free global iova rcache on iova alloc failure

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Date:   Fri,  3 Jul 2020 19:47:15 +0530
From:   vjitta@...eaurora.org
To:     joro@...tes.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Cc:     vinmenon@...eaurora.org, kernel-team@...roid.com,
        vjitta@...eaurora.org
Subject: [PATCH 2/2] iommu/iova: Free global iova rcache on iova alloc failure

From: Vijayanand Jitta <vjitta@...eaurora.org>

When ever an iova alloc request fails we free the iova
ranges present in the percpu iova rcaches and then retry
but the global iova rcache is not freed as a result we could
still see iova alloc failure even after retry as global
rcache is holding the iova's which can cause fragmentation.
So, free the global iova rcache as well and then go for the
retry.

Change-Id: Ib8236dc88ba5516b73d4fbf6bf8e68bbf09bbad2
Signed-off-by: Vijayanand Jitta <vjitta@...eaurora.org>
---
 drivers/iommu/iova.c | 23 +++++++++++++++++++++++
 include/linux/iova.h |  6 ++++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 4e77116..5836c87 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -442,6 +442,7 @@ struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
 		flush_rcache = false;
 		for_each_online_cpu(cpu)
 			free_cpu_cached_iovas(cpu, iovad);
+		free_global_cached_iovas(iovad);
 		goto retry;
 	}
 
@@ -1055,5 +1056,27 @@ void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad)
 	}
 }
 
+/*
+ * free all the IOVA ranges of global cache
+ */
+void free_global_cached_iovas(struct iova_domain *iovad)
+{
+	struct iova_rcache *rcache;
+	unsigned long flags;
+	int i, j;
+
+	for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
+		rcache = &iovad->rcaches[i];
+		spin_lock_irqsave(&rcache->lock, flags);
+		for (j = 0; j < rcache->depot_size; ++j) {
+			iova_magazine_free_pfns(rcache->depot[j], iovad);
+			iova_magazine_free(rcache->depot[j]);
+			rcache->depot[j] = NULL;
+		}
+		rcache->depot_size = 0;
+		spin_unlock_irqrestore(&rcache->lock, flags);
+	}
+}
+
 MODULE_AUTHOR("Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>");
 MODULE_LICENSE("GPL");
diff --git a/include/linux/iova.h b/include/linux/iova.h
index a0637ab..a905726 100644
--- a/include/linux/iova.h
+++ b/include/linux/iova.h
@@ -163,6 +163,7 @@ int init_iova_flush_queue(struct iova_domain *iovad,
 struct iova *split_and_remove_iova(struct iova_domain *iovad,
 	struct iova *iova, unsigned long pfn_lo, unsigned long pfn_hi);
 void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad);
+void free_global_cached_iovas(struct iova_domain *iovad);
 #else
 static inline int iova_cache_get(void)
 {
@@ -270,6 +271,11 @@ static inline void free_cpu_cached_iovas(unsigned int cpu,
 					 struct iova_domain *iovad)
 {
 }
+
+static inline void free_global_cached_iovas(struct iova_domain *iovad)
+{
+}
+
 #endif
 
 #endif
-- 
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