linux-kernel - [PATCH] iommu/iova: Reset max32_alloc_size after cleaning rcache in the fail path

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Date:   Tue, 1 Mar 2022 09:42:43 +0800
From:   <yf.wang@...iatek.com>
To:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        "Matthias Brugger" <matthias.bgg@...il.com>,
        "open list:IOMMU DRIVERS" <iommu@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>
CC:     <wsd_upstream@...iatek.com>, Libo Kang <Libo.Kang@...iatek.com>,
        Ning Li <Ning.Li@...iatek.com>, Yong Wu <Yong.Wu@...iatek.com>,
        Yunfei Wang <yf.wang@...iatek.com>
Subject: [PATCH] iommu/iova: Reset max32_alloc_size after cleaning rcache in the fail path

From: Yunfei Wang <yf.wang@...iatek.com>

In alloc_iova_fast function, if __alloc_and_insert_iova_range fail,
alloc_iova_fast will try flushing rcache and retry alloc iova, but
this has an issue:

Since __alloc_and_insert_iova_range fail will set the current alloc
iova size to max32_alloc_size (iovad->max32_alloc_size = size),
when the retry is executed into the __alloc_and_insert_iova_range
function, the retry action will be blocked by the check condition
(size >= iovad->max32_alloc_size) and goto iova32_full directly,
causes the action of retry regular alloc iova in
__alloc_and_insert_iova_range to not actually be executed.

Based on the above, so need reset max32_alloc_size before retry alloc
iova when alloc iova fail, that is set the initial dma_32bit_pfn value
of iovad to max32_alloc_size, so that the action of retry alloc iova
in __alloc_and_insert_iova_range can be executed.

Signed-off-by: Yunfei Wang <yf.wang@...iatek.com>
---
 drivers/iommu/iova.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index b28c9435b898..0c085ae8293f 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -453,6 +453,7 @@ alloc_iova_fast(struct iova_domain *iovad, unsigned long size,
 retry:
 	new_iova = alloc_iova(iovad, size, limit_pfn, true);
 	if (!new_iova) {
+		unsigned long flags;
 		unsigned int cpu;
 
 		if (!flush_rcache)
@@ -463,6 +464,12 @@ alloc_iova_fast(struct iova_domain *iovad, unsigned long size,
 		for_each_online_cpu(cpu)
 			free_cpu_cached_iovas(cpu, iovad);
 		free_global_cached_iovas(iovad);
+
+		/* Reset max32_alloc_size after flushing rcache for retry */
+		spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
+		iovad->max32_alloc_size = iovad->dma_32bit_pfn;
+		spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
+
 		goto retry;
 	}
 
-- 
2.18.0