linux-kernel - [RESEND PATCH v3 0/4] iommu/iova: Solve longterm IOVA issue

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Date:   Tue, 17 Nov 2020 18:25:30 +0800
From:   John Garry <john.garry@...wei.com>
To:     <robin.murphy@....com>, <joro@...tes.org>, <will@...nel.org>
CC:     <xiyou.wangcong@...il.com>, <linuxarm@...wei.com>,
        <iommu@...ts.linux-foundation.org>, <linux-kernel@...r.kernel.org>,
        <chenxiang66@...ilicon.com>, John Garry <john.garry@...wei.com>
Subject: [RESEND PATCH v3 0/4] iommu/iova: Solve longterm IOVA issue

This series contains a patch to solve the longterm IOVA issue which
leizhen originally tried to address at [0].

A sieved kernel log is at the following, showing periodic dumps of IOVA
sizes, per CPU and per depot bin, per IOVA size granule:
https://raw.githubusercontent.com/hisilicon/kernel-dev/topic-iommu-5.10-iova-debug-v3/aging_test

Notice, for example, the following logs:
[13175.355584] print_iova1 cpu_total=40135 depot_total=3866 total=44001
[83483.457858] print_iova1 cpu_total=62532 depot_total=24476 total=87008

Where total IOVA rcache size has grown from 44K->87K over a long time.

Along with this patch, I included the following:
- A smaller helper to clear all IOVAs for a domain
- Change polarity of the IOVA magazine helpers
- Small optimisation from Cong Wang included, which was never applied [1].
  There was some debate of the other patches in that series, but this one
  is quite straightforward.

Differnces to v2:
- Update commit message for patch 3/4

Differences to v1:
- Add IOVA clearing helper
- Add patch to change polarity of mag helpers
- Avoid logically-redundant extra variable in __iova_rcache_insert()

[0] https://lore.kernel.org/linux-iommu/20190815121104.29140-3-thunder.leizhen@huawei.com/
[1] https://lore.kernel.org/linux-iommu/4b74d40a-22d1-af53-fcb6-5d70183705a8@huawei.com/

Cong Wang (1):
  iommu: avoid taking iova_rbtree_lock twice

John Garry (3):
  iommu/iova: Add free_all_cpu_cached_iovas()
  iommu/iova: Avoid double-negatives in magazine helpers
  iommu/iova: Flush CPU rcache for when a depot fills

 drivers/iommu/iova.c | 66 +++++++++++++++++++++++++-------------------
 1 file changed, 38 insertions(+), 28 deletions(-)

-- 
2.26.2