linux-kernel - [PATCH v6 0/7] iommu/amd: Enable page-selective flushes

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Date:   Fri, 23 Jul 2021 02:32:02 -0700
From:   Nadav Amit <nadav.amit@...il.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     John Garry <john.garry@...wei.com>, Nadav Amit <namit@...are.com>,
        Will Deacon <will@...nel.org>,
        Jiajun Cao <caojiajun@...are.com>,
        Robin Murphy <robin.murphy@....com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: [PATCH v6 0/7] iommu/amd: Enable page-selective flushes

From: Nadav Amit <namit@...are.com>

The previous patch, commit 268aa4548277 ("iommu/amd: Page-specific
invalidations for more than one page") was supposed to enable
page-selective IOTLB flushes on AMD.

Besides the bug that was already fixed by commit a017c567915f
("iommu/amd: Fix wrong parentheses on page-specific invalidations")
there are several remaining matters to enable and benefit from
page-selective IOTLB flushes on AMD:

1. Enable selective flushes on unmap (patch 1)
2. Avoid using flush-queue on vIOMMUs (patch 2)
3. Relaxed flushes when gathering, excluding vIOMMUs (patches 3-5)
4. Syncing once on scatter-gather map operations (patch 6)
5. Breaking flushes to naturally aligned ranges on vIOMMU (patch 7)

The main difference in this version is that the logic that flushes
vIOMMU was improved based on Robin's feedback. Batching decisions are
not based on alignment anymore, but instead the flushing range is broken
into naturally aligned regions on sync. Doing so allows us to flush only
the entries that we modified with the minimal number of flushes.

Robin, others: your feedback would be highly appreciated to get these
patches merge.

Cc: Joerg Roedel <joro@...tes.org>
Cc: Will Deacon <will@...nel.org>
Cc: Jiajun Cao <caojiajun@...are.com>
Cc: Robin Murphy <robin.murphy@....com>
Cc: Lu Baolu <baolu.lu@...ux.intel.com>
Cc: iommu@...ts.linux-foundation.org
Cc: linux-kernel@...r.kernel.org

---

v5->v6:
* Remove redundant check on amd_iommu_iotlb_gather_add_page() [Robin]
* Add Robin's reviewed-by tags

v4->v5:
* Rebase on v5.14-rc1
* Change pr_warn() to pr_info() [John Garry]

v3->v4:
* Breaking flushes to naturally aligned ranges on vIOMMU [Robin]
* Removing unnecessary stubs; fixing comment [Robin]
* Removing unused variable [Yong]
* Changing pr_warn_once() to pr_warn() [Robin]
* Improving commit log [Will]

v2->v3:
* Rebase on v5.13-rc5
* Refactoring (patches 4-5) [Robin]
* Rework flush logic (patch 5): more relaxed on native
* Syncing once on scatter-gather operations (patch 6)

v1->v2:
* Rebase on v5.13-rc3

Nadav Amit (6):
  iommu/amd: Selective flush on unmap
  iommu/amd: Do not use flush-queue when NpCache is on
  iommu: Factor iommu_iotlb_gather_is_disjoint() out
  iommu/amd: Tailored gather logic for AMD
  iommu/amd: Sync once for scatter-gather operations
  iommu/amd: Use only natural aligned flushes in a VM

Robin Murphy (1):
  iommu: Improve iommu_iotlb_gather helpers

 drivers/iommu/amd/init.c  |  7 ++-
 drivers/iommu/amd/iommu.c | 96 +++++++++++++++++++++++++++++++++++----
 drivers/iommu/mtk_iommu.c |  6 +--
 include/linux/iommu.h     | 72 +++++++++++++++++++++++------
 4 files changed, 153 insertions(+), 28 deletions(-)

-- 
2.25.1