From: Robin Murphy <robin.murphy@arm.com>
To: will@kernel.org
Cc: joro@8bytes.org, jean-philippe@linaro.org, iommu@lists.linux.dev,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH] iommu/arm-smmu-v3: Set TTL invalidation hint better
Date: Thu, 1 Jun 2023 17:43:33 +0100 [thread overview]
Message-ID: <b409d9a17c52dc0db51faee91d92737bb7975f5b.1685637456.git.robin.murphy@arm.com> (raw)
When io-pgtable unmaps a whole table, rather than waste time walking it
to find the leaf entries to invalidate exactly, it simply expects
.tlb_flush_walk with nominal last-level granularity to invalidate any
leaf entries at higher intermediate levels as well. This works fine with
page-based invalidation, but with range commands we need to be careful
with the TTL hint - unconditionally setting it based on the given level
3 granule means that an invalidation for a level 1 table would strictly
not be required to affect level 2 block entries. It's easy to comply
with the expected behaviour by simply not setting the TTL hint for
non-leaf invalidations, so let's do that.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 3fd83fb75722..4763e68cc1ab 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1892,8 +1892,13 @@ static void __arm_smmu_tlb_inv_range(struct arm_smmu_cmdq_ent *cmd,
/* Convert page size of 12,14,16 (log2) to 1,2,3 */
cmd->tlbi.tg = (tg - 10) / 2;
- /* Determine what level the granule is at */
- cmd->tlbi.ttl = 4 - ((ilog2(granule) - 3) / (tg - 3));
+ /*
+ * Determine what level the granule is at. For non-leaf, io-pgtable
+ * assumes .tlb_flush_walk can invalidate multiple levels at once,
+ * so ignore the nominal last-level granule and leave TTL=0.
+ */
+ if (cmd->tlbi.leaf)
+ cmd->tlbi.ttl = 4 - ((ilog2(granule) - 3) / (tg - 3));
num_pages = size >> tg;
}
--
2.39.2.101.g768bb238c484.dirty
next reply other threads:[~2023-06-01 16:43 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-01 16:43 Robin Murphy [this message]
2023-06-08 21:36 ` [PATCH] iommu/arm-smmu-v3: Set TTL invalidation hint better Will Deacon
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