| Message ID | b409d9a17c52dc0db51faee91d92737bb7975f5b.1685637456.git.robin.murphy@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iommu/arm-smmu-v3: Set TTL invalidation hint better | expand |
On Thu, 1 Jun 2023 17:43:33 +0100, Robin Murphy wrote: > 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. > > [...] Applied to will (for-joerg/arm-smmu/updates), thanks! [1/1] iommu/arm-smmu-v3: Set TTL invalidation hint better https://git.kernel.org/will/c/6833b8f2e199 Cheers,
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; }
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(-)