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iommu_gas: make placeholder entry at the start of the GAS zero size

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same as the placeholder at the end.  This is required to allow GAS to
start at zero, for integration with vmm.

Also, in iommu_gas_remove(), accept placeholders after remove op.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2023-12-23 00:19:05 +02:00
parent 273b4de346
commit f591287756
1 changed files with 6 additions and 13 deletions
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19
sys/dev/iommu/iommu_gas.c
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@ -118,7 +118,7 @@ static int
iommu_gas_cmp_entries(struct iommu_map_entry *a, struct iommu_map_entry *b)
{
/* Last entry have zero size, so <= */
/* First and last entries have zero size, so <= */
KASSERT(a->start <= a->end, ("inverted entry %p (%jx, %jx)",
a, (uintmax_t)a->start, (uintmax_t)a->end));
KASSERT(b->start <= b->end, ("inverted entry %p (%jx, %jx)",
@ -244,25 +244,17 @@ iommu_gas_init_domain(struct iommu_domain *domain)
KASSERT(RB_EMPTY(&domain->rb_root),
("non-empty entries %p", domain));
/*
* The end entry must be inserted first because it has a zero-length gap
* between start and end. Initially, all augmentation data for a new
* entry is zero. Function iommu_gas_augment_entry will compute no
* change in the value of (start-end) and no change in the value of
* free_down, so it will return false to suggest that nothing changed in
* the entry. Thus, inserting the end entry second prevents
* augmentation information to be propogated to the begin entry at the
* tree root. So it is inserted first.
*/
end->start = domain->end;
end->end = domain->end;
end->flags = IOMMU_MAP_ENTRY_PLACE | IOMMU_MAP_ENTRY_UNMAPPED;
RB_INSERT(iommu_gas_entries_tree, &domain->rb_root, end);
begin->start = 0;
begin->end = IOMMU_PAGE_SIZE;
begin->end = 0;
begin->flags = IOMMU_MAP_ENTRY_PLACE | IOMMU_MAP_ENTRY_UNMAPPED;
RB_INSERT_PREV(iommu_gas_entries_tree, &domain->rb_root, end, begin);
iommu_gas_augment_entry(end);
iommu_gas_augment_entry(begin);
domain->start_gap = begin;
domain->first_place = begin;
@ -739,7 +731,8 @@ iommu_gas_remove_locked(struct iommu_domain *domain,
#ifdef INVARIANTS
RB_FOREACH(entry, iommu_gas_entries_tree, &domain->rb_root) {
if ((entry->flags & IOMMU_MAP_ENTRY_RMRR) != 0)
if ((entry->flags & (IOMMU_MAP_ENTRY_RMRR |
IOMMU_MAP_ENTRY_PLACE)) != 0)
continue;
KASSERT(entry->end <= start || entry->start >= end,
("iommu_gas_remove leftover entry (%#jx, %#jx) range "