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iommu/amd: Fix ineffective error check in nested domain allocation

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amd_iommu_pdom_id_alloc() returns an int: a domain ID on success, or the
negative errno from ida_alloc_range() when the ID space is exhausted or
memory is short.  amd_iommu_alloc_domain_nested() stores that return value
in gdom_info->hdom_id, which is a u32, and only then tests it:

	gdom_info->hdom_id = amd_iommu_pdom_id_alloc();
	if (gdom_info->hdom_id <= 0) {

The assignment discards the sign, so -ENOSPC becomes 0xffffffe4 and the
test never fires.  The nested domain is then set up with a host domain ID
that was never allocated, instead of the allocation failing with -ENOSPC.

Keep the value in an int, test it there, and store it only once it is
known to be valid, which is what the other amd_iommu_pdom_id_alloc()
callers already do.

Fixes: 757d2b1fdf ("iommu/amd: Introduce gDomID-to-hDomID Mapping and handle parent domain invalidation")
Signed-off-by: Hemanth Selam <hemanth.selam@gmail.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
This commit is contained in:
Hemanth Selam 2026-08-25 15:35:54 +05:30 committed by Joerg Roedel
parent eb29b7bbc8
commit fa5c0827f0
1 changed files with 4 additions and 3 deletions
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7
drivers/iommu/amd/nested.c
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@ -96,7 +96,7 @@ struct iommu_domain *
amd_iommu_alloc_domain_nested(struct iommufd_viommu *viommu, u32 flags,
const struct iommu_user_data *user_data)
{
int ret;
int ret, hdom_id;
unsigned long irqflags;
struct nested_domain *ndom;
struct guest_domain_mapping_info *gdom_info;
@ -161,8 +161,8 @@ amd_iommu_alloc_domain_nested(struct iommufd_viommu *viommu, u32 flags,
}
/* The gDomID does not exist. We allocate new hdom_id */
gdom_info->hdom_id = amd_iommu_pdom_id_alloc();
if (gdom_info->hdom_id <= 0) {
hdom_id = amd_iommu_pdom_id_alloc();
if (hdom_id <= 0) {
__xa_cmpxchg(&aviommu->gdomid_array,
ndom->gdom_id, gdom_info, NULL, GFP_ATOMIC);
xa_unlock_irqrestore(&aviommu->gdomid_array, irqflags);
@ -170,6 +170,7 @@ amd_iommu_alloc_domain_nested(struct iommufd_viommu *viommu, u32 flags,
goto out_err_gdom_info;
}
gdom_info->hdom_id = hdom_id;
ndom->gdom_info = gdom_info;
refcount_set(&gdom_info->users, 1);