Re: [PATCH v1] iommu/hyperv: Don't free a paging domain the hypervisor did not delete

[Easwar Hariharan]

On 11/5/2026 11:27, Yuho Choi wrote:
> hv_iommu_paging_domain_free() frees all page-table pages with
> pt_iommu_deinit() and only then asks the hypervisor to delete the
> device domain that points at them. If HVCALL_DELETE_DEVICE_DOMAIN
> fails, hv_delete_device_domain() only logs the error, returns the
> domain ID to the IDA, and the domain is freed anyway.
> 
> The hypervisor then keeps a device domain whose page tables have been
> freed and can be reused for anything. The ID is also handed out again
> by the next paging domain allocation, while the hypervisor still has a
> domain with that ID.
> 
> Delete the domain before freeing its page tables, and keep the ID, the
> page tables and the domain if the hypervisor fails to delete it.
> 
> Fixes: 2690d4156b51 ("iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest")
> Signed-off-by: Yuho Choi <oss.patchbox@xxxxxxxxx>
> ---
> Compile-tested only (x86_64 with HYPERV and HYPERV_PVIOMMU,
> W=1); I have no Hyper-V guest with the para-virtualized IOMMU to test
> it on.
> 
>  drivers/iommu/hyperv/hv-iommu-guest.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
Good catch!

Reviewed-by: Easwar Hariharan <easwar.hariharan@xxxxxxxxxxxxxxxxxxx>