On Thu, Mar 09, 2023 at 12:22:05AM -0800, Yi Liu wrote:
> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
>
> The nested domain fields are exclusive to those that used for a DMA
> remapping domain. Use union to avoid memory waste.
>
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> ---
> drivers/iommu/intel/iommu.h | 35 +++++++++++++++++++++++++++++------
> 1 file changed, 29 insertions(+), 6 deletions(-)
Using unions like this often devolves into a mess.
You'd be better to have more structures
struct intel_iommu_domain {
struct iommu_domain domain;
[general fields about attachment]
};
struct intel_iopte_domain {
struct intel_iommu_domain domain;
[stuff describing the io page table data, pgd, format, etc]
};
strut intel_s1_domain {
struct intel_iommu_domain domain;
struct dmar_domain *s2_domain;
/* user page table pointer (in GPA) */
unsigned long s1_pgtbl;
/* page table attributes */
struct iommu_hwpt_intel_vtd s1_cfg;
};
static_assert(offset_of(struct intel_s1_domain, domain.domain) ==
offset_of(struct intel_iommu_domain, domain));
The per-domain ops allow to make this work sensibly
Jason
