On Thu, Sep 21, 2023 at 12:51:24AM -0700, Yi Liu wrote:
> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
>
> The struct iommufd_hw_pagetable has been representing a kernel-managed
> HWPT, yet soon will be reused to represent a user-managed HWPT. These
> two types of HWPTs has the same IOMMUFD object type and an iommu_domain
> object, but have quite different attributes/members.
>
> Add a union in struct iommufd_hw_pagetable and group all the existing
> kernel-managed members. One of the following patches will add another
> struct for user-managed members.
>
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> ---
> drivers/iommu/iommufd/iommufd_private.h | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
> index 3064997a0181..947a797536e3 100644
> --- a/drivers/iommu/iommufd/iommufd_private.h
> +++ b/drivers/iommu/iommufd/iommufd_private.h
> @@ -231,13 +231,18 @@ int iommufd_vfio_ioas(struct iommufd_ucmd *ucmd);
> */
> struct iommufd_hw_pagetable {
> struct iommufd_object obj;
> - struct iommufd_ioas *ioas;
> struct iommu_domain *domain;
> - bool auto_domain : 1;
> - bool enforce_cache_coherency : 1;
> - bool msi_cookie : 1;
> - /* Head at iommufd_ioas::hwpt_list */
> - struct list_head hwpt_item;
> +
> + union {
> + struct { /* kernel-managed */
> + struct iommufd_ioas *ioas;
> + bool auto_domain : 1;
Will iommufd_hw_pagetable_put() also be called on non-kernel-managed domain?
If yes, hwpt->user_managed needs to be checked in iommufd_hw_pagetable_put(),
(e.g. as below).
Otherwise, this union will lead to hwpt->ioas and hwpt->auto_domain still being
accessible though invalid.
static inline void iommufd_hw_pagetable_put(struct iommufd_ctx *ictx,
struct iommufd_hw_pagetable *hwpt)
{
- lockdep_assert_not_held(&hwpt->ioas->mutex);
- if (hwpt->auto_domain)
+ if (!hwpt->user_managed)
+ lockdep_assert_not_held(&hwpt->ioas->mutex);
+
+ if (!hwpt->user_managed && hwpt->auto_domain)
iommufd_object_deref_user(ictx, &hwpt->obj);
else
refcount_dec(&hwpt->obj.users);
}
> + bool enforce_cache_coherency : 1;
> + bool msi_cookie : 1;
> + /* Head at iommufd_ioas::hwpt_list */
> + struct list_head hwpt_item;
> + };
> + };
> };
>
> struct iommufd_hw_pagetable *
> --
> 2.34.1
>
