On Mon, Oct 09, 2023 at 12:13:52PM +0800, Yi Liu wrote:
On 2023/10/7 18:08, Yan Zhao wrote:
On Thu, Sep 21, 2023 at 12:51:24AM -0700, Yi Liu wrote:
From: Nicolin Chen nicolinc@nvidia.com
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@nvidia.com Signed-off-by: Yi Liu yi.l.liu@intel.com
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?
yes.
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.
not quite get this sentence.
I mean with this union, hwpt->auto_domain or hwpt->ioas should only be accessed if and only if hwpt type is kernel-managed. So, any unconditional access, as in iommufd_hw_pagetable_put() pasted below, is buggy.
Therefore, do you think it's better to add a filed like "bool kernel_managed : 1", and access the union fields under /* kernel-managed */ only when hwpt->kernel_managed is true.
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);this is true. this assert is not needed when hwpt is not kernel managed domain.
if (!hwpt->user_managed && hwpt->auto_domain)actually, checking auto_domain is more precise. There is hwpt which is neither user managed nor auto.
auto_domain is under union fields marked with kernel-managed only. Access it without type checking is invalid.
struct iommufd_hw_pagetable { struct iommufd_object obj; struct iommu_domain *domain;
void (*abort)(struct iommufd_object *obj); void (*destroy)(struct iommufd_object *obj);
bool user_managed : 1; union { struct { /* user-managed */ struct iommufd_hw_pagetable *parent; }; struct { /* kernel-managed */ struct iommufd_ioas *ioas; struct mutex mutex; bool auto_domain : 1; bool enforce_cache_coherency : 1; bool msi_cookie : 1; bool nest_parent : 1; /* Head at iommufd_ioas::hwpt_list */ struct list_head hwpt_item; }; }; };
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
-- Regards, Yi Liu