On 2023/10/9 13:13, Yan Zhao wrote:
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@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?
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.
ok, I get this part. just not sure about the missing words in your prior
comment.
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.
I see. yes, should check user_managed as well. :)
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
--
Regards,
Yi Liu
