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Message-ID: <ZSEuBcLaSq4NjoC8@yzhao56-desk.sh.intel.com>
Date: Sat, 7 Oct 2023 18:08:05 +0800
From: Yan Zhao <yan.y.zhao@...el.com>
To: Yi Liu <yi.l.liu@...el.com>
CC: <joro@...tes.org>, <alex.williamson@...hat.com>, <jgg@...dia.com>,
<kevin.tian@...el.com>, <robin.murphy@....com>,
<baolu.lu@...ux.intel.com>, <cohuck@...hat.com>,
<eric.auger@...hat.com>, <nicolinc@...dia.com>,
<kvm@...r.kernel.org>, <mjrosato@...ux.ibm.com>,
<chao.p.peng@...ux.intel.com>, <yi.y.sun@...ux.intel.com>,
<peterx@...hat.com>, <jasowang@...hat.com>,
<shameerali.kolothum.thodi@...wei.com>, <lulu@...hat.com>,
<suravee.suthikulpanit@....com>, <iommu@...ts.linux.dev>,
<linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
<zhenzhong.duan@...el.com>, <joao.m.martins@...cle.com>
Subject: Re: [PATCH v4 03/17] iommufd: Unite all kernel-managed members into
a struct
On Thu, Sep 21, 2023 at 12:51:24AM -0700, Yi Liu wrote:
> From: Nicolin Chen <nicolinc@...dia.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@...dia.com>
> Signed-off-by: Yi Liu <yi.l.liu@...el.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?
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
>
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