| Message ID | 20180801102221.5308-3-nek.in.cn@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | A General Accelerator Framework, WarpDrive | expand |
> From: Kenneth Lee > Sent: Wednesday, August 1, 2018 6:22 PM > > From: Kenneth Lee <liguozhu@hisilicon.com> > > This patch add sharing interface for a iommu_group. The new interface: > > iommu_group_share_domain() > iommu_group_unshare_domain() > > can be used by some virtual iommu_group (such as iommu_group for > spimdev) > to share their parent's iommu_group. > > When the domain of the group is shared, it cannot be changed before > unshared. In the future, notification can be added if update is required. Is it necessary or just asking VFIO to use parent domain directly? > > Signed-off-by: Kenneth Lee <liguozhu@hisilicon.com> > --- > drivers/iommu/iommu.c | 28 +++++++++++++++++++++++++++- > include/linux/iommu.h | 2 ++ > 2 files changed, 29 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 63b37563db7e..a832aafe660d 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -54,6 +54,9 @@ struct iommu_group { > int id; > struct iommu_domain *default_domain; > struct iommu_domain *domain; > + atomic_t domain_shared_ref; /* Number of user of current domain. > + * The domain cannot be modified if ref > > 0 > + */ > }; > > struct group_device { > @@ -353,6 +356,7 @@ struct iommu_group *iommu_group_alloc(void) > return ERR_PTR(ret); > } > group->id = ret; > + atomic_set(&group->domain_shared_ref, 0); > > ret = kobject_init_and_add(&group->kobj, &iommu_group_ktype, > NULL, "%d", group->id); > @@ -482,6 +486,25 @@ int iommu_group_set_name(struct iommu_group > *group, const char *name) > } > EXPORT_SYMBOL_GPL(iommu_group_set_name); > > +struct iommu_domain *iommu_group_share_domain(struct > iommu_group *group) > +{ > + /* the domain can be shared only when the default domain is used > */ > + /* todo: more shareable check */ > + if (group->domain != group->default_domain) > + return ERR_PTR(-EINVAL); > + > + atomic_inc(&group->domain_shared_ref); > + return group->domain; > +} > +EXPORT_SYMBOL_GPL(iommu_group_share_domain); > + > +void iommu_group_unshare_domain(struct iommu_group *group) > +{ > + atomic_dec(&group->domain_shared_ref); > + WARN_ON(atomic_read(&group->domain_shared_ref) < 0); > +} > +EXPORT_SYMBOL_GPL(iommu_group_unshare_domain); > + > static int iommu_group_create_direct_mappings(struct iommu_group > *group, > struct device *dev) > { > @@ -1401,7 +1424,8 @@ static int __iommu_attach_group(struct > iommu_domain *domain, > { > int ret; > > - if (group->default_domain && group->domain != group- > >default_domain) > + if ((group->default_domain && group->domain != group- > >default_domain) || > + atomic_read(&group->domain_shared_ref) > 0) > return -EBUSY; > > ret = __iommu_group_for_each_dev(group, domain, > @@ -1438,6 +1462,8 @@ static void __iommu_detach_group(struct > iommu_domain *domain, > { > int ret; > > + WARN_ON(atomic_read(&group->domain_shared_ref) > 0); > + > if (!group->default_domain) { > __iommu_group_for_each_dev(group, domain, > iommu_group_do_detach_device); > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 19938ee6eb31..278d60e3ec39 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -349,6 +349,8 @@ extern int iommu_domain_get_attr(struct > iommu_domain *domain, enum iommu_attr, > void *data); > extern int iommu_domain_set_attr(struct iommu_domain *domain, enum > iommu_attr, > void *data); > +extern struct iommu_domain *iommu_group_share_domain(struct > iommu_group *group); > +extern void iommu_group_unshare_domain(struct iommu_group *group); > > /* Window handling function prototypes */ > extern int iommu_domain_window_enable(struct iommu_domain > *domain, u32 wnd_nr, > -- > 2.17.1
> From: Kenneth Lee > Sent: Thursday, August 2, 2018 12:16 PM > > On Thu, Aug 02, 2018 at 03:17:03AM +0000, Tian, Kevin wrote: > > > From: Kenneth Lee > > > Sent: Wednesday, August 1, 2018 6:22 PM > > > > > > From: Kenneth Lee <liguozhu@hisilicon.com> > > > > > > This patch add sharing interface for a iommu_group. The new interface: > > > > > > iommu_group_share_domain() > > > iommu_group_unshare_domain() > > > > > > can be used by some virtual iommu_group (such as iommu_group for > > > spimdev) > > > to share their parent's iommu_group. > > > > > > When the domain of the group is shared, it cannot be changed before > > > unshared. In the future, notification can be added if update is required. > > > > Is it necessary or just asking VFIO to use parent domain directly? > > > Even we add to VFIO, the iommu still need to be changed. We can move > the type1 > part to VFIO if we have agreement in RFC stage. We have similar consideration in IOMMU aware mdev series. Now we are inclined to avoid faked entity within IOMMU layer - leave to caller to figure out right physical entity for any IOMMU ops. That might be leveraged here too after we get a new version. Thanks Kevin
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 63b37563db7e..a832aafe660d 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -54,6 +54,9 @@ struct iommu_group { int id; struct iommu_domain *default_domain; struct iommu_domain *domain; + atomic_t domain_shared_ref; /* Number of user of current domain. + * The domain cannot be modified if ref > 0 + */ }; struct group_device { @@ -353,6 +356,7 @@ struct iommu_group *iommu_group_alloc(void) return ERR_PTR(ret); } group->id = ret; + atomic_set(&group->domain_shared_ref, 0); ret = kobject_init_and_add(&group->kobj, &iommu_group_ktype, NULL, "%d", group->id); @@ -482,6 +486,25 @@ int iommu_group_set_name(struct iommu_group *group, const char *name) } EXPORT_SYMBOL_GPL(iommu_group_set_name); +struct iommu_domain *iommu_group_share_domain(struct iommu_group *group) +{ + /* the domain can be shared only when the default domain is used */ + /* todo: more shareable check */ + if (group->domain != group->default_domain) + return ERR_PTR(-EINVAL); + + atomic_inc(&group->domain_shared_ref); + return group->domain; +} +EXPORT_SYMBOL_GPL(iommu_group_share_domain); + +void iommu_group_unshare_domain(struct iommu_group *group) +{ + atomic_dec(&group->domain_shared_ref); + WARN_ON(atomic_read(&group->domain_shared_ref) < 0); +} +EXPORT_SYMBOL_GPL(iommu_group_unshare_domain); + static int iommu_group_create_direct_mappings(struct iommu_group *group, struct device *dev) { @@ -1401,7 +1424,8 @@ static int __iommu_attach_group(struct iommu_domain *domain, { int ret; - if (group->default_domain && group->domain != group->default_domain) + if ((group->default_domain && group->domain != group->default_domain) || + atomic_read(&group->domain_shared_ref) > 0) return -EBUSY; ret = __iommu_group_for_each_dev(group, domain, @@ -1438,6 +1462,8 @@ static void __iommu_detach_group(struct iommu_domain *domain, { int ret; + WARN_ON(atomic_read(&group->domain_shared_ref) > 0); + if (!group->default_domain) { __iommu_group_for_each_dev(group, domain, iommu_group_do_detach_device); diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 19938ee6eb31..278d60e3ec39 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -349,6 +349,8 @@ extern int iommu_domain_get_attr(struct iommu_domain *domain, enum iommu_attr, void *data); extern int iommu_domain_set_attr(struct iommu_domain *domain, enum iommu_attr, void *data); +extern struct iommu_domain *iommu_group_share_domain(struct iommu_group *group); +extern void iommu_group_unshare_domain(struct iommu_group *group); /* Window handling function prototypes */ extern int iommu_domain_window_enable(struct iommu_domain *domain, u32 wnd_nr,