On Tue, Nov 22, 2016 at 06:29:39PM +1100, Alexey Kardashevskiy wrote:
> On 22/11/16 13:50, David Gibson wrote:
> > On Fri, Nov 11, 2016 at 11:32:15PM +1100, Alexey Kardashevskiy wrote:
> >> As mentioned in the previous patch, we are going to allow the userspace
> >> to configure container in one memory context and pass container fd to
> >> another so we are postponing memory allocations accounted against
> >> the locked memory limit. The previous patch took care of it_userspace.
> >>
> >> At the moment we create the default DMA window when the first group is
> >> attached to a container; this is done for the userspace which is not
> >> DDW-aware but familiar with the SPAPR TCE IOMMU v2 in the part of memory
> >> pre-registration - such client expects the default DMA window to exist.
> >>
> >> This postpones the default DMA window allocation till first map/unmap
> >> request happens.
> >>
> >> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
> >> ---
> >> drivers/vfio/vfio_iommu_spapr_tce.c | 98 ++++++++++++++++++-------------------
> >> 1 file changed, 47 insertions(+), 51 deletions(-)
> >>
> >> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> >> index 442baac..1c02498 100644
> >> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> >> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> >> @@ -97,6 +97,7 @@ struct tce_container {
> >> struct mutex lock;
> >> bool enabled;
> >> bool v2;
> >> + bool def_window_pending;
> >> unsigned long locked_pages;
> >> struct iommu_table *tables[IOMMU_TABLE_GROUP_MAX_TABLES];
> >> struct list_head group_list;
> >> @@ -594,15 +595,6 @@ static long tce_iommu_create_table(struct tce_container *container,
> >> WARN_ON(!ret && !(*ptbl)->it_ops->free);
> >> WARN_ON(!ret && ((*ptbl)->it_allocated_size != table_size));
> >>
> >> - if (!ret && container->v2) {
> >> - ret = tce_iommu_userspace_view_alloc(*ptbl);
> >> - if (ret)
> >> - (*ptbl)->it_ops->free(*ptbl);
> >> - }
> >
> > Does this stuff for the user view belong in the previous patch?
>
> Yes it does, my mistake, will fix.
>
>
> >
> >> -
> >> - if (ret)
> >> - decrement_locked_vm(table_size >> PAGE_SHIFT);
> >> -
> >> return ret;
> >> }
> >>
> >> @@ -719,6 +711,29 @@ static long tce_iommu_remove_window(struct tce_container *container,
> >> return 0;
> >> }
> >>
> >> +static long tce_iommu_create_default_window(struct tce_container *container)
> >> +{
> >> + long ret;
> >> + __u64 start_addr = 0;
> >> + struct tce_iommu_group *tcegrp;
> >> + struct iommu_table_group *table_group;
> >> +
> >> + if (!tce_groups_attached(container))
> >> + return -ENODEV;
> >> +
> >> + tcegrp = list_first_entry(&container->group_list,
> >> + struct tce_iommu_group, next);
> >> + table_group = iommu_group_get_iommudata(tcegrp->grp);
> >> + if (!table_group)
> >> + return -ENODEV;
> >> +
> >> + ret = tce_iommu_create_window(container, IOMMU_PAGE_SHIFT_4K,
> >> + table_group->tce32_size, 1, &start_addr);
> >> + WARN_ON_ONCE(!ret && start_addr);
> >> +
> >> + return ret;
> >> +}
> >> +
> >> static long tce_iommu_ioctl(void *iommu_data,
> >> unsigned int cmd, unsigned long arg)
> >> {
> >> @@ -809,6 +824,13 @@ static long tce_iommu_ioctl(void *iommu_data,
> >> VFIO_DMA_MAP_FLAG_WRITE))
> >> return -EINVAL;
> >>
> >> + if (container->def_window_pending) {
> >> + ret = tce_iommu_create_default_window(container);
> >> + if (ret)
> >> + return ret;
> >> + container->def_window_pending = false;
> >
> > Would it make sense to clear (and maybe test) def_window_pending
> > within create_default_window()?
>
> Dunno, matter of taste I suppose. I'll move it there.
>
>
> >
> >> + }
> >> +
> >> num = tce_iommu_find_table(container, param.iova, &tbl);
> >> if (num < 0)
> >> return -ENXIO;
> >> @@ -872,6 +894,13 @@ static long tce_iommu_ioctl(void *iommu_data,
> >> if (param.flags)
> >> return -EINVAL;
> >>
> >> + if (container->def_window_pending) {
> >> + ret = tce_iommu_create_default_window(container);
> >> + if (ret)
> >> + return ret;
> >> + container->def_window_pending = false;
> >> + }
> >> +
> >> num = tce_iommu_find_table(container, param.iova, &tbl);
> >> if (num < 0)
> >> return -ENXIO;
> >> @@ -998,6 +1027,8 @@ static long tce_iommu_ioctl(void *iommu_data,
> >>
> >> mutex_lock(&container->lock);
> >>
> >> + container->def_window_pending = false;
> >
> > Uh.. why is it cleared here, without calling
> > tce_iommu_create_default_window() AFAICT?
>
>
> It is a branch which creates new window, if we do not have a default
> window, then it will be created as the result of this ioctl(), if there is
> a default window, then the flag should be false already.
Um.. it will create *a* window, but not necessarily the default one.
Consider this scenario:
1. Container is opened
2. A group is attached
3. Userspace, expecting the default window to be in place, creates a
second window
4. Mapping starts
Won't the above code mean that we create what userspace expected to be
the second window as the first window replacing the default one
instead?
>
>
>
>
> >
> >> ret = tce_iommu_create_window(container, create.page_shift,
> >> create.window_size, create.levels,
> >> &create.start_addr);
> >> @@ -1030,6 +1061,12 @@ static long tce_iommu_ioctl(void *iommu_data,
> >> if (remove.flags)
> >> return -EINVAL;
> >>
> >> + if (container->def_window_pending && !remove.start_addr) {
> >> + container->def_window_pending = false;
> >> + return 0;
> >> + }
> >> + container->def_window_pending = false;
> >> +
> >> mutex_lock(&container->lock);
> >>
> >> ret = tce_iommu_remove_window(container, remove.start_addr);
> >> @@ -1109,9 +1146,6 @@ static void tce_iommu_release_ownership_ddw(struct tce_container *container,
> >> static long tce_iommu_take_ownership_ddw(struct tce_container *container,
> >> struct iommu_table_group *table_group)
> >> {
> >> - long i, ret = 0;
> >> - struct iommu_table *tbl = NULL;
> >> -
> >> if (!table_group->ops->create_table || !table_group->ops->set_window ||
> >> !table_group->ops->release_ownership) {
> >> WARN_ON_ONCE(1);
> >> @@ -1120,47 +1154,9 @@ static long tce_iommu_take_ownership_ddw(struct tce_container *container,
> >>
> >> table_group->ops->take_ownership(table_group);
> >>
> >> - /*
> >> - * If it the first group attached, check if there is
> >> - * a default DMA window and create one if none as
> >> - * the userspace expects it to exist.
> >> - */
> >> - if (!tce_groups_attached(container) && !container->tables[0]) {
> >> - ret = tce_iommu_create_table(container,
> >> - table_group,
> >> - 0, /* window number */
> >> - IOMMU_PAGE_SHIFT_4K,
> >> - table_group->tce32_size,
> >> - 1, /* default levels */
> >> - &tbl);
> >> - if (ret)
> >> - goto release_exit;
> >> - else
> >> - container->tables[0] = tbl;
> >> - }
> >> -
> >> - /* Set all windows to the new group */
> >> - for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
> >> - tbl = container->tables[i];
> >> -
> >> - if (!tbl)
> >> - continue;
> >> -
> >> - /* Set the default window to a new group */
> >> - ret = table_group->ops->set_window(table_group, i, tbl);
> >
> > Uh... nothing in the new code seems to replace these set_window (and
> > unset_window) calls. What's up with that?
>
>
> tce_iommu_create_table() + set_window() is replaced with
> tce_iommu_create_default_window() which calls tce_iommu_create_window()
> which calls tce_iommu_create_table() + set_window().
>
> I'll split this patch into 2 patches, one with the change I just explained
> and one to postpone the default window creation.
Ah, right, I see.
>
>
> >
> >> - if (ret)
> >> - goto release_exit;
> >> - }
> >> + container->def_window_pending = true;
> >>
> >> return 0;
> >> -
> >> -release_exit:
> >> - for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
> >> - table_group->ops->unset_window(table_group, i);
> >> -
> >> - table_group->ops->release_ownership(table_group);
> >> -
> >> - return ret;
> >> }
> >>
> >> static int tce_iommu_attach_group(void *iommu_data,
> >
>
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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