[PATCH kernel v9 31/32] vfio: powerpc/spapr: Support multiple groups in one container if possible

From: Alexey Kardashevskiy
Date: Sat Apr 25 2015 - 08:20:59 EST

At the moment only one group per container is supported.
POWER8 CPUs have more flexible design and allows naving 2 TCE tables per
IOMMU group so we can relax this limitation and support multiple groups
per container.

This adds TCE table descriptors to a container and uses iommu_table_group_ops
to create/set DMA windows on IOMMU groups so the same TCE tables will be
shared between several IOMMU groups.

Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
[aw: for the vfio related changes]
Acked-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
Changes:
v7:
* updated doc
---
Documentation/vfio.txt | 8 +-
drivers/vfio/vfio_iommu_spapr_tce.c | 268 ++++++++++++++++++++++++++----------
2 files changed, 199 insertions(+), 77 deletions(-)

diff --git a/Documentation/vfio.txt b/Documentation/vfio.txt
index 94328c8..7dcf2b5 100644
--- a/Documentation/vfio.txt
+++ b/Documentation/vfio.txt
@@ -289,10 +289,12 @@ PPC64 sPAPR implementation note

This implementation has some specifics:

-1) Only one IOMMU group per container is supported as an IOMMU group
-represents the minimal entity which isolation can be guaranteed for and
-groups are allocated statically, one per a Partitionable Endpoint (PE)
+1) On older systems (POWER7 with P5IOC2/IODA1) only one IOMMU group per
+container is supported as an IOMMU table is allocated at the boot time,
+one table per a IOMMU group which is a Partitionable Endpoint (PE)
(PE is often a PCI domain but not always).
+Newer systems (POWER8 with IODA2) have improved hardware design which allows
+to remove this limitation and have multiple IOMMU groups per a VFIO container.

2) The hardware supports so called DMA windows - the PCI address range
within which DMA transfer is allowed, any attempt to access address space
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index a7d6729..970e3a2 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -82,6 +82,11 @@ static void decrement_locked_vm(long npages)
* into DMA'ble space using the IOMMU
*/

+struct tce_iommu_group {
+ struct list_head next;
+ struct iommu_group *grp;
+};
+
/*
* The container descriptor supports only a single group per container.
* Required by the API as the container is not supplied with the IOMMU group
@@ -89,10 +94,11 @@ static void decrement_locked_vm(long npages)
*/
struct tce_container {
struct mutex lock;
- struct iommu_group *grp;
bool enabled;
unsigned long locked_pages;
bool v2;
+ struct iommu_table tables[IOMMU_TABLE_GROUP_MAX_TABLES];
+ struct list_head group_list;
};

static long tce_unregister_pages(struct tce_container *container,
@@ -154,20 +160,20 @@ static bool tce_page_is_contained(struct page *page, unsigned page_shift)
return (PAGE_SHIFT + compound_order(compound_head(page))) >= page_shift;
}

+static inline bool tce_groups_attached(struct tce_container *container)
+{
+ return !list_empty(&container->group_list);
+}
+
static struct iommu_table *spapr_tce_find_table(
struct tce_container *container,
phys_addr_t ioba)
{
long i;
struct iommu_table *ret = NULL;
- struct iommu_table_group *table_group;
-
- table_group = iommu_group_get_iommudata(container->grp);
- if (!table_group)
- return NULL;

for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
- struct iommu_table *tbl = &table_group->tables[i];
+ struct iommu_table *tbl = &container->tables[i];
unsigned long entry = ioba >> tbl->it_page_shift;
unsigned long start = tbl->it_offset;
unsigned long end = start + tbl->it_size;
@@ -186,9 +192,7 @@ static int tce_iommu_enable(struct tce_container *container)
int ret = 0;
unsigned long locked;
struct iommu_table_group *table_group;
-
- if (!container->grp)
- return -ENXIO;
+ struct tce_iommu_group *tcegrp;

if (!current->mm)
return -ESRCH; /* process exited */
@@ -225,7 +229,12 @@ static int tce_iommu_enable(struct tce_container *container)
* as there is no way to know how much we should increment
* the locked_vm counter.
*/
- table_group = iommu_group_get_iommudata(container->grp);
+ 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;

@@ -257,6 +266,48 @@ static void tce_iommu_disable(struct tce_container *container)
decrement_locked_vm(container->locked_pages);
}

+static long tce_iommu_create_table(struct iommu_table_group *table_group,
+ int num,
+ __u32 page_shift,
+ __u64 window_size,
+ __u32 levels,
+ struct iommu_table *tbl)
+{
+ long ret, table_size;
+
+ table_size = table_group->ops->get_table_size(page_shift, window_size,
+ levels);
+ if (!table_size)
+ return -EINVAL;
+
+ ret = try_increment_locked_vm(table_size >> PAGE_SHIFT);
+ if (ret)
+ return ret;
+
+ ret = table_group->ops->create_table(table_group, num,
+ page_shift, window_size, levels, tbl);
+
+ WARN_ON(!ret && !tbl->it_ops->free);
+ WARN_ON(!ret && (tbl->it_allocated_size != table_size));
+
+ if (ret)
+ decrement_locked_vm(table_size >> PAGE_SHIFT);
+
+ return ret;
+}
+
+static void tce_iommu_free_table(struct iommu_table *tbl)
+{
+ unsigned long pages = tbl->it_allocated_size >> PAGE_SHIFT;
+
+ if (!tbl->it_size)
+ return;
+
+ tbl->it_ops->free(tbl);
+ decrement_locked_vm(pages);
+ memset(tbl, 0, sizeof(*tbl));
+}
+
static void *tce_iommu_open(unsigned long arg)
{
struct tce_container *container;
@@ -271,19 +322,41 @@ static void *tce_iommu_open(unsigned long arg)
return ERR_PTR(-ENOMEM);

mutex_init(&container->lock);
+ INIT_LIST_HEAD_RCU(&container->group_list);
+
container->v2 = arg == VFIO_SPAPR_TCE_v2_IOMMU;

return container;
}

+static int tce_iommu_clear(struct tce_container *container,
+ struct iommu_table *tbl,
+ unsigned long entry, unsigned long pages);
+
static void tce_iommu_release(void *iommu_data)
{
struct tce_container *container = iommu_data;
+ struct iommu_table_group *table_group;
+ struct tce_iommu_group *tcegrp;
+ long i;

- WARN_ON(container->grp);
+ while (tce_groups_attached(container)) {
+ tcegrp = list_first_entry(&container->group_list,
+ struct tce_iommu_group, next);
+ table_group = iommu_group_get_iommudata(tcegrp->grp);
+ tce_iommu_detach_group(iommu_data, tcegrp->grp);
+ }

- if (container->grp)
- tce_iommu_detach_group(iommu_data, container->grp);
+ /*
+ * If VFIO created a table, it was not disposed
+ * by tce_iommu_detach_group() so do it now.
+ */
+ for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
+ struct iommu_table *tbl = &container->tables[i];
+
+ tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
+ tce_iommu_free_table(tbl);
+ }

tce_iommu_disable(container);
mutex_destroy(&container->lock);
@@ -509,12 +582,15 @@ static long tce_iommu_ioctl(void *iommu_data,

case VFIO_IOMMU_SPAPR_TCE_GET_INFO: {
struct vfio_iommu_spapr_tce_info info;
+ struct tce_iommu_group *tcegrp;
struct iommu_table_group *table_group;

- if (WARN_ON(!container->grp))
+ if (!tce_groups_attached(container))
return -ENXIO;

- table_group = iommu_group_get_iommudata(container->grp);
+ tcegrp = list_first_entry(&container->group_list,
+ struct tce_iommu_group, next);
+ table_group = iommu_group_get_iommudata(tcegrp->grp);

if (!table_group)
return -ENXIO;
@@ -707,12 +783,20 @@ static long tce_iommu_ioctl(void *iommu_data,
tce_iommu_disable(container);
mutex_unlock(&container->lock);
return 0;
- case VFIO_EEH_PE_OP:
- if (!container->grp)
- return -ENODEV;

- return vfio_spapr_iommu_eeh_ioctl(container->grp,
- cmd, arg);
+ case VFIO_EEH_PE_OP: {
+ struct tce_iommu_group *tcegrp;
+
+ ret = 0;
+ list_for_each_entry(tcegrp, &container->group_list, next) {
+ ret = vfio_spapr_iommu_eeh_ioctl(tcegrp->grp,
+ cmd, arg);
+ if (ret)
+ return ret;
+ }
+ return ret;
+ }
+
}

return -ENOTTY;
@@ -724,11 +808,14 @@ static void tce_iommu_release_ownership(struct tce_container *container,
int i;

for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
- struct iommu_table *tbl = &table_group->tables[i];
+ struct iommu_table *tbl = &container->tables[i];

tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
if (tbl->it_map)
iommu_release_ownership(tbl);
+
+ /* Reset the container's copy of the table descriptor */
+ memset(tbl, 0, sizeof(*tbl));
}
}

@@ -758,38 +845,56 @@ static int tce_iommu_take_ownership(struct iommu_table_group *table_group)
static int tce_iommu_attach_group(void *iommu_data,
struct iommu_group *iommu_group)
{
- int ret;
+ int ret, i;
struct tce_container *container = iommu_data;
struct iommu_table_group *table_group;
+ struct tce_iommu_group *tcegrp = NULL;
+ bool first_group = !tce_groups_attached(container);

mutex_lock(&container->lock);

/* pr_debug("tce_vfio: Attaching group #%u to iommu %p\n",
iommu_group_id(iommu_group), iommu_group); */
- if (container->grp) {
- pr_warn("tce_vfio: Only one group per IOMMU container is allowed, existing id=%d, attaching id=%d\n",
- iommu_group_id(container->grp),
- iommu_group_id(iommu_group));
- ret = -EBUSY;
- goto unlock_exit;
- }
-
- if (container->enabled) {
- pr_err("tce_vfio: attaching group #%u to enabled container\n",
- iommu_group_id(iommu_group));
- ret = -EBUSY;
- goto unlock_exit;
- }
-
table_group = iommu_group_get_iommudata(iommu_group);
- if (!table_group) {
- ret = -ENXIO;
+
+ if (!first_group && (!table_group->ops ||
+ !table_group->ops->take_ownership ||
+ !table_group->ops->release_ownership)) {
+ ret = -EBUSY;
+ goto unlock_exit;
+ }
+
+ /* Check if new group has the same iommu_ops (i.e. compatible) */
+ list_for_each_entry(tcegrp, &container->group_list, next) {
+ struct iommu_table_group *table_group_tmp;
+
+ if (tcegrp->grp == iommu_group) {
+ pr_warn("tce_vfio: Group %d is already attached\n",
+ iommu_group_id(iommu_group));
+ ret = -EBUSY;
+ goto unlock_exit;
+ }
+ table_group_tmp = iommu_group_get_iommudata(tcegrp->grp);
+ if (table_group_tmp->ops != table_group->ops) {
+ pr_warn("tce_vfio: Group %d is incompatible with group %d\n",
+ iommu_group_id(iommu_group),
+ iommu_group_id(tcegrp->grp));
+ ret = -EPERM;
+ goto unlock_exit;
+ }
+ }
+
+ tcegrp = kzalloc(sizeof(*tcegrp), GFP_KERNEL);
+ if (!tcegrp) {
+ ret = -ENOMEM;
goto unlock_exit;
}

if (!table_group->ops || !table_group->ops->take_ownership ||
!table_group->ops->release_ownership) {
ret = tce_iommu_take_ownership(table_group);
+ if (!ret)
+ container->tables[0] = table_group->tables[0];
} else if (!table_group->ops->create_table ||
!table_group->ops->set_window) {
WARN_ON_ONCE(1);
@@ -801,23 +906,46 @@ static int tce_iommu_attach_group(void *iommu_data,
* the pages that has been explicitly mapped into the iommu
*/
table_group->ops->take_ownership(table_group);
- ret = table_group->ops->create_table(table_group,
- 0, /* window number */
- IOMMU_PAGE_SHIFT_4K,
- table_group->tce32_size,
- 1, /* default levels */
- &table_group->tables[0]);
- if (!ret)
- ret = table_group->ops->set_window(table_group, 0,
- &table_group->tables[0]);
+ /*
+ * 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 (first_group && !container->tables[0].it_size) {
+ ret = tce_iommu_create_table(table_group,
+ 0, /* window number */
+ IOMMU_PAGE_SHIFT_4K,
+ table_group->tce32_size,
+ 1, /* default levels */
+ &container->tables[0]);
+ if (ret)
+ goto unlock_exit;
+ }
+
+ /* Set all windows to the new group */
+ for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
+ struct iommu_table *tbl = &container->tables[i];
+
+ if (!tbl->it_size)
+ continue;
+
+ /* Set the default window to a new group */
+ ret = table_group->ops->set_window(table_group, i, tbl);
+ if (ret)
+ break;
+ }
}

if (ret)
goto unlock_exit;

- container->grp = iommu_group;
+ tcegrp->grp = iommu_group;
+ list_add(&tcegrp->next, &container->group_list);

unlock_exit:
+ if (ret && tcegrp)
+ kfree(tcegrp);
+
mutex_unlock(&container->lock);

return ret;
@@ -828,25 +956,27 @@ static void tce_iommu_detach_group(void *iommu_data,
{
struct tce_container *container = iommu_data;
struct iommu_table_group *table_group;
+ struct tce_iommu_group *tcegrp;
long i;
+ bool found = false;

mutex_lock(&container->lock);
- if (iommu_group != container->grp) {
- pr_warn("tce_vfio: detaching group #%u, expected group is #%u\n",
- iommu_group_id(iommu_group),
- iommu_group_id(container->grp));
+
+ list_for_each_entry(tcegrp, &container->group_list, next) {
+ if (tcegrp->grp == iommu_group) {
+ found = true;
+ break;
+ }
+ }
+
+ if (!found) {
+ pr_warn("tce_vfio: detaching unattached group #%u\n",
+ iommu_group_id(iommu_group));
goto unlock_exit;
}

- if (container->enabled) {
- pr_warn("tce_vfio: detaching group #%u from enabled container, forcing disable\n",
- iommu_group_id(container->grp));
- tce_iommu_disable(container);
- }
-
- /* pr_debug("tce_vfio: detaching group #%u from iommu %p\n",
- iommu_group_id(iommu_group), iommu_group); */
- container->grp = NULL;
+ list_del(&tcegrp->next);
+ kfree(tcegrp);

table_group = iommu_group_get_iommudata(iommu_group);
BUG_ON(!table_group);
@@ -857,18 +987,8 @@ static void tce_iommu_detach_group(void *iommu_data,
else if (!table_group->ops->unset_window)
WARN_ON_ONCE(1);
else {
- for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
- struct iommu_table tbl = table_group->tables[i];
-
- if (!tbl.it_size)
- continue;
-
+ for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
table_group->ops->unset_window(table_group, i);
- tce_iommu_clear(container, &tbl,
- tbl.it_offset, tbl.it_size);
- if (tbl.it_ops->free)
- tbl.it_ops->free(&tbl);
- }

table_group->ops->release_ownership(table_group);
}
--
2.0.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/