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Subject[PATCH kernel v6 28/29] vfio: powerpc/spapr: Support multiple groups in one container if possible
Date
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@ozlabs.ru>
---
drivers/vfio/vfio_iommu_spapr_tce.c | 252 ++++++++++++++++++++++++------------
1 file changed, 170 insertions(+), 82 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 5e754b0..d94116b 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -91,11 +91,17 @@ static void decrement_locked_vm(long npages)
*/
struct tce_container {
struct mutex lock;
- struct iommu_group *grp;
bool enabled;
unsigned long locked_pages;
struct list_head mem_list;
bool v2;
+ struct iommu_table tables[IOMMU_TABLE_GROUP_MAX_TABLES];
+ struct list_head group_list;
+};
+
+struct tce_iommu_group {
+ struct list_head next;
+ struct iommu_group *grp;
};

struct tce_memory {
@@ -295,20 +301,20 @@ 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;
@@ -326,11 +332,8 @@ static int tce_iommu_enable(struct tce_container *container)
{
int ret = 0;
unsigned long locked;
- struct iommu_table *tbl;
struct iommu_table_group *table_group;
-
- if (!container->grp)
- return -ENXIO;
+ struct tce_iommu_group *tcegrp;

if (!current->mm)
return -ESRCH; /* process exited */
@@ -364,12 +367,24 @@ static int tce_iommu_enable(struct tce_container *container)
* KVM agnostic.
*/
if (!tce_preregistered(container)) {
- 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;

- tbl = &table_group->tables[0];
- locked = (tbl->it_size << tbl->it_page_shift) >> PAGE_SHIFT;
+ /*
+ * We do not allow enabling a group if no DMA-able memory was
+ * registered as there is no way to know how much we should
+ * increment the locked_vm counter.
+ */
+ if (!table_group->tce32_size)
+ return -EPERM;
+
+ locked = table_group->tce32_size >> PAGE_SHIFT;
ret = try_increment_locked_vm(locked);
if (ret)
return ret;
@@ -410,6 +425,7 @@ static void *tce_iommu_open(unsigned long arg)

mutex_init(&container->lock);
INIT_LIST_HEAD_RCU(&container->mem_list);
+ INIT_LIST_HEAD_RCU(&container->group_list);

container->v2 = arg == VFIO_SPAPR_TCE_v2_IOMMU;

@@ -423,11 +439,30 @@ static int tce_iommu_clear(struct tce_container *container,
static void tce_iommu_release(void *iommu_data)
{
struct tce_container *container = iommu_data;
+ struct iommu_table_group *table_group;
+ int i;
+ struct tce_iommu_group *tcegrp;

- 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);
+ /* Free tables */
+ for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
+ struct iommu_table *tbl = &container->tables[i];
+
+ if (!tbl->it_size)
+ continue;
+
+ tce_iommu_clear(container, tbl,
+ tbl->it_offset, tbl->it_size);
+
+ if (tbl->it_ops && tbl->it_ops->free)
+ tbl->it_ops->free(tbl);
+ }

tce_mem_unregister_all(container);
tce_iommu_disable(container);
@@ -588,16 +623,17 @@ static long tce_iommu_ioctl(void *iommu_data,

case VFIO_IOMMU_SPAPR_TCE_GET_INFO: {
struct vfio_iommu_spapr_tce_info info;
- struct iommu_table *tbl;
+ 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);

- tbl = &table_group->tables[0];
- if (WARN_ON_ONCE(!tbl))
+ if (!table_group)
return -ENXIO;

minsz = offsetofend(struct vfio_iommu_spapr_tce_info,
@@ -609,9 +645,8 @@ static long tce_iommu_ioctl(void *iommu_data,
if (info.argsz < minsz)
return -EINVAL;

- info.dma32_window_start = tbl->it_offset << tbl->it_page_shift;
- info.dma32_window_size = tbl->it_size << tbl->it_page_shift;
- info.flags = 0;
+ info.dma32_window_start = table_group->tce32_start;
+ info.dma32_window_size = table_group->tce32_size;

if (copy_to_user((void __user *)arg, &info, minsz))
return -EFAULT;
@@ -781,12 +816,20 @@ 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;
@@ -795,63 +838,111 @@ static long tce_iommu_ioctl(void *iommu_data,
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->set_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->set_ownership) {
ret = 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);
ret = -EFAULT;
} else {
- /*
- * Disable iommu bypass, otherwise the user can DMA to all of
- * our physical memory via the bypass window instead of just
- * the pages that has been explicitly mapped into the iommu
- */
- struct iommu_table tbltmp = { 0 }, *tbl = &tbltmp;
-
table_group->ops->set_ownership(table_group, true);
- ret = table_group->ops->create_table(table_group, 0,
- IOMMU_PAGE_SHIFT_4K,
- table_group->tce32_size, 1, tbl);
- if (!ret)
- ret = table_group->ops->set_window(table_group, 0, tbl);
+ /*
+ * If it the first group attached, check if there is any window
+ * created and create one if none.
+ */
+ if (first_group) {
+ bool found = false;
+
+ for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
+ if (!container->tables[i].it_size)
+ continue;
+
+ found = true;
+ break;
+ }
+ if (!found) {
+ struct iommu_table *tbl = &container->tables[0];
+
+ ret = table_group->ops->create_table(
+ table_group, 0,
+ IOMMU_PAGE_SHIFT_4K,
+ table_group->tce32_size, 1,
+ tbl);
+ 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;
@@ -862,25 +953,27 @@ 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, *tcetmp;
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_safe(tcegrp, tcetmp, &container->group_list, next) {
+ if (tcegrp->grp != iommu_group)
+ continue;
+ 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);
@@ -888,7 +981,7 @@ static void tce_iommu_detach_group(void *iommu_data,
/* Kernel owns the device now, we can restore bypass */
if (!table_group->ops || !table_group->ops->set_ownership) {
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];

if (!tbl->it_size)
continue;
@@ -897,20 +990,15 @@ static void tce_iommu_detach_group(void *iommu_data,
goto unlock_exit;
tce_iommu_clear(container, tbl,
tbl->it_offset, tbl->it_size);
+
+ memset(tbl, 0, sizeof(*tbl));
}
iommu_release_ownership(table_group);
} 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];
-
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->set_ownership(table_group, false);
--
2.0.0


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