Re: [PATCH v4 27/28] vfio: powerpc/spapr: Register memory

From: Alexey Kardashevskiy
Date: Thu Feb 19 2015 - 21:18:58 EST

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Just noticed - this patch should be split into two, they were squashed by mistake, my bad.

On 02/16/2015 09:06 PM, Alexey Kardashevskiy wrote:

The existing implementation accounts the whole DMA window in
the locked_vm counter which is going to be even worse with multiple
containers and huge DMA windows.

This introduces 2 ioctls to register/unregister DMA memory which
receive user space address and size of the memory region which
needs to be pinned/unpinned and counted in locked_vm.

If any memory region was registered, all subsequent DMA map requests
should address already pinned memory. If no memory was registered,
then the amount of memory required for a single default memory will be
accounted when the container is enabled and every map/unmap will pin/unpin
a page.

Dynamic DMA window and in-kernel acceleration will require memory to
be registered in order to work.

The accounting is done per VFIO container. When the support of
multiple groups per container is added, we will have accurate locked_vm
accounting.

Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
---
Changes:
v4:
* updated docs
* s/kzmalloc/vzalloc/
* in tce_pin_pages()/tce_unpin_pages() removed @vaddr, @size and
replaced offset with index
* renamed vfio_iommu_type_register_memory to vfio_iommu_spapr_register_memory
and removed duplicating vfio_iommu_spapr_register_memory
---
drivers/vfio/vfio_iommu_spapr_tce.c | 222 ++++++++++++++++++++++++------------
1 file changed, 148 insertions(+), 74 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 4ff8289..ee91d51 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -91,10 +91,16 @@ 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;
+ struct iommu_table tables[POWERPC_IOMMU_MAX_TABLES];
+ struct list_head group_list;
+};
+
+struct tce_iommu_group {
+ struct list_head next;
+ struct iommu_group *grp;
};

struct tce_memory {
@@ -300,19 +306,20 @@ static bool tce_page_is_contained(struct page *page, unsigned page_shift)
return false;
}

+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 powerpc_iommu *iommu = iommu_group_get_iommudata(container->grp);
-
- if (!iommu)
- return NULL;

for (i = 0; i < POWERPC_IOMMU_MAX_TABLES; ++i) {
- struct iommu_table *tbl = &iommu->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;
@@ -330,11 +337,8 @@ static int tce_iommu_enable(struct tce_container *container)
{
int ret = 0;
unsigned long locked;
- struct iommu_table *tbl;
struct powerpc_iommu *iommu;
-
- if (!container->grp)
- return -ENXIO;
+ struct tce_iommu_group *tcegrp;

if (!current->mm)
return -ESRCH; /* process exited */
@@ -368,12 +372,24 @@ static int tce_iommu_enable(struct tce_container *container)
* KVM agnostic.
*/
if (!tce_preregistered(container)) {
- iommu = 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);
+ iommu = iommu_group_get_iommudata(tcegrp->grp);
if (!iommu)
return -ENODEV;

- tbl = &iommu->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 (!iommu->tce32_size)
+ return -EPERM;
+
+ locked = iommu->tce32_size >> PAGE_SHIFT;
ret = try_increment_locked_vm(locked);
if (ret)
return ret;
@@ -386,6 +402,10 @@ static int tce_iommu_enable(struct tce_container *container)
return ret;
}

+static int tce_iommu_clear(struct tce_container *container,
+ struct iommu_table *tbl,
+ unsigned long entry, unsigned long pages);
+
static void tce_iommu_disable(struct tce_container *container)
{
if (!container->enabled)
@@ -414,6 +434,7 @@ 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);

return container;
}
@@ -427,16 +448,30 @@ static void tce_iommu_release(void *iommu_data)
struct tce_container *container = iommu_data;
struct iommu_table *tbl;
struct powerpc_iommu *iommu;
+ int i;
+ struct tce_iommu_group *tcegrp;
+ struct powerpc_iommu_ops *iommuops = NULL;

- WARN_ON(container->grp);
tce_iommu_disable(container);

- if (container->grp) {
- iommu = iommu_group_get_iommudata(container->grp);
- tbl = &iommu->tables[0];
- tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
- iommu->ops->free_table(tbl);
- tce_iommu_detach_group(iommu_data, container->grp);
+ /* Free tables */
+ if (iommuops) {
+ for (i = 0; i < POWERPC_IOMMU_MAX_TABLES; ++i) {
+ tbl = &container->tables[i];
+
+ tce_iommu_clear(container, tbl,
+ tbl->it_offset, tbl->it_size);
+
+ iommuops->free_table(tbl);
+ }
+ }
+
+ while (tce_groups_attached(container)) {
+ tcegrp = list_first_entry(&container->group_list,
+ struct tce_iommu_group, next);
+ iommu = iommu_group_get_iommudata(tcegrp->grp);
+ iommuops = iommu->ops;
+ tce_iommu_detach_group(iommu_data, tcegrp->grp);
}

tce_mem_unregister_all(container);
@@ -607,16 +642,17 @@ 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 powerpc_iommu *iommu;

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

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

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

minsz = offsetofend(struct vfio_iommu_spapr_tce_info,
@@ -628,9 +664,8 @@ 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 = iommu->tce32_start;
+ info.dma32_window_size = iommu->tce32_size;

if (copy_to_user((void __user *)arg, &info, minsz))
return -EFAULT;
@@ -779,12 +814,20 @@ 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;
@@ -793,34 +836,34 @@ static long tce_iommu_ioctl(void *iommu_data,
static int tce_iommu_attach_group(void *iommu_data,
struct iommu_group *iommu_group)
{
- int ret = 0;
+ int ret = 0, i;
struct tce_container *container = iommu_data;
- struct powerpc_iommu *iommu;
- struct iommu_table tbltmp = { 0 }, *tbl = &tbltmp;
+ struct powerpc_iommu *iommu = iommu_group_get_iommudata(iommu_group);
+ struct tce_iommu_group *tcegrp;
+ 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;
- }
+ list_for_each_entry(tcegrp, &container->group_list, next) {
+ struct powerpc_iommu *iommutmp;

- iommu = iommu_group_get_iommudata(iommu_group);
- if (WARN_ON_ONCE(!iommu)) {
- ret = -ENXIO;
- goto unlock_exit;
+ 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;
+ }
+ iommutmp = iommu_group_get_iommudata(tcegrp->grp);
+ if (iommutmp->ops != iommu->ops) {
+ pr_warn("tce_vfio: Group %d is incompatible with group %d\n",
+ iommu_group_id(iommu_group),
+ iommu_group_id(tcegrp->grp));
+ ret = -EBUSY;
+ goto unlock_exit;
+ }
}

/*
@@ -835,14 +878,48 @@ static int tce_iommu_attach_group(void *iommu_data,
goto unlock_exit;
}

- container->grp = iommu_group;
-
- /* Create the default window as only now we know the parameters */
- ret = iommu->ops->create_table(iommu, 0,
- IOMMU_PAGE_SHIFT_4K,
- ilog2(iommu->tce32_size), 1, tbl);
- if (!ret)
- ret = iommu->ops->set_window(iommu, 0, tbl);
+ /* Put the group to the list so tce_def_window_create() can succeed */
+ tcegrp = kzalloc(sizeof(*tcegrp), GFP_KERNEL);
+ tcegrp->grp = iommu_group;
+ list_add(&tcegrp->next, &container->group_list);
+
+ /*
+ * 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 < POWERPC_IOMMU_MAX_TABLES; ++i) {
+ if (!container->tables[i].it_size)
+ continue;
+
+ found = true;
+ break;
+ }
+ if (!found) {
+ struct iommu_table *tbl = &container->tables[0];
+
+ ret = iommu->ops->create_table(iommu, 0,
+ IOMMU_PAGE_SHIFT_4K,
+ ilog2(iommu->tce32_size), 1, tbl);
+ if (ret)
+ goto unlock_exit;
+ }
+ }
+
+ /* Set all windows to the new group */
+ for (i = 0; i < POWERPC_IOMMU_MAX_TABLES; ++i) {
+ struct iommu_table *tbl = &container->tables[i];
+
+ if (!tbl->it_size)
+ continue;
+
+ /* Set the default window to a new group */
+ ret = iommu->ops->set_window(iommu, i, tbl);
+ if (ret)
+ goto unlock_exit;
+ }

unlock_exit:
mutex_unlock(&container->lock);
@@ -855,24 +932,18 @@ static void tce_iommu_detach_group(void *iommu_data,
{
struct tce_container *container = iommu_data;
struct powerpc_iommu *iommu;
+ struct tce_iommu_group *tcegrp, *tcegrptmp;
long i;

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));
- } else {
- 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;
+ /* Detach windows from IOMMUs */
+ list_for_each_entry_safe(tcegrp, tcegrptmp, &container->group_list,
+ next) {
+ if (tcegrp->grp != iommu_group)
+ continue;

+ list_del(&tcegrp->next);
iommu = iommu_group_get_iommudata(iommu_group);
BUG_ON(!iommu);

@@ -882,6 +953,9 @@ static void tce_iommu_detach_group(void *iommu_data,
/* Kernel owns the device now, we can restore bypass */
if (iommu->ops && iommu->ops->set_ownership)
iommu->ops->set_ownership(iommu, false);
+
+ kfree(tcegrp);
+ break;
}
mutex_unlock(&container->lock);
}

--
Alexey
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Next message: Baoquan He: "Re: [PATCH] x86, boot: Allow 64bit EFI kernel to be loaded above 4G"
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In reply to: Alexey Kardashevskiy: "[PATCH v4 27/28] vfio: powerpc/spapr: Register memory"
Next in thread: Alexey Kardashevskiy: "[PATCH v4 26/28] vfio: powerpc/spapr: Rework an IOMMU group attach/detach"
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