Subject: Re: [PATCH kernel v11 33/34] vfio: powerpc/spapr: Register memory and define IOMMU v2

From: Gavin Shan <[email-masked]>
Date: Fri, 5 Jun 2015 10:01:48 +1000

On Fri, May 29, 2015 at 06:44:57PM +1000, Alexey Kardashevskiy wrote:
>The existing implementation accounts the whole DMA window in
>the locked_vm counter. This is going to be worse with multiple
>containers and huge DMA windows. Also, real-time accounting would requite
>additional tracking of accounted pages due to the page size difference -
>IOMMU uses 4K pages and system uses 4K or 64K pages.
>
>Another issue is that actual pages pinning/unpinning happens on every
>DMA map/unmap request. This does not affect the performance much now as
>we spend way too much time now on switching context between
>guest/userspace/host but this will start to matter when we add in-kernel
>DMA map/unmap acceleration.
>
>This introduces a new IOMMU type for SPAPR - VFIO_SPAPR_TCE_v2_IOMMU.
>New IOMMU deprecates VFIO_IOMMU_ENABLE/VFIO_IOMMU_DISABLE and introduces
>2 new ioctls to register/unregister DMA memory -
>VFIO_IOMMU_SPAPR_REGISTER_MEMORY and VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY -
>which receive user space address and size of a memory region which
>needs to be pinned/unpinned and counted in locked_vm.
>New IOMMU splits physical pages pinning and TCE table update
>into 2 different operations. It requires:
>1) guest pages to be registered first
>2) consequent map/unmap requests to work only with pre-registered memory.
>For the default single window case this means that the entire guest
>(instead of 2GB) needs to be pinned before using VFIO.
>When a huge DMA window is added, no additional pinning will be
>required, otherwise it would be guest RAM + 2GB.
>
>The new memory registration ioctls are not supported by
>VFIO_SPAPR_TCE_IOMMU. Dynamic DMA window and in-kernel acceleration
>will require memory to be preregistered in order to work.
>
>The accounting is done per the user process.
>
>This advertises v2 SPAPR TCE IOMMU and restricts what the userspace
>can do with v1 or v2 IOMMUs.
>
>In order to support memory pre-registration, we need a way to track
>the use of every registered memory region and only allow unregistration
>if a region is not in use anymore. So we need a way to tell from what
>region the just cleared TCE was from.
>
>This adds a userspace view of the TCE table into iommu_table struct.
>It contains userspace address, one per TCE entry. The table is only
>allocated when the ownership over an IOMMU group is taken which means
>it is only used from outside of the powernv code (such as VFIO).
>
>Signed-off-by: Alexey Kardashevskiy <[email-masked]>
>[aw: for the vfio related changes]
>Acked-by: Alex Williamson <[email-masked]>
>---
>Changes:
>v11:
>* mm_iommu_put() does not return a code so this does not check it
>* moved "v2" in tce_container to pack the struct
>
>v10:
>* moved it_userspace allocation to vfio_iommu_spapr_tce as it VFIO
>specific thing
>* squashed "powerpc/iommu: Add userspace view of TCE table" into this as
>it is
>a part of IOMMU v2
>* s/tce_iommu_use_page_v2/tce_iommu_prereg_ua_to_hpa/
>* fixed some function names to have "tce_iommu_" in the beginning rather
>just "tce_"
>* as mm_iommu_mapped_inc() can now fail, check for the return code
>
>v9:
>* s/tce_get_hva_cached/tce_iommu_use_page_v2/
>
>v7:
>* now memory is registered per mm (i.e. process)
>* moved memory registration code to powerpc/mmu
>* merged "vfio: powerpc/spapr: Define v2 IOMMU" into this
>* limited new ioctls to v2 IOMMU
>* updated doc
>* unsupported ioclts return -ENOTTY instead of -EPERM
>
>v6:
>* tce_get_hva_cached() returns hva via a pointer
>
>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
>---
> Documentation/vfio.txt              |  31 ++-
> arch/powerpc/include/asm/iommu.h    |   6 +
> drivers/vfio/vfio_iommu_spapr_tce.c | 512 ++++++++++++++++++++++++++++++------
> include/uapi/linux/vfio.h           |  27 ++
> 4 files changed, 487 insertions(+), 89 deletions(-)
>
>diff --git a/Documentation/vfio.txt b/Documentation/vfio.txt
>index 96978ec..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
>@@ -427,6 +429,29 @@ The code flow from the example above should be slightly changed:
>
> 	....
>
>+5) There is v2 of SPAPR TCE IOMMU. It deprecates VFIO_IOMMU_ENABLE/
>+VFIO_IOMMU_DISABLE and implements 2 new ioctls:
>+VFIO_IOMMU_SPAPR_REGISTER_MEMORY and VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY
>+(which are unsupported in v1 IOMMU).
>+
>+PPC64 paravirtualized guests generate a lot of map/unmap requests,
>+and the handling of those includes pinning/unpinning pages and updating
>+mm::locked_vm counter to make sure we do not exceed the rlimit.
>+The v2 IOMMU splits accounting and pinning into separate operations:
>+
>+- VFIO_IOMMU_SPAPR_REGISTER_MEMORY/VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY ioctls
>+receive a user space address and size of the block to be pinned.
>+Bisecting is not supported and VFIO_IOMMU_UNREGISTER_MEMORY is expected to
>+be called with the exact address and size used for registering
>+the memory block. The userspace is not expected to call these often.
>+The ranges are stored in a linked list in a VFIO container.
>+
>+- VFIO_IOMMU_MAP_DMA/VFIO_IOMMU_UNMAP_DMA ioctls only update the actual
>+IOMMU table and do not do pinning; instead these check that the userspace
>+address is from pre-registered range.
>+
>+This separation helps in optimizing DMA for guests.
>+
> -------------------------------------------------------------------------------
>
> [1] VFIO was originally an acronym for "Virtual Function I/O" in its
>diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
>index 9d37492..f9957eb 100644
>--- a/arch/powerpc/include/asm/iommu.h
>+++ b/arch/powerpc/include/asm/iommu.h
>@@ -112,9 +112,15 @@ struct iommu_table {
> 	unsigned long *it_map;       /* A simple allocation bitmap for now */
> 	unsigned long  it_page_shift;/* table iommu page size */
> 	struct list_head it_group_list;/* List of iommu_table_group_link */
>+	unsigned long *it_userspace; /* userspace view of the table */
> 	struct iommu_table_ops *it_ops;
> };
>
>+#define IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry) \
>+		((tbl)->it_userspace ? \
>+			&((tbl)->it_userspace[(entry) - (tbl)->it_offset]) : \
>+			NULL)
>+
> /* Pure 2^n version of get_order */
> static inline __attribute_const__
> int get_iommu_order(unsigned long size, struct iommu_table *tbl)
>diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
>index 7a84110..cadd9f8 100644
>--- a/drivers/vfio/vfio_iommu_spapr_tce.c
>+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
>@@ -19,8 +19,10 @@
> #include <linux/uaccess.h>
> #include <linux/err.h>
> #include <linux/vfio.h>
>+#include <linux/vmalloc.h>
> #include <asm/iommu.h>
> #include <asm/tce.h>
>+#include <asm/mmu_context.h>
>
> #define DRIVER_VERSION  "0.1"
> #define DRIVER_AUTHOR   "[email-masked]"
>@@ -81,6 +83,11 @@ 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
>@@ -88,11 +95,84 @@ static void decrement_locked_vm(long npages)
>  */
> struct tce_container {
> 	struct mutex lock;
>-	struct iommu_group *grp;
> 	bool enabled;
>+	bool v2;
> 	unsigned long locked_pages;
>+	struct iommu_table *tables[IOMMU_TABLE_GROUP_MAX_TABLES];
>+	struct list_head group_list;
> };
>
>+static long tce_iommu_unregister_pages(struct tce_container *container,
>+		__u64 vaddr, __u64 size)
>+{
>+	struct mm_iommu_table_group_mem_t *mem;
>+
>+	if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK))
>+		return -EINVAL;
>+
>+	mem = mm_iommu_lookup(vaddr, size >> PAGE_SHIFT);
>+	if (!mem)
>+		return -EINVAL;
>+
>+	return mm_iommu_put(mem);
>+}
>+
>+static long tce_iommu_register_pages(struct tce_container *container,
>+		__u64 vaddr, __u64 size)
>+{
>+	long ret = 0;
>+	struct mm_iommu_table_group_mem_t *mem = NULL;
>+	unsigned long entries = size >> PAGE_SHIFT;
>+
>+	if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK) ||
>+			((vaddr + size) < vaddr))
>+		return -EINVAL;
>+
>+	ret = mm_iommu_get(vaddr, entries, &mem);
>+	if (ret)
>+		return ret;
>+
>+	container->enabled = true;
>+
>+	return 0;
>+}
>+
>+static long tce_iommu_userspace_view_alloc(struct iommu_table *tbl)
>+{
>+	unsigned long cb = _ALIGN_UP(sizeof(tbl->it_userspace[0]) *
>+			tbl->it_size, PAGE_SIZE);
>+	unsigned long *uas;
>+	long ret;
>+
>+	BUG_ON(tbl->it_userspace);
>+
>+	ret = try_increment_locked_vm(cb >> PAGE_SHIFT);
>+	if (ret)
>+		return ret;
>+
>+	uas = vzalloc(cb);
>+	if (!uas) {
>+		decrement_locked_vm(cb >> PAGE_SHIFT);
>+		return -ENOMEM;
>+	}
>+	tbl->it_userspace = uas;
>+
>+	return 0;
>+}
>+
>+static void tce_iommu_userspace_view_free(struct iommu_table *tbl)
>+{
>+	unsigned long cb = _ALIGN_UP(sizeof(tbl->it_userspace[0]) *
>+			tbl->it_size, PAGE_SIZE);
>+
>+	if (!tbl->it_userspace)
>+		return;
>+
>+	vfree(tbl->it_userspace);
>+	tbl->it_userspace = NULL;
>+	decrement_locked_vm(cb >> PAGE_SHIFT);
>+}
>+
> static bool tce_page_is_contained(struct page *page, unsigned page_shift)
> {
> 	/*
>@@ -103,18 +183,18 @@ 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 long tce_iommu_find_table(struct tce_container *container,
> 		phys_addr_t ioba, struct iommu_table **ptbl)
> {
> 	long i;
>-	struct iommu_table_group *table_group;
>-
>-	table_group = iommu_group_get_iommudata(container->grp);
>-	if (!table_group)
>-		return -1;
>
> 	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) {
> 			unsigned long entry = ioba >> tbl->it_page_shift;
>@@ -136,9 +216,7 @@ 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 */
>@@ -175,7 +253,12 @@ 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;
>
>@@ -211,7 +294,7 @@ static void *tce_iommu_open(unsigned long arg)
> {
> 	struct tce_container *container;
>
>-	if (arg != VFIO_SPAPR_TCE_IOMMU) {
>+	if ((arg != VFIO_SPAPR_TCE_IOMMU) && (arg != VFIO_SPAPR_TCE_v2_IOMMU)) {
> 		pr_err("tce_vfio: Wrong IOMMU type\n");
> 		return ERR_PTR(-EINVAL);
> 	}
>@@ -221,18 +304,45 @@ 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_free_table(struct iommu_table *tbl);
>+
> 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];
>+
>+		if (!tbl)
>+			continue;
>+
>+		tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
>+		tce_iommu_free_table(tbl);
>+	}
>
> 	tce_iommu_disable(container);
> 	mutex_destroy(&container->lock);
>@@ -249,6 +359,47 @@ static void tce_iommu_unuse_page(struct tce_container *container,
> 	put_page(page);
> }
>
>+static int tce_iommu_prereg_ua_to_hpa(unsigned long tce, unsigned long size,
>+		unsigned long *phpa, struct mm_iommu_table_group_mem_t **pmem)
>+{
>+	long ret = 0;
>+	struct mm_iommu_table_group_mem_t *mem;
>+
>+	mem = mm_iommu_lookup(tce, size);
>+	if (!mem)
>+		return -EINVAL;
>+
>+	ret = mm_iommu_ua_to_hpa(mem, tce, phpa);
>+	if (ret)
>+		return -EINVAL;
>+
>+	*pmem = mem;
>+
>+	return 0;
>+}
>+
>+static void tce_iommu_unuse_page_v2(struct iommu_table *tbl,
>+		unsigned long entry)
>+{
>+	struct mm_iommu_table_group_mem_t *mem = NULL;
>+	int ret;
>+	unsigned long hpa = 0;
>+	unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
>+
>+	if (!pua || !current || !current->mm)
>+		return;
>+
>+	ret = tce_iommu_prereg_ua_to_hpa(*pua, IOMMU_PAGE_SIZE(tbl),
>+			&hpa, &mem);
>+	if (ret)
>+		pr_debug("%s: tce %lx at #%lx was not cached, ret=%d\n",
>+				__func__, *pua, entry, ret);
>+	if (mem)
>+		mm_iommu_mapped_dec(mem);
>+
>+	*pua = 0;
>+}
>+
> static int tce_iommu_clear(struct tce_container *container,
> 		struct iommu_table *tbl,
> 		unsigned long entry, unsigned long pages)
>@@ -267,6 +418,11 @@ static int tce_iommu_clear(struct tce_container *container,
> 		if (direction == DMA_NONE)
> 			continue;
>
>+		if (container->v2) {
>+			tce_iommu_unuse_page_v2(tbl, entry);
>+			continue;
>+		}
>+
> 		tce_iommu_unuse_page(container, oldhpa);
> 	}
>
>@@ -333,6 +489,64 @@ static long tce_iommu_build(struct tce_container *container,
> 	return ret;
> }
>
>+static long tce_iommu_build_v2(struct tce_container *container,
>+		struct iommu_table *tbl,
>+		unsigned long entry, unsigned long tce, unsigned long pages,
>+		enum dma_data_direction direction)
>+{
>+	long i, ret = 0;
>+	struct page *page;
>+	unsigned long hpa;
>+	enum dma_data_direction dirtmp;
>+
>+	for (i = 0; i < pages; ++i) {
>+		struct mm_iommu_table_group_mem_t *mem = NULL;
>+		unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl,
>+				entry + i);
>+
>+		ret = tce_iommu_prereg_ua_to_hpa(tce, IOMMU_PAGE_SIZE(tbl),
>+				&hpa, &mem);
>+		if (ret)
>+			break;
>+
>+		page = pfn_to_page(hpa >> PAGE_SHIFT);
>+		if (!tce_page_is_contained(page, tbl->it_page_shift)) {
>+			ret = -EPERM;
>+			break;
>+		}
>+
>+		/* Preserve offset within IOMMU page */
>+		hpa |= tce & IOMMU_PAGE_MASK(tbl) & ~PAGE_MASK;
>+		dirtmp = direction;
>+
>+		/* The registered region is being unregistered */
>+		if (mm_iommu_mapped_inc(mem))
>+			break;
>+
>+		ret = iommu_tce_xchg(tbl, entry + i, &hpa, &dirtmp);
>+		if (ret) {
>+			/* dirtmp cannot be DMA_NONE here */
>+			tce_iommu_unuse_page_v2(tbl, entry + i);
>+			pr_err("iommu_tce: %s failed ioba=%lx, tce=%lx, ret=%ld\n",
>+					__func__, entry << tbl->it_page_shift,
>+					tce, ret);
>+			break;
>+		}
>+
>+		if (dirtmp != DMA_NONE)
>+			tce_iommu_unuse_page_v2(tbl, entry + i);
>+
>+		*pua = tce;
>+
>+		tce += IOMMU_PAGE_SIZE(tbl);
>+	}
>+
>+	if (ret)
>+		tce_iommu_clear(container, tbl, entry, i);
>+
>+	return ret;
>+}
>+
> static long tce_iommu_create_table(struct tce_container *container,
> 			struct iommu_table_group *table_group,
> 			int num,
>@@ -358,6 +572,12 @@ 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);
>+	}
>+
> 	if (ret)
> 		decrement_locked_vm(table_size >> PAGE_SHIFT);
>
>@@ -368,6 +588,7 @@ static void tce_iommu_free_table(struct iommu_table *tbl)
> {
> 	unsigned long pages = tbl->it_allocated_size >> PAGE_SHIFT;
>
>+	tce_iommu_userspace_view_free(tbl);
> 	tbl->it_ops->free(tbl);
> 	decrement_locked_vm(pages);
> }
>@@ -383,6 +604,7 @@ static long tce_iommu_ioctl(void *iommu_data,
> 	case VFIO_CHECK_EXTENSION:
> 		switch (arg) {
> 		case VFIO_SPAPR_TCE_IOMMU:
>+		case VFIO_SPAPR_TCE_v2_IOMMU:
> 			ret = 1;
> 			break;
> 		default:
>@@ -394,12 +616,15 @@ 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;
>@@ -468,11 +693,18 @@ static long tce_iommu_ioctl(void *iommu_data,
> 		if (ret)
> 			return ret;
>
>-		ret = tce_iommu_build(container, tbl,
>-				param.iova >> tbl->it_page_shift,
>-				param.vaddr,
>-				param.size >> tbl->it_page_shift,
>-				direction);
>+		if (container->v2)
>+			ret = tce_iommu_build_v2(container, tbl,
>+					param.iova >> tbl->it_page_shift,
>+					param.vaddr,
>+					param.size >> tbl->it_page_shift,
>+					direction);
>+		else
>+			ret = tce_iommu_build(container, tbl,
>+					param.iova >> tbl->it_page_shift,
>+					param.vaddr,
>+					param.size >> tbl->it_page_shift,
>+					direction);
>
> 		iommu_flush_tce(tbl);
>
>@@ -518,7 +750,61 @@ static long tce_iommu_ioctl(void *iommu_data,
>
> 		return ret;
> 	}
>+	case VFIO_IOMMU_SPAPR_REGISTER_MEMORY: {
>+		struct vfio_iommu_spapr_register_memory param;
>+
>+		if (!container->v2)
>+			break;
>+
>+		minsz = offsetofend(struct vfio_iommu_spapr_register_memory,
>+				size);
>+
>+		if (copy_from_user(&param, (void __user *)arg, minsz))
>+			return -EFAULT;
>+
>+		if (param.argsz < minsz)
>+			return -EINVAL;
>+
>+		/* No flag is supported now */
>+		if (param.flags)
>+			return -EINVAL;
>+
>+		mutex_lock(&container->lock);
>+		ret = tce_iommu_register_pages(container, param.vaddr,
>+				param.size);
>+		mutex_unlock(&container->lock);
>+
>+		return ret;
>+	}
>+	case VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY: {
>+		struct vfio_iommu_spapr_register_memory param;
>+
>+		if (!container->v2)
>+			break;
>+
>+		minsz = offsetofend(struct vfio_iommu_spapr_register_memory,
>+				size);
>+
>+		if (copy_from_user(&param, (void __user *)arg, minsz))
>+			return -EFAULT;
>+
>+		if (param.argsz < minsz)
>+			return -EINVAL;
>+
>+		/* No flag is supported now */
>+		if (param.flags)
>+			return -EINVAL;
>+
>+		mutex_lock(&container->lock);
>+		ret = tce_iommu_unregister_pages(container, param.vaddr, param.size);
>+		mutex_unlock(&container->lock);

Complain from checkpatch.pl:

WARNING: line over 80 characters
#600: FILE: drivers/vfio/vfio_iommu_spapr_tce.c:799:
+		ret = tce_iommu_unregister_pages(container, param.vaddr, param.size);

Thanks,
Gavin

>+
>+		return ret;
>+	}
> 	case VFIO_IOMMU_ENABLE:
>+		if (container->v2)
>+			break;
>+
> 		mutex_lock(&container->lock);
> 		ret = tce_iommu_enable(container);
> 		mutex_unlock(&container->lock);
>@@ -526,16 +812,27 @@ static long tce_iommu_ioctl(void *iommu_data,
>
>
> 	case VFIO_IOMMU_DISABLE:
>+		if (container->v2)
>+			break;
>+
> 		mutex_lock(&container->lock);
> 		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;
>@@ -547,14 +844,17 @@ 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];
>
> 		if (!tbl)
> 			continue;
>
> 		tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
>+		tce_iommu_userspace_view_free(tbl);
> 		if (tbl->it_map)
> 			iommu_release_ownership(tbl);
>+
>+		container->tables[i] = NULL;
> 	}
> }
>
>@@ -569,7 +869,10 @@ static int tce_iommu_take_ownership(struct tce_container *container,
> 		if (!tbl || !tbl->it_map)
> 			continue;
>
>-		rc = iommu_take_ownership(tbl);
>+		rc = tce_iommu_userspace_view_alloc(tbl);
>+		if (!rc)
>+			rc = iommu_take_ownership(tbl);
>+
> 		if (rc) {
> 			for (j = 0; j < i; ++j)
> 				iommu_release_ownership(
>@@ -579,6 +882,9 @@ static int tce_iommu_take_ownership(struct tce_container *container,
> 		}
> 	}
>
>+	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
>+		container->tables[i] = table_group->tables[i];
>+
> 	return 0;
> }
>
>@@ -592,18 +898,8 @@ static void tce_iommu_release_ownership_ddw(struct tce_container *container,
> 		return;
> 	}
>
>-	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
>-		/* Store table pointer as unset_window resets it */
>-		struct iommu_table *tbl = table_group->tables[i];
>-
>-		if (!tbl)
>-			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);
>-		tce_iommu_free_table(tbl);
>-	}
>
> 	table_group->ops->release_ownership(table_group);
> }
>@@ -611,7 +907,7 @@ 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 ret;
>+	long i, ret = 0;
> 	struct iommu_table *tbl = NULL;
>
> 	if (!table_group->ops->create_table || !table_group->ops->set_window ||
>@@ -622,23 +918,45 @@ static long tce_iommu_take_ownership_ddw(struct tce_container *container,
>
> 	table_group->ops->take_ownership(table_group);
>
>-	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) {
>-		ret = table_group->ops->set_window(table_group, 0, tbl);
>+	/*
>+	 * 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)
>-			tce_iommu_free_table(tbl);
>+			goto release_exit;
> 		else
>-			table_group->tables[0] = tbl;
>+			container->tables[0] = tbl;
> 	}
>
>-	if (ret)
>-		table_group->ops->release_ownership(table_group);
>+	/* 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);
>+		if (ret)
>+			goto release_exit;
>+	}
>+
>+	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;
> }
>@@ -649,29 +967,44 @@ static int tce_iommu_attach_group(void *iommu_data,
> 	int ret;
> 	struct tce_container *container = iommu_data;
> 	struct iommu_table_group *table_group;
>+	struct tce_iommu_group *tcegrp = NULL;
>
> 	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 (tce_groups_attached(container) && (!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;
> 	}
>
>@@ -681,10 +1014,15 @@ static int tce_iommu_attach_group(void *iommu_data,
> 	else
> 		ret = tce_iommu_take_ownership_ddw(container, table_group);
>
>-	if (!ret)
>-		container->grp = iommu_group;
>+	if (!ret) {
>+		tcegrp->grp = iommu_group;
>+		list_add(&tcegrp->next, &container->group_list);
>+	}
>
> unlock_exit:
>+	if (ret && tcegrp)
>+		kfree(tcegrp);
>+
> 	mutex_unlock(&container->lock);
>
> 	return ret;
>@@ -695,24 +1033,26 @@ static void tce_iommu_detach_group(void *iommu_data,
> {
> 	struct tce_container *container = iommu_data;
> 	struct iommu_table_group *table_group;
>+	bool found = false;
>+	struct tce_iommu_group *tcegrp;
>
> 	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);
>diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
>index b57b750..8fdcfb9 100644
>--- a/include/uapi/linux/vfio.h
>+++ b/include/uapi/linux/vfio.h
>@@ -36,6 +36,8 @@
> /* Two-stage IOMMU */
> #define VFIO_TYPE1_NESTING_IOMMU	6	/* Implies v2 */
>
>+#define VFIO_SPAPR_TCE_v2_IOMMU		7
>+
> /*
>  * The IOCTL interface is designed for extensibility by embedding the
>  * structure length (argsz) and flags into structures passed between
>@@ -495,6 +497,31 @@ struct vfio_eeh_pe_op {
>
> #define VFIO_EEH_PE_OP			_IO(VFIO_TYPE, VFIO_BASE + 21)
>
>+/**
>+ * VFIO_IOMMU_SPAPR_REGISTER_MEMORY - _IOW(VFIO_TYPE, VFIO_BASE + 17, struct vfio_iommu_spapr_register_memory)
>+ *
>+ * Registers user space memory where DMA is allowed. It pins
>+ * user pages and does the locked memory accounting so
>+ * subsequent VFIO_IOMMU_MAP_DMA/VFIO_IOMMU_UNMAP_DMA calls
>+ * get faster.
>+ */
>+struct vfio_iommu_spapr_register_memory {
>+	__u32	argsz;
>+	__u32	flags;
>+	__u64	vaddr;				/* Process virtual address */
>+	__u64	size;				/* Size of mapping (bytes) */
>+};
>+#define VFIO_IOMMU_SPAPR_REGISTER_MEMORY	_IO(VFIO_TYPE, VFIO_BASE + 17)
>+
>+/**
>+ * VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY - _IOW(VFIO_TYPE, VFIO_BASE + 18, struct vfio_iommu_spapr_register_memory)
>+ *
>+ * Unregisters user space memory registered with
>+ * VFIO_IOMMU_SPAPR_REGISTER_MEMORY.
>+ * Uses vfio_iommu_spapr_register_memory for parameters.
>+ */
>+#define VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY	_IO(VFIO_TYPE, VFIO_BASE + 18)
>+
> /* ***************************************************************** */
>
> #endif /* _UAPIVFIO_H */
>-- 
>2.4.0.rc3.8.gfb3e7d5
>