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    SubjectRe: [PATCH kernel v11 33/34] vfio: powerpc/spapr: Register memory and define IOMMU v2
    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 <aik@ozlabs.ru>
    > [aw: for the vfio related changes]
    > Acked-by: Alex Williamson <alex.williamson@redhat.com>
    > ---
    > 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 "aik@ozlabs.ru"
    > @@ -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;

    Uh.. contrary to the commit message this doesn't enforce that the
    unregister is called on the exact same vaddr and size as was
    registered. Instead a call to unregister will unregister the first
    registered region that overlaps with the specified region.

    Also, ENOENT might be a better error code for this case (couldn't find
    a matching registered region) - EINVAL is rather overused.

    > +
    > + 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;

    I'm assuming that once any region is registered you can no longer add
    or remove groups from the container? That's fine but it might want a
    more prominent notice in the docs.

    > +
    > + 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);
    > +
    > + 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.

    You could choose not to create the 32-bit DMA window by default for v2
    containers. But I don't know if that would actually simplify anything.

    > + */
    > + 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 */

    --
    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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