[v2,1/3] memory: introduce IOMMUNotifier and its caps

IOMMU Notifier list is used for notifying IO address mapping changes.
Currently VFIO is the only user.

However it is possible that future consumer like vhost would like to
only listen to part of its notifications (e.g., cache invalidations).

This patch introduced IOMMUNotifier and IOMMUNotfierCap bits for a finer
grained control of it.

IOMMUNotifier contains a bitfield for the notify consumer describing
what kind of notification it is interested in. Currently two kinds of
notifications are defined:

- IOMMU_NOTIFIER_CHANGE:       for entry changes (additions)
- IOMMU_NOTIFIER_INVALIDATION: for entry removals (cache invalidates)

When registering the IOMMU notifier, we need to specify one or multiple
capability bit(s) to listen to.

When notifications are triggered, it will be checked against the
notifier's capability bits, and only notifiers with registered bits will
be notified.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 hw/vfio/common.c              |  5 +++--
 include/exec/memory.h         | 37 +++++++++++++++++++++++++++++++------
 include/hw/vfio/vfio-common.h |  2 +-
 memory.c                      | 35 ++++++++++++++++++++++++++++-------
 4 files changed, 63 insertions(+), 16 deletions(-)

On 06/09/2016 15:24, Peter Xu wrote:
> IOMMU Notifier list is used for notifying IO address mapping changes.
> Currently VFIO is the only user.
> 
> However it is possible that future consumer like vhost would like to
> only listen to part of its notifications (e.g., cache invalidations).
> 
> This patch introduced IOMMUNotifier and IOMMUNotfierCap bits for a finer
> grained control of it.
> 
> IOMMUNotifier contains a bitfield for the notify consumer describing
> what kind of notification it is interested in. Currently two kinds of
> notifications are defined:
> 
> - IOMMU_NOTIFIER_CHANGE:       for entry changes (additions)
> - IOMMU_NOTIFIER_INVALIDATION: for entry removals (cache invalidates)
> 
> When registering the IOMMU notifier, we need to specify one or multiple
> capability bit(s) to listen to.
> 
> When notifications are triggered, it will be checked against the
> notifier's capability bits, and only notifiers with registered bits will
> be notified.

Since you're walking the notifier list manually anyway, I think it's
simpler to get rid of Notifier completely.  Otherwise, this looks pretty
good!

Paolo

> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  hw/vfio/common.c              |  5 +++--
>  include/exec/memory.h         | 37 +++++++++++++++++++++++++++++++------
>  include/hw/vfio/vfio-common.h |  2 +-
>  memory.c                      | 35 ++++++++++++++++++++++++++++-------
>  4 files changed, 63 insertions(+), 16 deletions(-)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index b313e7c..04e1cb4 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -295,7 +295,7 @@ static bool vfio_listener_skipped_section(MemoryRegionSection *section)
>  
>  static void vfio_iommu_map_notify(Notifier *n, void *data)
>  {
> -    VFIOGuestIOMMU *giommu = container_of(n, VFIOGuestIOMMU, n);
> +    VFIOGuestIOMMU *giommu = container_of(n, VFIOGuestIOMMU, n.notifier);
>      VFIOContainer *container = giommu->container;
>      IOMMUTLBEntry *iotlb = data;
>      hwaddr iova = iotlb->iova + giommu->iommu_offset;
> @@ -453,7 +453,8 @@ static void vfio_listener_region_add(MemoryListener *listener,
>          giommu->iommu_offset = section->offset_within_address_space -
>                                 section->offset_within_region;
>          giommu->container = container;
> -        giommu->n.notify = vfio_iommu_map_notify;
> +        giommu->n.notifier.notify = vfio_iommu_map_notify;
> +        giommu->n.notifier_caps = IOMMU_NOTIFIER_ALL;
>          QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next);
>  
>          memory_region_register_iommu_notifier(giommu->iommu, &giommu->n);
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 3e4d416..52914c1 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -67,6 +67,27 @@ struct IOMMUTLBEntry {
>      IOMMUAccessFlags perm;
>  };
>  
> +/*
> + * Bitmap for differnet IOMMUNotifier capabilities. Each notifier can
> + * register with one or multiple IOMMU Notifier capability bit(s).
> + */
> +typedef enum {
> +    IOMMU_NOTIFIER_NONE = 0,
> +    /* Notify cache invalidations */
> +    IOMMU_NOTIFIER_INVALIDATION = 0x1,
> +    /* Notify entry changes (newly created entries) */
> +    IOMMU_NOTIFIER_CHANGE = 0x2,
> +} IOMMUNotifierCap;
> +
> +#define IOMMU_NOTIFIER_ALL (IOMMU_NOTIFIER_INVALIDATION | \
> +                            IOMMU_NOTIFIER_CHANGE)
> +
> +struct IOMMUNotifier {
> +    Notifier notifier;
> +    IOMMUNotifierCap notifier_caps;
> +};
> +typedef struct IOMMUNotifier IOMMUNotifier;
> +
>  /* New-style MMIO accessors can indicate that the transaction failed.
>   * A zero (MEMTX_OK) response means success; anything else is a failure
>   * of some kind. The memory subsystem will bitwise-OR together results
> @@ -620,11 +641,13 @@ void memory_region_notify_iommu(MemoryRegion *mr,
>   * IOMMU translation entries.
>   *
>   * @mr: the memory region to observe
> - * @n: the notifier to be added; the notifier receives a pointer to an
> - *     #IOMMUTLBEntry as the opaque value; the pointer ceases to be
> - *     valid on exit from the notifier.
> + * @n: the IOMMUNotifier to be added; the Notifier within the
> + *     IOMMUNotifier receives a pointer to an #IOMMUTLBEntry as the
> + *     opaque value; the pointer ceases to be valid on exit from the
> + *     notifier.
>   */
> -void memory_region_register_iommu_notifier(MemoryRegion *mr, Notifier *n);
> +void memory_region_register_iommu_notifier(MemoryRegion *mr,
> +                                           IOMMUNotifier *n);
>  
>  /**
>   * memory_region_iommu_replay: replay existing IOMMU translations to
> @@ -636,7 +659,8 @@ void memory_region_register_iommu_notifier(MemoryRegion *mr, Notifier *n);
>   * @is_write: Whether to treat the replay as a translate "write"
>   *     through the iommu
>   */
> -void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n, bool is_write);
> +void memory_region_iommu_replay(MemoryRegion *mr, IOMMUNotifier *n,
> +                                bool is_write);
>  
>  /**
>   * memory_region_unregister_iommu_notifier: unregister a notifier for
> @@ -646,7 +670,8 @@ void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n, bool is_write);
>   *      needs to be called
>   * @n: the notifier to be removed.
>   */
> -void memory_region_unregister_iommu_notifier(MemoryRegion *mr, Notifier *n);
> +void memory_region_unregister_iommu_notifier(MemoryRegion *mr,
> +                                             IOMMUNotifier *n);
>  
>  /**
>   * memory_region_name: get a memory region's name
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index 94dfae3..c17602e 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -93,7 +93,7 @@ typedef struct VFIOGuestIOMMU {
>      VFIOContainer *container;
>      MemoryRegion *iommu;
>      hwaddr iommu_offset;
> -    Notifier n;
> +    IOMMUNotifier n;
>      QLIST_ENTRY(VFIOGuestIOMMU) giommu_next;
>  } VFIOGuestIOMMU;
>  
> diff --git a/memory.c b/memory.c
> index 0eb6895..f513c5a 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1513,13 +1513,16 @@ bool memory_region_is_logging(MemoryRegion *mr, uint8_t client)
>      return memory_region_get_dirty_log_mask(mr) & (1 << client);
>  }
>  
> -void memory_region_register_iommu_notifier(MemoryRegion *mr, Notifier *n)
> +void memory_region_register_iommu_notifier(MemoryRegion *mr,
> +                                           IOMMUNotifier *n)
>  {
> +    /* We need to register for at least one bitfield */
> +    assert(n->notifier_caps != IOMMU_NOTIFIER_NONE);
>      if (mr->iommu_ops->notify_started &&
>          QLIST_EMPTY(&mr->iommu_notify.notifiers)) {
>          mr->iommu_ops->notify_started(mr);
>      }
> -    notifier_list_add(&mr->iommu_notify, n);
> +    notifier_list_add(&mr->iommu_notify, &n->notifier);
>  }
>  
>  uint64_t memory_region_iommu_get_min_page_size(MemoryRegion *mr)
> @@ -1531,7 +1534,8 @@ uint64_t memory_region_iommu_get_min_page_size(MemoryRegion *mr)
>      return TARGET_PAGE_SIZE;
>  }
>  
> -void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n, bool is_write)
> +void memory_region_iommu_replay(MemoryRegion *mr, IOMMUNotifier *n,
> +                                bool is_write)
>  {
>      hwaddr addr, granularity;
>      IOMMUTLBEntry iotlb;
> @@ -1541,7 +1545,7 @@ void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n, bool is_write)
>      for (addr = 0; addr < memory_region_size(mr); addr += granularity) {
>          iotlb = mr->iommu_ops->translate(mr, addr, is_write);
>          if (iotlb.perm != IOMMU_NONE) {
> -            n->notify(n, &iotlb);
> +            n->notifier.notify(&n->notifier, &iotlb);
>          }
>  
>          /* if (2^64 - MR size) < granularity, it's possible to get an
> @@ -1552,9 +1556,10 @@ void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n, bool is_write)
>      }
>  }
>  
> -void memory_region_unregister_iommu_notifier(MemoryRegion *mr, Notifier *n)
> +void memory_region_unregister_iommu_notifier(MemoryRegion *mr,
> +                                             IOMMUNotifier *n)
>  {
> -    notifier_remove(n);
> +    notifier_remove(&n->notifier);
>      if (mr->iommu_ops->notify_stopped &&
>          QLIST_EMPTY(&mr->iommu_notify.notifiers)) {
>          mr->iommu_ops->notify_stopped(mr);
> @@ -1564,8 +1569,24 @@ void memory_region_unregister_iommu_notifier(MemoryRegion *mr, Notifier *n)
>  void memory_region_notify_iommu(MemoryRegion *mr,
>                                  IOMMUTLBEntry entry)
>  {
> +    IOMMUNotifier *iommu_notify;
> +    IOMMUNotifierCap request_cap;
> +    Notifier *notifier, *next;
> +
>      assert(memory_region_is_iommu(mr));
> -    notifier_list_notify(&mr->iommu_notify, &entry);
> +
> +    if (entry.perm & IOMMU_RW) {
> +        request_cap = IOMMU_NOTIFIER_CHANGE;
> +    } else {
> +        request_cap = IOMMU_NOTIFIER_INVALIDATION;
> +    }
> +
> +    QLIST_FOREACH_SAFE(notifier, &mr->iommu_notify.notifiers, node, next) {
> +        iommu_notify = container_of(notifier, IOMMUNotifier, notifier);
> +        if (iommu_notify->notifier_caps & request_cap) {
> +            notifier->notify(notifier, &entry);
> +        }
> +    }
>  }
>  
>  void memory_region_set_log(MemoryRegion *mr, bool log, unsigned client)
>

On Tue, Sep 06, 2016 at 04:29:52PM +0200, Paolo Bonzini wrote:
> Since you're walking the notifier list manually anyway, I think it's
> simpler to get rid of Notifier completely.  Otherwise, this looks pretty
> good!

Yes that should be cleaner. Will fix. Thanks!

-- peterx