Re: [Qemu-devel] [PATCH RFC v3 09/14] memory: introduce memory_region_notify_one()

[Peter Xu <peterx@redhat.com>]

On Fri, Jan 13, 2017 at 03:58:59PM +0800, Jason Wang wrote:
> 
> 
> On 2017年01月13日 11:06, Peter Xu wrote:
> >Generalizing the notify logic in memory_region_notify_iommu() into a
> >single function. This can be further used in customized replay()
> >functions for IOMMUs.
> >
> >Signed-off-by: Peter Xu <peterx@redhat.com>
> >---
> >  include/exec/memory.h | 15 +++++++++++++++
> >  memory.c              | 29 ++++++++++++++++++-----------
> >  2 files changed, 33 insertions(+), 11 deletions(-)
> >
> >diff --git a/include/exec/memory.h b/include/exec/memory.h
> >index 2233f99..f367e54 100644
> >--- a/include/exec/memory.h
> >+++ b/include/exec/memory.h
> >@@ -669,6 +669,21 @@ void memory_region_notify_iommu(MemoryRegion *mr,
> >                                  IOMMUTLBEntry entry);
> >  /**
> >+ * memory_region_notify_one: notify a change in an IOMMU translation
> >+ *                           entry to a single notifier
> >+ *
> >+ * This works just like memory_region_notify_iommu(), but it only
> >+ * notifies a specific notifier, not all of them.
> >+ *
> >+ * @notifier: the notifier to be notified
> >+ * @entry: the new entry in the IOMMU translation table.  The entry
> >+ *         replaces all old entries for the same virtual I/O address range.
> >+ *         Deleted entries have .@perm == 0.
> >+ */
> >+void memory_region_notify_one(IOMMUNotifier *notifier,
> >+                              IOMMUTLBEntry *entry);
> >+
> >+/**
> >   * memory_region_register_iommu_notifier: register a notifier for changes to
> >   * IOMMU translation entries.
> >   *
> >diff --git a/memory.c b/memory.c
> >index df62bd1..6e4c872 100644
> >--- a/memory.c
> >+++ b/memory.c
> >@@ -1665,26 +1665,33 @@ void memory_region_unregister_iommu_notifier(MemoryRegion *mr,
> >      memory_region_update_iommu_notify_flags(mr);
> >  }
> >-void memory_region_notify_iommu(MemoryRegion *mr,
> >-                                IOMMUTLBEntry entry)
> >+void memory_region_notify_one(IOMMUNotifier *notifier,
> >+                              IOMMUTLBEntry *entry)
> >  {
> >-    IOMMUNotifier *iommu_notifier;
> >      IOMMUNotifierFlag request_flags;
> >-    assert(memory_region_is_iommu(mr));
> >-
> >-    if (entry.perm & IOMMU_RW) {
> >+    if (entry->perm & IOMMU_RW) {
> >          request_flags = IOMMU_NOTIFIER_MAP;
> >      } else {
> >          request_flags = IOMMU_NOTIFIER_UNMAP;
> >      }
> 
> Nit: you can keep this outside the loop.

Yes, but this function is used in vtd_replay_hook() as well in latter
patch. If I keep the above outside loop (IIUC you mean the loop in
memory_region_notify_iommu()), I'll need to set it up as well in
future vtd_replay_hook(), then that'll be slightly awkward.
Considering that the notification will only happen at mapping changes,
I'll prefer to keep the interface cleaner like what this patch has
done.

Thanks,

-- peterx