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On 24/09/2015 01:50, David Gibson wrote: > On Wed, Sep 23, 2015 at 07:04:55PM +0200, Laurent Vivier wrote: >> >> >> On 17/09/2015 15:09, David Gibson wrote: >>> When we have guest visible IOMMUs, we allow notifiers to be >>> registered which will be informed of all changes to IOMMU >>> mappings. This is used by vfio to keep the host IOMMU mappings >>> in sync with guest IOMMU mappings. >>> >>> However, unlike with a memory region listener, an iommu >>> notifier won't be told about any mappings which already exist >>> in the (guest) IOMMU at the time it is registered. This can >>> cause problems if hotplugging a VFIO device onto a guest bus >>> which had existing guest IOMMU mappings, but didn't previously >>> have an VFIO devices (and hence no host IOMMU mappings). >>> >>> This adds a memory_region_register_iommu_notifier_replay() >>> function to handle this case. As well as registering the new >>> notifier it replays existing mappings. Because the IOMMU >>> memory region doesn't internally remember the granularity of >>> the guest IOMMU it has a small hack where the caller must >>> specify a granularity at which to replay mappings. >>> >>> If there are finer mappings in the guest IOMMU these will be >>> reported in the iotlb structures passed to the notifier which >>> it must handle (probably causing it to flag an error). This >>> isn't new - the VFIO iommu notifier must already handle >>> notifications about guest IOMMU mappings too short for it to >>> represent in the host IOMMU. >>> >>> Signed-off-by: David Gibson <da...@gibson.dropbear.id.au> --- >>> include/exec/memory.h | 16 ++++++++++++++++ memory.c >>> | 18 ++++++++++++++++++ 2 files changed, 34 insertions(+) >>> >>> diff --git a/include/exec/memory.h b/include/exec/memory.h >>> index 5baaf48..3cf145b 100644 --- a/include/exec/memory.h +++ >>> b/include/exec/memory.h @@ -583,6 +583,22 @@ void >>> memory_region_notify_iommu(MemoryRegion *mr, void >>> memory_region_register_iommu_notifier(MemoryRegion *mr, >>> Notifier *n); >>> >>> /** + * memory_region_register_iommu_notifier_replay: register >>> a notifier + * for changes to IOMMU translation entries, and >>> replay existing IOMMU + * translations to the new notifier. + >>> * + * @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. + * @granularity: >>> Minimum page granularity to replay notifications for + * >>> @is_write: Whether to treat the replay as a translate "write" + >>> * through the iommu + */ +void >>> memory_region_register_iommu_notifier_replay(MemoryRegion *mr, >>> Notifier *n, + >>> hwaddr granularity, bool is_write); + +/** * >>> memory_region_unregister_iommu_notifier: unregister a notifier >>> for * changes to IOMMU translation entries. * diff --git >>> a/memory.c b/memory.c index 0d8b2d9..6b5a2f1 100644 --- >>> a/memory.c +++ b/memory.c @@ -1403,6 +1403,24 @@ void >>> memory_region_register_iommu_notifier(MemoryRegion *mr, >>> Notifier *n) notifier_list_add(&mr->iommu_notify, n); } >>> >>> +void memory_region_register_iommu_notifier_replay(MemoryRegion >>> *mr, Notifier *n, + >>> hwaddr granularity, bool is_write) +{ + hwaddr addr; + >>> IOMMUTLBEntry iotlb; + + >>> memory_region_register_iommu_notifier(mr, n); + + for (addr >>> = 0; + int128_lt(int128_make64(addr), mr->size); >> >> "addr < memory_region_size(mr)" should be enough. > > Ah, yes, much neater, thanks. but rethinking about that, you can have an infinite loop (with int128 or with memory_region_size()) if mr->size >= UINT64_MAX: as hwaddr is a 64bit and a multiple of granularity which is a power of two. the last value of addr is UINT64 + 1 - granularity, so the next is (uint64_t)(UINT64 + 1), which is 0, so addr is never >= mr->size. > >>> + addr += granularity) { + + iotlb = >>> mr->iommu_ops->translate(mr, addr, is_write); + if >>> (iotlb.perm != IOMMU_NONE) + n->notify(n, &iotlb); + >>> } +} + void memory_region_unregister_iommu_notifier(Notifier >>> *n) { notifier_remove(n); >>> >> > -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEARECAAYFAlYDob0ACgkQNKT2yavzbFOnFACcDk+2PHhX/WfCCkTdXKH4XhWi UYcAoOpe+C+8tzX02VlGTsCAV9ZxiEwQ =Cnfl -----END PGP SIGNATURE-----