Re: [PATCH v2 01/20] memory: Adjust event ranges to fit within notifier boundaries

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, May 02, 2025 at 02:15:46AM +0000, Alejandro Jimenez wrote:
> Invalidating the entire address space (i.e. range of [0, ~0ULL]) is a
> valid and required operation by vIOMMU implementations. However, such
> invalidations currently trigger an assertion unless they originate from
> device IOTLB invalidations.
> 
> Although in recent Linux guests this case is not exercised by the VTD
> implementation due to various optimizations, the assertion will be hit
> by upcoming AMD vIOMMU changes to support DMA address translation. More
> specifically, when running a Linux guest with VFIO passthrough device,
> and a kernel that does not contain commmit 3f2571fed2fa ("iommu/amd:
> Remove redundant domain flush from attach_device()").
> 
> Remove the assertion altogether and adjust the range to ensure it does
> not cross notifier boundaries.
> 
> Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>

Looks legit:

Acked-by: Michael S. Tsirkin <mst@redhat.com>

can we get an ack from memory API supporters?

> ---
>  system/memory.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/system/memory.c b/system/memory.c
> index 71434e7ad02c..7ad2fc098341 100644
> --- a/system/memory.c
> +++ b/system/memory.c
> @@ -2021,13 +2021,9 @@ void memory_region_notify_iommu_one(IOMMUNotifier *notifier,
>          return;
>      }
>  
> -    if (notifier->notifier_flags & IOMMU_NOTIFIER_DEVIOTLB_UNMAP) {
> -        /* Crop (iova, addr_mask) to range */
> -        tmp.iova = MAX(tmp.iova, notifier->start);
> -        tmp.addr_mask = MIN(entry_end, notifier->end) - tmp.iova;
> -    } else {
> -        assert(entry->iova >= notifier->start && entry_end <= notifier->end);
> -    }
> +    /* Crop (iova, addr_mask) to range */
> +    tmp.iova = MAX(tmp.iova, notifier->start);
> +    tmp.addr_mask = MIN(entry_end, notifier->end) - tmp.iova;
>  
>      if (event->type & notifier->notifier_flags) {
>          notifier->notify(notifier, &tmp);
> -- 
> 2.43.5