Re: [Qemu-devel] [PATCH for-4.2 v10 09/15] virtio-iommu: Implement translate

[Peter Xu]

On Tue, Jul 30, 2019 at 07:21:31PM +0200, Eric Auger wrote:
> @@ -464,19 +464,75 @@ static IOMMUTLBEntry 
> virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
>                                              int iommu_idx)
>  {
>      IOMMUDevice *sdev = container_of(mr, IOMMUDevice, iommu_mr);
> +    VirtIOIOMMU *s = sdev->viommu;
>      uint32_t sid;
> +    viommu_endpoint *ep;
> +    viommu_mapping *mapping;
> +    viommu_interval interval;
> +    bool bypass_allowed;
> +
> +    interval.low = addr;
> +    interval.high = addr + 1;
>  
>      IOMMUTLBEntry entry = {
>          .target_as = &address_space_memory,
>          .iova = addr,
>          .translated_addr = addr,
> -        .addr_mask = ~(hwaddr)0,
> +        .addr_mask = (1 << ctz32(s->config.page_size_mask)) - 1,
>          .perm = IOMMU_NONE,
>      };
>  
> +    bypass_allowed = virtio_has_feature(s->acked_features,
> +                                        VIRTIO_IOMMU_F_BYPASS);
> +
>      sid = virtio_iommu_get_sid(sdev);
>  
>      trace_virtio_iommu_translate(mr->parent_obj.name, sid, addr, flag);
> +    qemu_mutex_lock(&s->mutex);
> +
> +    ep = g_tree_lookup(s->endpoints, GUINT_TO_POINTER(sid));
> +    if (!ep) {
> +        if (!bypass_allowed) {
> +            error_report("%s sid=%d is not known!!", __func__, sid);

Maybe use error_report_once() to avoid DOS attack?  Also would it be
good to unify the debug prints?  I see both error_report() and
qemu_log_mask() are used in the whole patchset.  Or is that attempted?

> +        } else {
> +            entry.perm = flag;
> +        }
> +        goto unlock;
> +    }
> +
> +    if (!ep->domain) {
> +        if (!bypass_allowed) {
> +            qemu_log_mask(LOG_GUEST_ERROR,
> +                          "%s %02x:%02x.%01x not attached to any domain\n",
> +                          __func__, PCI_BUS_NUM(sid),
> +                          PCI_SLOT(sid), PCI_FUNC(sid));
> +        } else {
> +            entry.perm = flag;
> +        }
> +        goto unlock;
> +    }
> +
> +    mapping = g_tree_lookup(ep->domain->mappings, (gpointer)(&interval));
> +    if (!mapping) {
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "%s no mapping for 0x%"PRIx64" for sid=%d\n",
> +                      __func__, addr, sid);
> +        goto unlock;
> +    }
> +
> +    if (((flag & IOMMU_RO) && !(mapping->flags & VIRTIO_IOMMU_MAP_F_READ)) ||
> +        ((flag & IOMMU_WO) && !(mapping->flags & VIRTIO_IOMMU_MAP_F_WRITE))) 
> {
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "Permission error on 0x%"PRIx64"(%d): allowed=%d\n",
> +                      addr, flag, mapping->flags);
> +        goto unlock;
> +    }
> +    entry.translated_addr = addr - mapping->virt_addr + mapping->phys_addr;
> +    entry.perm = flag;
> +    trace_virtio_iommu_translate_out(addr, entry.translated_addr, sid);
> +
> +unlock:
> +    qemu_mutex_unlock(&s->mutex);
>      return entry;
>  }
>  
> -- 
> 2.20.1
> 

Regards,

-- 
Peter Xu