Re: [PATCH for-5.0 v11 08/20] virtio-iommu: Implement translate

[Peter Xu]

On Fri, Nov 22, 2019 at 07:29:31PM +0100, Eric Auger wrote:
> This patch implements the translate callback
> 
> Signed-off-by: Eric Auger <address@hidden>
> 
> ---
> 
> v10 -> v11:
> - take into account the new value struct and use
>   g_tree_lookup_extended
> - switched to error_report_once
> 
> v6 -> v7:
> - implemented bypass-mode
> 
> v5 -> v6:
> - replace error_report by qemu_log_mask
> 
> v4 -> v5:
> - check the device domain is not NULL
> - s/printf/error_report
> - set flags to IOMMU_NONE in case of all translation faults
> ---
>  hw/virtio/trace-events   |  1 +
>  hw/virtio/virtio-iommu.c | 63 +++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 63 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> index f25359cee2..de7cbb3c8f 100644
> --- a/hw/virtio/trace-events
> +++ b/hw/virtio/trace-events
> @@ -72,3 +72,4 @@ virtio_iommu_get_endpoint(uint32_t ep_id) "Alloc 
> endpoint=%d"
>  virtio_iommu_put_endpoint(uint32_t ep_id) "Free endpoint=%d"
>  virtio_iommu_get_domain(uint32_t domain_id) "Alloc domain=%d"
>  virtio_iommu_put_domain(uint32_t domain_id) "Free domain=%d"
> +virtio_iommu_translate_out(uint64_t virt_addr, uint64_t phys_addr, uint32_t 
> sid) "0x%"PRIx64" -> 0x%"PRIx64 " for sid=%d"
> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
> index f0a56833a2..a83666557b 100644
> --- a/hw/virtio/virtio-iommu.c
> +++ b/hw/virtio/virtio-iommu.c
> @@ -412,19 +412,80 @@ static IOMMUTLBEntry 
> virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
>                                              int iommu_idx)
>  {
>      IOMMUDevice *sdev = container_of(mr, IOMMUDevice, iommu_mr);
> +    viommu_interval interval, *mapping_key;
> +    viommu_mapping *mapping_value;
> +    VirtIOIOMMU *s = sdev->viommu;
> +    viommu_endpoint *ep;
> +    bool bypass_allowed;
>      uint32_t sid;
> +    bool found;
> +
> +    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);
> +

Would it be easier to check bypass_allowed here once and then drop the
latter [1] and [2] check?

>      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) {

[1]

> +            error_report_once("%s sid=%d is not known!!", __func__, sid);
> +        } else {
> +            entry.perm = flag;
> +        }
> +        goto unlock;
> +    }
> +
> +    if (!ep->domain) {
> +        if (!bypass_allowed) {

[2]

> +            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;
> +    }
> +
> +    found = g_tree_lookup_extended(ep->domain->mappings, 
> (gpointer)(&interval),
> +                                   (void **)&mapping_key,
> +                                   (void **)&mapping_value);
> +    if (!found) {
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "%s no mapping for 0x%"PRIx64" for sid=%d\n",
> +                      __func__, addr, sid);

I would still suggest that we use the same logging interface (either
error_report_once() or qemu_log_mask(), not use them randomly).

> +        goto unlock;
> +    }
> +
> +    if (((flag & IOMMU_RO) &&
> +            !(mapping_value->flags & VIRTIO_IOMMU_MAP_F_READ)) ||
> +        ((flag & IOMMU_WO) &&
> +            !(mapping_value->flags & VIRTIO_IOMMU_MAP_F_WRITE))) {
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "Permission error on 0x%"PRIx64"(%d): allowed=%d\n",
> +                      addr, flag, mapping_value->flags);

(Btw, IIUC this may not be a guest error. Say, what if the device is
 simply broken?)

> +        goto unlock;
> +    }
> +    entry.translated_addr = addr - mapping_key->low + 
> mapping_value->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
> 

-- 
Peter Xu