Re: [PATCH v3 3/5] virtio-iommu: Handle reserved regions in the translation process

[Jean-Philippe Brucker]

On Thu, Jun 11, 2020 at 05:12:07PM +0200, Eric Auger wrote:
> When translating an address we need to check if it belongs to
> a reserved virtual address range. If it does, there are 2 cases:
> 
> - it belongs to a RESERVED region: the guest should neither use
>   this address in a MAP not instruct the end-point to DMA on
>   them. We report an error
> 
> - It belongs to an MSI region: we bypass the translation.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> Reviewed-by: Peter Xu <peterx@redhat.com>
> 

Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

> ---
> 
> v1 -> v2:
> - use addr when testing addr belongs to the reserved region
>   and use a block local variable
> ---
>  hw/virtio/virtio-iommu.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
> index be1527c1d6..03535a6a14 100644
> --- a/hw/virtio/virtio-iommu.c
> +++ b/hw/virtio/virtio-iommu.c
> @@ -604,6 +604,7 @@ static IOMMUTLBEntry 
> virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
>      uint32_t sid, flags;
>      bool bypass_allowed;
>      bool found;
> +    int i;
>  
>      interval.low = addr;
>      interval.high = addr + 1;
> @@ -637,6 +638,25 @@ static IOMMUTLBEntry 
> virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr,
>          goto unlock;
>      }
>  
> +    for (i = 0; i < s->nb_reserved_regions; i++) {
> +        ReservedRegion *reg = &s->reserved_regions[i];
> +
> +        if (addr >= reg->low && addr <= reg->high) {
> +            switch (reg->type) {
> +            case VIRTIO_IOMMU_RESV_MEM_T_MSI:
> +                entry.perm = flag;
> +                break;
> +            case VIRTIO_IOMMU_RESV_MEM_T_RESERVED:
> +            default:
> +                virtio_iommu_report_fault(s, VIRTIO_IOMMU_FAULT_R_MAPPING,
> +                                          VIRTIO_IOMMU_FAULT_F_ADDRESS,
> +                                          sid, addr);
> +                break;
> +            }
> +            goto unlock;
> +        }
> +    }
> +
>      if (!ep->domain) {
>          if (!bypass_allowed) {
>              error_report_once("%s %02x:%02x.%01x not attached to any domain",
> -- 
> 2.20.1
>