[PATCH v7 3/5] virtio-iommu: Handle reserved regions in the translation process

[Eric Auger <eric.auger@redhat.com>]

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

---

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 2cdaa1969b..b39e836181 100644
--- a/hw/virtio/virtio-iommu.c
+++ b/hw/virtio/virtio-iommu.c
@@ -607,6 +607,7 @@ 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;
@@ -640,6 +641,25 @@ 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