From: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>

Enable the appropriate memory region for an address space depending on the
address translation mode selected for it. This is currently based on a
generic x86 IOMMU property, and only done during the address space
initialization. Extract the code into a helper and toggle the regions based
on whether the specific address space is using address translation (via the
newly introduced addr_translation field). Later, region activation will also
be controlled by availability of DMA remapping capability (via dma-remap
property to be introduced in follow up changes).

Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20250919213515.917111-16-alejandro.j.jimenez@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/i386/amd_iommu.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
index d74d42b3dd..67a26f5247 100644
--- a/hw/i386/amd_iommu.c
+++ b/hw/i386/amd_iommu.c
@@ -74,6 +74,8 @@ struct AMDVIAddressSpace {
     QLIST_ENTRY(AMDVIAddressSpace) next;
     /* Record DMA translation ranges */
     IOVATree *iova_tree;
+    /* DMA address translation active */
+    bool addr_translation;
 };
 
 /* AMDVI cache entry */
@@ -982,6 +984,23 @@ static void amdvi_iommu_address_space_sync_all(AMDVIState *s)
     }
 }
 
+/*
+ * Toggle between address translation and passthrough modes by enabling the
+ * corresponding memory regions.
+ */
+static void amdvi_switch_address_space(AMDVIAddressSpace *amdvi_as)
+{
+    if (amdvi_as->addr_translation) {
+        /* Enabling DMA region */
+        memory_region_set_enabled(&amdvi_as->iommu_nodma, false);
+        memory_region_set_enabled(MEMORY_REGION(&amdvi_as->iommu), true);
+    } else {
+        /* Disabling DMA region, using passthrough */
+        memory_region_set_enabled(MEMORY_REGION(&amdvi_as->iommu), false);
+        memory_region_set_enabled(&amdvi_as->iommu_nodma, true);
+    }
+}
+
 /* log error without aborting since linux seems to be using reserved bits */
 static void amdvi_inval_devtab_entry(AMDVIState *s, uint64_t *cmd)
 {
@@ -2070,6 +2089,7 @@ static AddressSpace *amdvi_host_dma_iommu(PCIBus *bus, void *opaque, int devfn)
         iommu_as[devfn]->iommu_state = s;
         iommu_as[devfn]->notifier_flags = IOMMU_NOTIFIER_NONE;
         iommu_as[devfn]->iova_tree = iova_tree_new();
+        iommu_as[devfn]->addr_translation = false;
 
         amdvi_dev_as = iommu_as[devfn];
 
@@ -2112,8 +2132,7 @@ static AddressSpace *amdvi_host_dma_iommu(PCIBus *bus, void *opaque, int devfn)
                                             AMDVI_INT_ADDR_FIRST,
                                             &amdvi_dev_as->iommu_ir, 1);
 
-        memory_region_set_enabled(&amdvi_dev_as->iommu_nodma, false);
-        memory_region_set_enabled(MEMORY_REGION(&amdvi_dev_as->iommu), true);
+        amdvi_switch_address_space(amdvi_dev_as);
     }
     return &iommu_as[devfn]->as;
 }
-- 
MST