amd_iommu: Add basic structure to support IOMMU notifier updates

Add the minimal data structures required to maintain a list of address
spaces (i.e. devices) with registered notifiers, and to update the type of
events that require notifications.
Note that the ability to register for MAP notifications is not available.
It will be unblocked by following changes that enable the synchronization of
guest I/O page tables with host IOMMU state, at which point an amd-iommu
device property will be introduced to control this capability.

Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20250919213515.917111-10-alejandro.j.jimenez@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

2 files changed, 23 insertions, 0 deletions

diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
index 0e45435c77..d8a451b3a5 100644
--- a/hw/i386/amd_iommu.c
+++ b/hw/i386/amd_iommu.c
@@ -66,6 +66,11 @@ struct AMDVIAddressSpace {
     MemoryRegion iommu_nodma;   /* Alias of shared nodma memory region  */
     MemoryRegion iommu_ir;      /* Device's interrupt remapping region  */
     AddressSpace as;            /* device's corresponding address space */
+
+    /* DMA address translation support */
+    IOMMUNotifierFlag notifier_flags;
+    /* entry in list of Address spaces with registered notifiers */
+    QLIST_ENTRY(AMDVIAddressSpace) next;
 };
 
 /* AMDVI cache entry */
@@ -1773,6 +1778,7 @@ static AddressSpace *amdvi_host_dma_iommu(PCIBus *bus, void *opaque, int devfn)
         iommu_as[devfn]->bus_num = (uint8_t)bus_num;
         iommu_as[devfn]->devfn = (uint8_t)devfn;
         iommu_as[devfn]->iommu_state = s;
+        iommu_as[devfn]->notifier_flags = IOMMU_NOTIFIER_NONE;
 
         amdvi_dev_as = iommu_as[devfn];
 
@@ -1846,6 +1852,7 @@ static int amdvi_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu,
                                            Error **errp)
 {
     AMDVIAddressSpace *as = container_of(iommu, AMDVIAddressSpace, iommu);
+    AMDVIState *s = as->iommu_state;
 
     if (new & IOMMU_NOTIFIER_MAP) {
         error_setg(errp,
@@ -1854,6 +1861,19 @@ static int amdvi_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu,
                    PCI_FUNC(as->devfn));
         return -EINVAL;
     }
+
+    /*
+     * Update notifier flags for address space and the list of address spaces
+     * with registered notifiers.
+     */
+    as->notifier_flags = new;
+
+    if (old == IOMMU_NOTIFIER_NONE) {
+        QLIST_INSERT_HEAD(&s->amdvi_as_with_notifiers, as, next);
+    } else if (new == IOMMU_NOTIFIER_NONE) {
+        QLIST_REMOVE(as, next);
+    }
+
     return 0;
 }
 
diff --git a/hw/i386/amd_iommu.h b/hw/i386/amd_iommu.h
index 9f833b297d..b51aa74368 100644
--- a/hw/i386/amd_iommu.h
+++ b/hw/i386/amd_iommu.h
@@ -409,6 +409,9 @@ struct AMDVIState {
     /* for each served device */
     AMDVIAddressSpace **address_spaces[PCI_BUS_MAX];
 
+    /* list of address spaces with registered notifiers */
+    QLIST_HEAD(, AMDVIAddressSpace) amdvi_as_with_notifiers;
+
     /* IOTLB */
     GHashTable *iotlb;