hw/i386/pc: Allow instantiating a virtio-iommu device

Allow instantiating a virtio-iommu device by adding an ACPI Virtual I/O
Translation table (VIOT), which describes the relation between the
virtio-iommu and the endpoints it manages.

Add a hotplug handler for virtio-iommu on x86 and set the necessary
reserved region property. On x86, the [0xfee00000, 0xfeefffff] DMA
region is reserved for MSIs. DMA transactions to this range either
trigger IRQ remapping in the IOMMU or bypasses IOMMU translation.

Although virtio-iommu does not support IRQ remapping it must be informed
of the reserved region so that it can forward DMA transactions targeting
this region.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Message-Id: <20211026182024.2642038-5-jean-philippe@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/i386/Kconfig

@@ -59,6 +59,7 @@ config PC_ACPI
     select ACPI_X86
     select ACPI_CPU_HOTPLUG
     select ACPI_MEMORY_HOTPLUG
+    select ACPI_VIOT
     select SMBUS_EEPROM
     select PFLASH_CFI01
     depends on ACPI_SMBUS

hw/i386/acpi-build.c

@@ -68,9 +68,11 @@
 #include "qom/qom-qobject.h"
 #include "hw/i386/amd_iommu.h"
 #include "hw/i386/intel_iommu.h"
+#include "hw/virtio/virtio-iommu.h"
 
 #include "hw/acpi/ipmi.h"
 #include "hw/acpi/hmat.h"
+#include "hw/acpi/viot.h"
 
 /* These are used to size the ACPI tables for -M pc-i440fx-1.7 and
  * -M pc-i440fx-2.0.  Even if the actual amount of AML generated grows
@@ -2488,7 +2490,7 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
     PCMachineState *pcms = PC_MACHINE(machine);
     PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
     X86MachineState *x86ms = X86_MACHINE(machine);
-    X86IOMMUState *iommu = x86_iommu_get_default();
+    DeviceState *iommu = pcms->iommu;
     GArray *table_offsets;
     unsigned facs, dsdt, rsdt, fadt;
     AcpiPmInfo pm;
@@ -2613,6 +2615,12 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
         acpi_add_table(table_offsets, tables_blob);
         build_dmar_q35(tables_blob, tables->linker, x86ms->oem_id,
                        x86ms->oem_table_id);
+    } else if (object_dynamic_cast(OBJECT(iommu), TYPE_VIRTIO_IOMMU_PCI)) {
+        PCIDevice *pdev = PCI_DEVICE(iommu);
+
+        acpi_add_table(table_offsets, tables_blob);
+        build_viot(machine, tables_blob, tables->linker, pci_get_bdf(pdev),
+                   x86ms->oem_id, x86ms->oem_table_id);
     }
     if (machine->nvdimms_state->is_enabled) {
         nvdimm_build_acpi(table_offsets, tables_blob, tables->linker,

hw/i386/pc.c

@@ -83,6 +83,7 @@
 #include "hw/i386/intel_iommu.h"
 #include "hw/net/ne2000-isa.h"
 #include "standard-headers/asm-x86/bootparam.h"
+#include "hw/virtio/virtio-iommu.h"
 #include "hw/virtio/virtio-pmem-pci.h"
 #include "hw/virtio/virtio-mem-pci.h"
 #include "hw/mem/memory-device.h"
@@ -1330,7 +1331,19 @@ static void pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_PMEM_PCI) ||
                object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
         pc_virtio_md_pci_pre_plug(hotplug_dev, dev, errp);
-    } else if (object_dynamic_cast(OBJECT(dev), TYPE_X86_IOMMU_DEVICE)) {
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
+        /* Declare the APIC range as the reserved MSI region */
+        char *resv_prop_str = g_strdup_printf("0xfee00000:0xfeefffff:%d",
+                                              VIRTIO_IOMMU_RESV_MEM_T_MSI);
+
+        object_property_set_uint(OBJECT(dev), "len-reserved-regions", 1, errp);
+        object_property_set_str(OBJECT(dev), "reserved-regions[0]",
+                                resv_prop_str, errp);
+        g_free(resv_prop_str);
+    }
+
+    if (object_dynamic_cast(OBJECT(dev), TYPE_X86_IOMMU_DEVICE) ||
+        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
         PCMachineState *pcms = PC_MACHINE(hotplug_dev);
 
         if (pcms->iommu) {
@@ -1394,6 +1407,7 @@ static HotplugHandler *pc_get_hotplug_handler(MachineState *machine,
         object_dynamic_cast(OBJECT(dev), TYPE_CPU) ||
         object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_PMEM_PCI) ||
         object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI) ||
+        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI) ||
         object_dynamic_cast(OBJECT(dev), TYPE_X86_IOMMU_DEVICE)) {
         return HOTPLUG_HANDLER(machine);
     }