[PATCH v4 07/11] pc: Allow instantiating a virtio-iommu device

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

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.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 include/hw/i386/pc.h |  2 ++
 hw/i386/acpi-build.c |  5 +++++
 hw/i386/pc.c         | 24 ++++++++++++++++++++++--
 hw/i386/Kconfig      |  1 +
 4 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 82cf7b7e30..f3ba1ee4c0 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -45,6 +45,8 @@ typedef struct PCMachineState {
     bool pit_enabled;
     bool hpet_enabled;
     bool default_bus_bypass_iommu;
+    bool virtio_iommu;
+    uint16_t virtio_iommu_bdf;
     uint64_t max_fw_size;
 
     /* ACPI Memory hotplug IO base address */
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index d1c28440f4..4e46585709 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -71,6 +71,7 @@
 
 #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
@@ -2593,6 +2594,10 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
             build_dmar_q35(tables_blob, tables->linker, x86ms->oem_id,
                            x86ms->oem_table_id);
         }
+    } else if (pcms->virtio_iommu) {
+        acpi_add_table(table_offsets, tables_blob);
+        build_viot(machine, tables_blob, tables->linker, pcms->virtio_iommu_bdf,
+                   x86ms->oem_id, x86ms->oem_table_id);
     }
     if (machine->nvdimms_state->is_enabled) {
         nvdimm_build_acpi(table_offsets, tables_blob, tables->linker,
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 789ccb6ef4..31710bc4fb 100644
--- a/hw/i386/pc.c
+++ b/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"
@@ -1367,8 +1368,11 @@ static void pc_virtio_md_pci_unplug(HotplugHandler *hotplug_dev,
 static void pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
                                           DeviceState *dev, Error **errp)
 {
-    if (object_dynamic_cast(OBJECT(dev), TYPE_X86_IOMMU_DEVICE) &&
-        x86_iommu_get_default()) {
+    PCMachineState *pcms = PC_MACHINE(hotplug_dev);
+
+    if ((object_dynamic_cast(OBJECT(dev), TYPE_X86_IOMMU_DEVICE) ||
+         object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) &&
+        (x86_iommu_get_default() || pcms->virtio_iommu)) {
         error_setg(errp, "QEMU does not support multiple vIOMMUs "
                    "for x86 yet.");
         return;
@@ -1381,6 +1385,15 @@ 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_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);
     }
 }
 
@@ -1394,6 +1407,12 @@ static void pc_machine_device_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_plug(hotplug_dev, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
+        PCMachineState *pcms = PC_MACHINE(hotplug_dev);
+        PCIDevice *pdev = PCI_DEVICE(dev);
+
+        pcms->virtio_iommu = true;
+        pcms->virtio_iommu_bdf = pci_get_bdf(pdev);
     }
 }
 
@@ -1436,6 +1455,7 @@ 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);
     }
diff --git a/hw/i386/Kconfig b/hw/i386/Kconfig
index ddedcef0b2..13db05d557 100644
--- a/hw/i386/Kconfig
+++ b/hw/i386/Kconfig
@@ -54,6 +54,7 @@ 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
-- 
2.33.0