[PATCH v2 2/8] hw/acpi: Add VIOT table

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

Add a function that generates a Virtual I/O Translation table (VIOT),
describing the topology of paravirtual IOMMUs. The table is created when
instantiating a virtio-iommu device. It contains a virtio-iommu node and
PCI Range nodes for endpoints managed by the IOMMU. By default, a single
node describes all PCI devices. When passing the "default_bus_bypass_iommu"
machine option and "bypass_iommu" PXB option, only buses that do not
bypass the IOMMU are described by PCI Range nodes.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 hw/acpi/Kconfig     |   4 ++
 hw/acpi/viot.h      |  13 +++++
 hw/acpi/viot.c      | 112 ++++++++++++++++++++++++++++++++++++++++++++
 hw/acpi/meson.build |   1 +
 4 files changed, 130 insertions(+)
 create mode 100644 hw/acpi/viot.h
 create mode 100644 hw/acpi/viot.c

diff --git a/hw/acpi/Kconfig b/hw/acpi/Kconfig
index cfc4ede8d9..abad79c103 100644
--- a/hw/acpi/Kconfig
+++ b/hw/acpi/Kconfig
@@ -41,6 +41,10 @@ config ACPI_VMGENID
     default y
     depends on PC
 
+config ACPI_VIOT
+    bool
+    depends on ACPI
+
 config ACPI_HW_REDUCED
     bool
     select ACPI
diff --git a/hw/acpi/viot.h b/hw/acpi/viot.h
new file mode 100644
index 0000000000..4cef29a640
--- /dev/null
+++ b/hw/acpi/viot.h
@@ -0,0 +1,13 @@
+/*
+ * ACPI Virtual I/O Translation Table implementation
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#ifndef VIOT_H
+#define VIOT_H
+
+void build_viot(GArray *table_data, BIOSLinker *linker,
+                uint16_t virtio_iommu_bdf, const char *oem_id,
+                const char *oem_table_id);
+
+#endif /* VIOT_H */
diff --git a/hw/acpi/viot.c b/hw/acpi/viot.c
new file mode 100644
index 0000000000..81bb2e93ff
--- /dev/null
+++ b/hw/acpi/viot.c
@@ -0,0 +1,112 @@
+/*
+ * ACPI Virtual I/O Translation table implementation
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include "qemu/osdep.h"
+#include "hw/acpi/acpi.h"
+#include "hw/acpi/aml-build.h"
+#include "hw/acpi/viot.h"
+#include "hw/pci/pci.h"
+#include "hw/pci/pci_host.h"
+
+struct viot_pci_ranges {
+    GArray *blob;
+    size_t count;
+    uint16_t output_node;
+};
+
+/* Build PCI range for a given PCI host bridge */
+static int viot_host_bridges(Object *obj, void *opaque)
+{
+    struct viot_pci_ranges *pci_ranges = opaque;
+    GArray *blob = pci_ranges->blob;
+
+    if (object_dynamic_cast(obj, TYPE_PCI_HOST_BRIDGE)) {
+        PCIBus *bus = PCI_HOST_BRIDGE(obj)->bus;
+
+        if (bus && !pci_bus_bypass_iommu(bus)) {
+            int min_bus, max_bus;
+
+            pci_bus_range(bus, &min_bus, &max_bus);
+
+            /* Type */
+            build_append_int_noprefix(blob, ACPI_VIOT_NODE_PCI_RANGE, 1);
+            /* Reserved */
+            build_append_int_noprefix(blob, 0, 1);
+            /* Length */
+            build_append_int_noprefix(blob, sizeof(AcpiViotPciRange), 2);
+            /* Endpoint start */
+            build_append_int_noprefix(blob, PCI_BUILD_BDF(min_bus, 0), 4);
+            /* PCI Segment start */
+            build_append_int_noprefix(blob, 0, 2);
+            /* PCI Segment end */
+            build_append_int_noprefix(blob, 0, 2);
+            /* PCI BDF start */
+            build_append_int_noprefix(blob, PCI_BUILD_BDF(min_bus, 0), 2);
+            /* PCI BDF end */
+            build_append_int_noprefix(blob, PCI_BUILD_BDF(max_bus, 0xff), 2);
+            /* Output node */
+            build_append_int_noprefix(blob, pci_ranges->output_node, 2);
+            /* Reserved */
+            build_append_int_noprefix(blob, 0, 6);
+
+            pci_ranges->count++;
+        }
+    }
+
+    return 0;
+}
+
+/*
+ * Generate a VIOT table with one PCI-based virtio-iommu that manages PCI
+ * endpoints.
+ */
+void build_viot(GArray *table_data, BIOSLinker *linker,
+                uint16_t virtio_iommu_bdf, const char *oem_id,
+                const char *oem_table_id)
+{
+    /* virtio-iommu node follows the header */
+    int viommu_off = sizeof(AcpiViot);
+    int viot_start = table_data->len;
+    struct viot_pci_ranges pci_ranges = {
+        .output_node = viommu_off,
+        .blob = g_array_new(false, true, 1),
+    };
+
+    /* Build the list of PCI ranges that this viommu manages */
+    object_child_foreach_recursive(object_get_root(), viot_host_bridges,
+                                   &pci_ranges);
+
+    /* VIOT header */
+    acpi_data_push(table_data, sizeof(AcpiTableHeader));
+    /* Node count */
+    build_append_int_noprefix(table_data, pci_ranges.count + 1, 2);
+    /* Node offset */
+    build_append_int_noprefix(table_data, viommu_off, 2);
+    /* Reserved */
+    build_append_int_noprefix(table_data, 0, 8);
+
+    /* Virtio-iommu based on virtio-pci */
+    /* Type */
+    build_append_int_noprefix(table_data, ACPI_VIOT_NODE_VIRTIO_IOMMU_PCI, 1);
+    /* Reserved */
+    build_append_int_noprefix(table_data, 0, 1);
+    /* Length */
+    build_append_int_noprefix(table_data, sizeof(AcpiViotVirtioIommuPci), 2);
+    /* PCI Segment */
+    build_append_int_noprefix(table_data, 0, 2);
+    /* PCI BDF number */
+    build_append_int_noprefix(table_data, virtio_iommu_bdf, 2);
+    /* Reserved */
+    build_append_int_noprefix(table_data, 0, 8);
+
+    /* PCI ranges found above */
+    g_array_append_vals(table_data, pci_ranges.blob->data,
+                        pci_ranges.blob->len);
+    g_array_free(pci_ranges.blob, true);
+
+    build_header(linker, table_data, (void *)(table_data->data + viot_start),
+                 "VIOT", table_data->len - viot_start, 0, oem_id, oem_table_id);
+}
+
diff --git a/hw/acpi/meson.build b/hw/acpi/meson.build
index 29f804d13e..a510988b27 100644
--- a/hw/acpi/meson.build
+++ b/hw/acpi/meson.build
@@ -16,6 +16,7 @@ acpi_ss.add(when: 'CONFIG_ACPI_HW_REDUCED', if_true: files('generic_event_device
 acpi_ss.add(when: 'CONFIG_ACPI_HMAT', if_true: files('hmat.c'))
 acpi_ss.add(when: 'CONFIG_ACPI_APEI', if_true: files('ghes.c'), if_false: files('ghes-stub.c'))
 acpi_ss.add(when: 'CONFIG_ACPI_X86', if_true: files('piix4.c', 'pcihp.c'))
+acpi_ss.add(when: 'CONFIG_ACPI_VIOT', if_true: files('viot.c'))
 acpi_ss.add(when: 'CONFIG_ACPI_X86_ICH', if_true: files('ich9.c', 'tco.c'))
 acpi_ss.add(when: 'CONFIG_IPMI', if_true: files('ipmi.c'), if_false: files('ipmi-stub.c'))
 acpi_ss.add(when: 'CONFIG_PC', if_false: files('acpi-x86-stub.c'))
-- 
2.33.0