Re: [PATCH 2/6] hw/acpi: Add VIOT table

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 10 Aug 2021 10:45:02 +0200
Jean-Philippe Brucker <jean-philippe@linaro.org> wrote:

> 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>


using packed structures for composing ACPI tables is discouraged,
pls use build_append_int_noprefix() API instead. You can look at
build_amd_iommu() as an example.

PS:
Also note field comments format.
/it should be verbatim copy of entry name from respective table in spec/


> ---
>  hw/acpi/viot.h      | 13 +++++++
>  hw/acpi/viot.c      | 82 +++++++++++++++++++++++++++++++++++++++++++++
>  hw/acpi/Kconfig     |  4 +++
>  hw/acpi/meson.build |  1 +
>  4 files changed, 100 insertions(+)
>  create mode 100644 hw/acpi/viot.h
>  create mode 100644 hw/acpi/viot.c
> 
> 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..5cd10e9553
> --- /dev/null
> +++ b/hw/acpi/viot.c
> @@ -0,0 +1,82 @@
> +/*
> + * 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"
> +
> +/* Build PCI range for a given PCI host bridge */
> +static int viot_host_bridges(Object *obj, void *opaque)
> +{
> +    GArray *pci_range_blob = opaque;
> +
> +    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);
> +
> +            AcpiViotPciRange pci_range = {
> +                .type = ACPI_VIOT_NODE_PCI_RANGE,
> +                .length = cpu_to_le16(sizeof(pci_range)),
> +                .bdf_start = cpu_to_le16(PCI_BUILD_BDF(min_bus, 0)),
> +                .bdf_end = cpu_to_le16(PCI_BUILD_BDF(max_bus, 0xff)),
> +                .endpoint_start = cpu_to_le32(PCI_BUILD_BDF(min_bus, 0)),
> +            };
> +
> +            g_array_append_val(pci_range_blob, pci_range);
> +        }
> +    }
> +
> +    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)
> +{
> +    int i;
> +    AcpiViot *viot;
> +    AcpiViotPciRange *pci_range;
> +    AcpiViotVirtioIommuPci *viommu;
> +    int viommu_off = sizeof(*viot);
> +    int viot_start = table_data->len;
> +    GArray *pci_ranges = g_array_new(false, true, sizeof(*pci_range));
> +
> +    viot = acpi_data_push(table_data, sizeof(*viot));
> +    viot->node_offset = cpu_to_le16(viommu_off);
> +
> +    viommu = acpi_data_push(table_data, sizeof(*viommu));
> +    viommu->type = ACPI_VIOT_NODE_VIRTIO_IOMMU_PCI;
> +    viommu->length = cpu_to_le16(sizeof(*viommu));
> +    viommu->bdf = cpu_to_le16(virtio_iommu_bdf);
> +
> +    /* Build the list of PCI ranges that this viommu manages */
> +    object_child_foreach_recursive(object_get_root(), viot_host_bridges,
> +                                   pci_ranges);
> +
> +    for (i = 0; i < pci_ranges->len; i++) {
> +        pci_range = &g_array_index(pci_ranges, AcpiViotPciRange, i);
> +        pci_range->output_node = cpu_to_le16(viommu_off);
> +    }
> +    viot->node_count = cpu_to_le16(pci_ranges->len + 1);
> +
> +    g_array_append_vals(table_data, pci_ranges->data,
> +                        pci_ranges->len * sizeof(*pci_range));
> +    g_array_free(pci_ranges, 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/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/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'))