Re: [PATCH v5 04/12] hw/i386/pc: Allow instantiating a virtio-iommu device

[Igor Mammedov]

On Wed, 20 Oct 2021 18:27:38 +0100
Jean-Philippe Brucker <jean-philippe@linaro.org> wrote:

> 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.

shouldn't above be "IO remapping"?

> 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>
> Tested-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

Reviewed-by: Igor Mammedov <imammedo@redhat.com>
> ---
>  hw/i386/acpi-build.c | 10 +++++++++-
>  hw/i386/pc.c         | 16 +++++++++++++++-
>  hw/i386/Kconfig      |  1 +
>  3 files changed, 25 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index ab49e799ff..3ca6cc8118 100644
> --- a/hw/i386/acpi-build.c
> +++ b/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,
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index fcbf328e8d..f47f7866c7 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"
> @@ -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);
>      }
> diff --git a/hw/i386/Kconfig b/hw/i386/Kconfig
> index 962d2c981b..d22ac4a4b9 100644
> --- a/hw/i386/Kconfig
> +++ b/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