Re: [PATCH v3 3/3] hw: Set virtio-iommu aw-bits default value on pc_q35 and arm virt

[Cédric Le Goater]

On 2/8/24 11:10, Eric Auger wrote:
> Currently the default input range can extend to 64 bits. On x86,
> when the virtio-iommu protects vfio devices, the physical iommu
> may support only 39 bits. Let's set the default to 39, as done
> for the intel-iommu. On ARM we set 48b as a default (matching
> SMMUv3 SMMU_IDR5.VAX == 0).
>
> We use hw_compat_8_2 to handle the compatibility for machines
> before 9.0 which used to have a virtio-iommu default input range
> of 64 bits.
>
> Of course if aw-bits is set from the command line, the default
> is overriden.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> Tested-by: Yanghang Liu<yanghliu@redhat.com>

Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.

> ---
>
> v2 -> v3:
> - collected Zhenzhong's R-b
> - use &error_abort instead of NULL error handle
>    on object_property_get_uint() call (Cédric)
> - use VTD_HOST_AW_39BIT (Cédric)
>
> v1 -> v2:
> - set aw-bits to 48b on ARM
> - use hw_compat_8_2 to handle the compat for older machines
>    which used 64b as a default
> ---
>   hw/arm/virt.c            | 6 ++++++
>   hw/core/machine.c        | 5 ++++-
>   hw/i386/pc.c             | 6 ++++++
>   hw/virtio/virtio-iommu.c | 2 +-
>   4 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 368c2a415a..0994f2a560 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -2716,10 +2716,16 @@ static void 
> virt_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
>       } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
>           virtio_md_pci_pre_plug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), 
> errp);
>       } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
> +        uint8_t aw_bits = object_property_get_uint(OBJECT(dev),
> +                                                   "aw-bits", &error_abort);
>           hwaddr db_start = 0, db_end = 0;
>           QList *reserved_regions;
>           char *resv_prop_str;
>   
> +        if (!aw_bits) {
> +            qdev_prop_set_uint8(dev, "aw-bits", 48);
> +        }
> +
>           if (vms->iommu != VIRT_IOMMU_NONE) {
>               error_setg(errp, "virt machine does not support multiple IOMMUs");
>               return;
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index fb5afdcae4..70ac96954c 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -30,9 +30,12 @@
>   #include "exec/confidential-guest-support.h"
>   #include "hw/virtio/virtio-pci.h"
>   #include "hw/virtio/virtio-net.h"
> +#include "hw/virtio/virtio-iommu.h"
>   #include "audio/audio.h"
>   
> -GlobalProperty hw_compat_8_2[] = {};
> +GlobalProperty hw_compat_8_2[] = {
> +    { TYPE_VIRTIO_IOMMU_PCI, "aw-bits", "64" },
> +};
>   const size_t hw_compat_8_2_len = G_N_ELEMENTS(hw_compat_8_2);
>   
>   GlobalProperty hw_compat_8_1[] = {
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 196827531a..ee2d379c90 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1456,6 +1456,8 @@ static void pc_machine_device_pre_plug_cb(HotplugHandler 
> *hotplug_dev,
>       } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
>           virtio_md_pci_pre_plug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), 
> errp);
>       } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
> +        uint8_t aw_bits = object_property_get_uint(OBJECT(dev),
> +                                                   "aw-bits", &error_abort);
>           /* 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);
> @@ -1464,6 +1466,10 @@ static void pc_machine_device_pre_plug_cb(HotplugHandler 
> *hotplug_dev,
>           qlist_append_str(reserved_regions, resv_prop_str);
>           qdev_prop_set_array(dev, "reserved-regions", reserved_regions);
>   
> +        if (!aw_bits) {
> +            qdev_prop_set_uint8(dev, "aw-bits", VTD_HOST_AW_39BIT);
> +        }
> +
>           g_free(resv_prop_str);
>       }
>   
> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
> index 7870bdbeee..c468e9b13b 100644
> --- a/hw/virtio/virtio-iommu.c
> +++ b/hw/virtio/virtio-iommu.c
> @@ -1529,7 +1529,7 @@ static Property virtio_iommu_properties[] = {
>       DEFINE_PROP_LINK("primary-bus", VirtIOIOMMU, primary_bus,
>                        TYPE_PCI_BUS, PCIBus *),
>       DEFINE_PROP_BOOL("boot-bypass", VirtIOIOMMU, boot_bypass, true),
> -    DEFINE_PROP_UINT8("aw-bits", VirtIOIOMMU, aw_bits, 64),
> +    DEFINE_PROP_UINT8("aw-bits", VirtIOIOMMU, aw_bits, 0),
>       DEFINE_PROP_END_OF_LIST(),
>   };
>