Re: [PATCH v2 3/5] vfio/igd: refactor vfio_probe_igd_bar4_quirk() into pci config quirk

["Cédric Le Goater" <clg@redhat.com>]

Hello Tomita,

On 1/24/25 20:12, Tomita Moeko wrote:
> The actual IO BAR4 write quirk in vfio_probe_igd_bar4_quirk() was
> removed in previous change, leaving the function not matching its name,
> so move it into the newly introduced vfio_config_quirk_setup(). There
> is no functional change in this commit. If any failure occurs, the
> function simply returns and proceeds.
> 
> Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
> ---
>   hw/vfio/igd.c        | 31 +++++++++++++++++--------------
>   hw/vfio/pci-quirks.c |  6 +++++-
>   hw/vfio/pci.h        |  2 +-
>   3 files changed, 23 insertions(+), 16 deletions(-)
> 
> diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
> index ca3a32f4f2..376a26fbae 100644
> --- a/hw/vfio/igd.c
> +++ b/hw/vfio/igd.c
> @@ -359,7 +359,8 @@ void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int nr)
>       QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, bdsm_quirk, next);
>   }
>   
> -void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
> +bool vfio_probe_igd_config_quirk(VFIOPCIDevice *vdev,
> +                                 Error **errp G_GNUC_UNUSED)

Adding an 'Error **' parameter is in improvement indeed. All the error_report
of this routine need to be converted too.

>   {
>       g_autofree struct vfio_region_info *rom = NULL;
>       g_autofree struct vfio_region_info *opregion = NULL;
> @@ -378,10 +379,10 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>        * PCI bus address.
>        */
>       if (!vfio_pci_is(vdev, PCI_VENDOR_ID_INTEL, PCI_ANY_ID) ||
> -        !vfio_is_vga(vdev) || nr != 4 ||
> +        !vfio_is_vga(vdev) ||
>           &vdev->pdev != pci_find_device(pci_device_root_bus(&vdev->pdev),
>                                          0, PCI_DEVFN(0x2, 0))) {
> -        return;
> +        return true;
>       }
>   
>       /*
> @@ -395,7 +396,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>                                              "vfio-pci-igd-lpc-bridge")) {
>           error_report("IGD device %s cannot support legacy mode due to existing "
>                        "devices at address 1f.0", vdev->vbasedev.name);
> -        return;
> +        return true;

if there is an error_report, why is this returning true ? It should be false.
  
>       }
>   
>       /*
> @@ -407,7 +408,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>       if (gen == -1) {
>           error_report("IGD device %s is unsupported in legacy mode, "
>                        "try SandyBridge or newer", vdev->vbasedev.name);
> -        return;
> +        return true;

same here and else where.

>       }
>   
>       /*
> @@ -420,7 +421,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>       if ((ret || !rom->size) && !vdev->pdev.romfile) {
>           error_report("IGD device %s has no ROM, legacy mode disabled",
>                        vdev->vbasedev.name);
> -        return;
> +        return true;
>       }
>   
>       /*
> @@ -431,7 +432,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>           error_report("IGD device %s hotplugged, ROM disabled, "
>                        "legacy mode disabled", vdev->vbasedev.name);
>           vdev->rom_read_failed = true;
> -        return;
> +        return true;
>       }
>   
>       /*
> @@ -444,7 +445,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>       if (ret) {
>           error_report("IGD device %s does not support OpRegion access,"
>                        "legacy mode disabled", vdev->vbasedev.name);
> -        return;
> +        return true;
>       }
>   
>       ret = vfio_get_dev_region_info(&vdev->vbasedev,
> @@ -453,7 +454,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>       if (ret) {
>           error_report("IGD device %s does not support host bridge access,"
>                        "legacy mode disabled", vdev->vbasedev.name);
> -        return;
> +        return true;
>       }
>   
>       ret = vfio_get_dev_region_info(&vdev->vbasedev,
> @@ -462,7 +463,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>       if (ret) {
>           error_report("IGD device %s does not support LPC bridge access,"
>                        "legacy mode disabled", vdev->vbasedev.name);
> -        return;
> +        return true;
>       }
>   
>       gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, 4);
> @@ -476,7 +477,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>           error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
>           error_report("IGD device %s failed to enable VGA access, "
>                        "legacy mode disabled", vdev->vbasedev.name);
> -        return;
> +        return true;
>       }
>   
>       /* Create our LPC/ISA bridge */
> @@ -484,7 +485,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>       if (ret) {
>           error_report("IGD device %s failed to create LPC bridge, "
>                        "legacy mode disabled", vdev->vbasedev.name);
> -        return;
> +        return true;
>       }
>   
>       /* Stuff some host values into the VM PCI host bridge */
> @@ -492,14 +493,14 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>       if (ret) {
>           error_report("IGD device %s failed to modify host bridge, "
>                        "legacy mode disabled", vdev->vbasedev.name);
> -        return;
> +        return true;
>       }
>   
>       /* Setup OpRegion access */
>       if (!vfio_pci_igd_opregion_init(vdev, opregion, &err)) {
>           error_append_hint(&err, "IGD legacy mode disabled\n");
>           error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
> -        return;
> +        return true;
>       }
>   
>       /*
> @@ -561,4 +562,6 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
>   
>       trace_vfio_pci_igd_bdsm_enabled(vdev->vbasedev.name,
>                                       (ggms_size + gms_size) / MiB);
> +
> +    return true;
>   }
> diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
> index c40e3ca88f..b8379cb512 100644
> --- a/hw/vfio/pci-quirks.c
> +++ b/hw/vfio/pci-quirks.c
> @@ -1169,6 +1169,11 @@ bool vfio_pci_igd_opregion_init(VFIOPCIDevice *vdev,
>    */
>   bool vfio_config_quirk_setup(VFIOPCIDevice *vdev, Error **errp)
>   {
> +#ifdef CONFIG_VFIO_IGD

oh. We try to avoid such ifdef in QEMU. Only very specific and high level
configs are discarded at compile time (KVM, LINUX, etc).

One way to adress this case, would be to use QOM. Example below :

  
Declare a base class :
     
     #define TYPE_VFIO_PCI_QUIRK_PROVIDER "vfio-pci-quirk-provider"
     
     OBJECT_DECLARE_TYPE(VFIOPCIQuirkProvider, VFIOPCIQuirkProviderClass,
                         VFIO_PCI_QUIRK_PROVIDER)
     
     struct VFIOPCIQuirkProviderClass {
         ObjectClass parent;
     
         bool (*probe)(VFIOPCIDevice *vdev, Error **errp);
         bool (*setup)(VFIOPCIDevice *vdev, Error **errp);
     };
     
     static const TypeInfo vfio_pci_quirk_info = {
         .name = TYPE_VFIO_PCI_QUIRK_PROVIDER,
         .parent = TYPE_OBJECT,
         .class_size = sizeof(VFIOPCIQuirkClass),
         .abstract = true,
     };
     
     static void register_vfio_pci_quirk_type(void)
     {
         type_register_static(&vfio_pci_quirk_info);
     }
     
     type_init(register_vfio_pci_quirk_type)


Declare one for IGD
     
     static void vfio_pci_quirk_igd_class_init(ObjectClass *klass, void *data)
     {
         VFIOPCIQuirkClass* vpqc = VFIO_PCI_QUIRK_PROVIDER_CLASS(klass);
     
         vpqc->setup = vfio_probe_igd_quirk_probe;
         vpqc->probe = vfio_probe_igd_quirk_probe;
     }
     
     static const TypeInfo vfio_pci_quirk_igd_info = {
         .name = TYPE_VFIO_PCI_QUIRK_PROVIDER "-igd",
         .parent = TYPE_VFIO_PCI_QUIRK_PROVIDER,
         .class_init = vfio_pci_quirk_igd_class_init,
         .class_size = sizeof(VFIOPCIQuirkClass),
     };
     
     static void vfio_pci_quirk_igd_register_types(void)
     {
         type_register_static(&vfio_pci_quirk_igd_info);
     }
     
     type_init(vfio_pci_quirk_igd_register_types)


and in the common part, loop on all the classes to probe and setup :


     static void vfio_pci_quirk_class_foreach(ObjectClass *klass, void *opaque)
     {
         VFIOPCIQuirkProviderClass* vpqc = VFIO_PCI_QUIRK_PROVIDER_CLASS(klass);
         Error *local_err = NULL;
     
         vpqc->setup(opaque, &local_err);
     }
     
     bool vfio_config_quirk_setup(VFIOPCIDevice *vdev, Error **errp)
     {
         object_class_foreach(vfio_pci_quirk_class_foreach,
                              TYPE_VFIO_PCI_QUIRK_PROVIDER, false, vdev);
        ...




Thanks,

C.