Convert the compile time check on the CONFIG_VFIO_IGD definition
by a runtime one by calling vfio_igd_builtin(), which check
whether VFIO_IGD is built in a qemu-system binary.

Add stubs to avoid when VFIO_IGD is not built in:

  /usr/bin/ld: libqemu-x86_64-softmmu.a.p/hw_vfio_pci-quirks.c.o: in function `vfio_bar_quirk_setup':
  /usr/bin/ld: ../hw/vfio/pci-quirks.c:1216: undefined reference to `vfio_probe_igd_bar0_quirk'
  /usr/bin/ld: ../hw/vfio/pci-quirks.c:1217: undefined reference to `vfio_probe_igd_bar4_quirk'

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/vfio/pci-quirks.h |  6 ++++++
 hw/vfio/igd-stubs.c  | 20 ++++++++++++++++++++
 hw/vfio/pci-quirks.c |  9 ++++-----
 hw/vfio/meson.build  |  3 +++
 4 files changed, 33 insertions(+), 5 deletions(-)
 create mode 100644 hw/vfio/igd-stubs.c

diff --git a/hw/vfio/pci-quirks.h b/hw/vfio/pci-quirks.h
index fdaa81f00aa..dcdb1962600 100644
--- a/hw/vfio/pci-quirks.h
+++ b/hw/vfio/pci-quirks.h
@@ -13,6 +13,7 @@
 #define HW_VFIO_VFIO_PCI_QUIRKS_H
 
 #include "qemu/osdep.h"
+#include "qom/object.h"
 #include "exec/memop.h"
 
 /*
@@ -71,4 +72,9 @@ extern const MemoryRegionOps vfio_generic_mirror_quirk;
 
 #define TYPE_VFIO_PCI_IGD_LPC_BRIDGE "vfio-pci-igd-lpc-bridge"
 
+static inline bool vfio_igd_builtin(void)
+{
+    return type_is_registered(TYPE_VFIO_PCI_IGD_LPC_BRIDGE);
+}
+
 #endif /* HW_VFIO_VFIO_PCI_QUIRKS_H */
diff --git a/hw/vfio/igd-stubs.c b/hw/vfio/igd-stubs.c
new file mode 100644
index 00000000000..5d4e88aeb1b
--- /dev/null
+++ b/hw/vfio/igd-stubs.c
@@ -0,0 +1,20 @@
+/*
+ * IGD device quirk stubs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * Copyright (C) Linaro, Ltd.
+ */
+
+#include "qemu/osdep.h"
+#include "pci.h"
+
+void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int nr)
+{
+    g_assert_not_reached();
+}
+
+void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
+{
+    g_assert_not_reached();
+}
diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
index c53591fe2ba..22cb35af8cc 100644
--- a/hw/vfio/pci-quirks.c
+++ b/hw/vfio/pci-quirks.c
@@ -11,7 +11,6 @@
  */
 
 #include "qemu/osdep.h"
-#include CONFIG_DEVICES
 #include "exec/memop.h"
 #include "qemu/units.h"
 #include "qemu/log.h"
@@ -1213,10 +1212,10 @@ void vfio_bar_quirk_setup(VFIOPCIDevice *vdev, int nr)
     vfio_probe_nvidia_bar5_quirk(vdev, nr);
     vfio_probe_nvidia_bar0_quirk(vdev, nr);
     vfio_probe_rtl8168_bar2_quirk(vdev, nr);
-#ifdef CONFIG_VFIO_IGD
-    vfio_probe_igd_bar0_quirk(vdev, nr);
-    vfio_probe_igd_bar4_quirk(vdev, nr);
-#endif
+    if (vfio_igd_builtin()) {
+        vfio_probe_igd_bar0_quirk(vdev, nr);
+        vfio_probe_igd_bar4_quirk(vdev, nr);
+    }
 }
 
 void vfio_bar_quirk_exit(VFIOPCIDevice *vdev, int nr)
diff --git a/hw/vfio/meson.build b/hw/vfio/meson.build
index a8939c83865..6ab711d0539 100644
--- a/hw/vfio/meson.build
+++ b/hw/vfio/meson.build
@@ -17,6 +17,9 @@ specific_ss.add_all(when: 'CONFIG_VFIO', if_true: vfio_ss)
 
 system_ss.add(when: 'CONFIG_VFIO_XGMAC', if_true: files('calxeda-xgmac.c'))
 system_ss.add(when: 'CONFIG_VFIO_AMD_XGBE', if_true: files('amd-xgbe.c'))
+system_ss.add(when: 'CONFIG_VFIO_IGD', if_false: files(
+  'igd-stubs.c',
+))
 system_ss.add(when: 'CONFIG_VFIO', if_true: files(
   'helpers.c',
   'container-base.c',
-- 
2.47.1

On 3/9/25 00:09, Philippe Mathieu-Daudé wrote:
> Convert the compile time check on the CONFIG_VFIO_IGD definition
> by a runtime one by calling vfio_igd_builtin(), which check
> whether VFIO_IGD is built in a qemu-system binary.
> 
> Add stubs to avoid when VFIO_IGD is not built in:

I thought we were trying to avoid stubs in QEMU build. Did that change ?


Thanks,

C.


> 
>    /usr/bin/ld: libqemu-x86_64-softmmu.a.p/hw_vfio_pci-quirks.c.o: in function `vfio_bar_quirk_setup':
>    /usr/bin/ld: ../hw/vfio/pci-quirks.c:1216: undefined reference to `vfio_probe_igd_bar0_quirk'
>    /usr/bin/ld: ../hw/vfio/pci-quirks.c:1217: undefined reference to `vfio_probe_igd_bar4_quirk'
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   hw/vfio/pci-quirks.h |  6 ++++++
>   hw/vfio/igd-stubs.c  | 20 ++++++++++++++++++++
>   hw/vfio/pci-quirks.c |  9 ++++-----
>   hw/vfio/meson.build  |  3 +++
>   4 files changed, 33 insertions(+), 5 deletions(-)
>   create mode 100644 hw/vfio/igd-stubs.c
> 
> diff --git a/hw/vfio/pci-quirks.h b/hw/vfio/pci-quirks.h
> index fdaa81f00aa..dcdb1962600 100644
> --- a/hw/vfio/pci-quirks.h
> +++ b/hw/vfio/pci-quirks.h
> @@ -13,6 +13,7 @@
>   #define HW_VFIO_VFIO_PCI_QUIRKS_H
>   
>   #include "qemu/osdep.h"
> +#include "qom/object.h"
>   #include "exec/memop.h"
>   
>   /*
> @@ -71,4 +72,9 @@ extern const MemoryRegionOps vfio_generic_mirror_quirk;
>   
>   #define TYPE_VFIO_PCI_IGD_LPC_BRIDGE "vfio-pci-igd-lpc-bridge"
>   
> +static inline bool vfio_igd_builtin(void)
> +{
> +    return type_is_registered(TYPE_VFIO_PCI_IGD_LPC_BRIDGE);
> +}
> +
>   #endif /* HW_VFIO_VFIO_PCI_QUIRKS_H */
> diff --git a/hw/vfio/igd-stubs.c b/hw/vfio/igd-stubs.c
> new file mode 100644
> index 00000000000..5d4e88aeb1b
> --- /dev/null
> +++ b/hw/vfio/igd-stubs.c
> @@ -0,0 +1,20 @@
> +/*
> + * IGD device quirk stubs
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + * Copyright (C) Linaro, Ltd.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "pci.h"
> +
> +void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int nr)
> +{
> +    g_assert_not_reached();
> +}
> +
> +void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
> +{
> +    g_assert_not_reached();
> +}
> diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
> index c53591fe2ba..22cb35af8cc 100644
> --- a/hw/vfio/pci-quirks.c
> +++ b/hw/vfio/pci-quirks.c
> @@ -11,7 +11,6 @@
>    */
>   
>   #include "qemu/osdep.h"
> -#include CONFIG_DEVICES
>   #include "exec/memop.h"
>   #include "qemu/units.h"
>   #include "qemu/log.h"
> @@ -1213,10 +1212,10 @@ void vfio_bar_quirk_setup(VFIOPCIDevice *vdev, int nr)
>       vfio_probe_nvidia_bar5_quirk(vdev, nr);
>       vfio_probe_nvidia_bar0_quirk(vdev, nr);
>       vfio_probe_rtl8168_bar2_quirk(vdev, nr);
> -#ifdef CONFIG_VFIO_IGD
> -    vfio_probe_igd_bar0_quirk(vdev, nr);
> -    vfio_probe_igd_bar4_quirk(vdev, nr);
> -#endif
> +    if (vfio_igd_builtin()) {
> +        vfio_probe_igd_bar0_quirk(vdev, nr);
> +        vfio_probe_igd_bar4_quirk(vdev, nr);
> +    }
>   }
>   
>   void vfio_bar_quirk_exit(VFIOPCIDevice *vdev, int nr)
> diff --git a/hw/vfio/meson.build b/hw/vfio/meson.build
> index a8939c83865..6ab711d0539 100644
> --- a/hw/vfio/meson.build
> +++ b/hw/vfio/meson.build
> @@ -17,6 +17,9 @@ specific_ss.add_all(when: 'CONFIG_VFIO', if_true: vfio_ss)
>   
>   system_ss.add(when: 'CONFIG_VFIO_XGMAC', if_true: files('calxeda-xgmac.c'))
>   system_ss.add(when: 'CONFIG_VFIO_AMD_XGBE', if_true: files('amd-xgbe.c'))
> +system_ss.add(when: 'CONFIG_VFIO_IGD', if_false: files(
> +  'igd-stubs.c',
> +))
>   system_ss.add(when: 'CONFIG_VFIO', if_true: files(
>     'helpers.c',
>     'container-base.c',

On 10/3/25 08:37, Cédric Le Goater wrote:
> On 3/9/25 00:09, Philippe Mathieu-Daudé wrote:
>> Convert the compile time check on the CONFIG_VFIO_IGD definition
>> by a runtime one by calling vfio_igd_builtin(), which check
>> whether VFIO_IGD is built in a qemu-system binary.
>>
>> Add stubs to avoid when VFIO_IGD is not built in:
> 
> I thought we were trying to avoid stubs in QEMU build. Did that change ?

Hmm so you want remove the VFIO_IGD Kconfig symbol and have it always
builtin with VFIO. It might make sense for quirks, since vfio_realize()
already checks for the VFIO_FEATURE_ENABLE_IGD_OPREGION feature.

I'll see if there aren't other implications I missed.

Thanks,

Phil.

On 3/10/25 21:43, Philippe Mathieu-Daudé wrote:
> On 10/3/25 08:37, Cédric Le Goater wrote:
>> On 3/9/25 00:09, Philippe Mathieu-Daudé wrote:
>>> Convert the compile time check on the CONFIG_VFIO_IGD definition
>>> by a runtime one by calling vfio_igd_builtin(), which check
>>> whether VFIO_IGD is built in a qemu-system binary.
>>>
>>> Add stubs to avoid when VFIO_IGD is not built in:
>>
>> I thought we were trying to avoid stubs in QEMU build. Did that change ?
> 
> Hmm so you want remove the VFIO_IGD Kconfig symbol and have it always
> builtin with VFIO. It might make sense for quirks, since vfio_realize()
> already checks for the VFIO_FEATURE_ENABLE_IGD_OPREGION feature.
> 
> I'll see if there aren't other implications I missed.
> 
> Thanks,
> 
> Phil.

I personally suggest keeping the VFIO_IGD Kconfig symbol to prevent
building IGD-specific code into non x86 target. The change Cedric
mentioned in another reply [1] moves VFIO_FEATURE_ENABLE_IGD_OPREGION
from vfio_realize() to igd.c.

[1] https://lore.kernel.org/qemu-devel/20250306180131.32970-1-tomitamoeko@gmail.com/

Thanks,
Moeko

On 3/10/25 14:43, Philippe Mathieu-Daudé wrote:
> On 10/3/25 08:37, Cédric Le Goater wrote:
>> On 3/9/25 00:09, Philippe Mathieu-Daudé wrote:
>>> Convert the compile time check on the CONFIG_VFIO_IGD definition
>>> by a runtime one by calling vfio_igd_builtin(), which check
>>> whether VFIO_IGD is built in a qemu-system binary.
>>>
>>> Add stubs to avoid when VFIO_IGD is not built in:
>>
>> I thought we were trying to avoid stubs in QEMU build. Did that change ?
> 
> Hmm so you want remove the VFIO_IGD Kconfig symbol and have it always
> builtin with VFIO. It might make sense for quirks, since vfio_realize()
> already checks for the VFIO_FEATURE_ENABLE_IGD_OPREGION feature.

I have explored this option in the past and it's much more work.
Stubs are fine IMO, if we can have them, but I remember someone
telling me (you ?) that we were trying to remove them.


Thanks,

C.



> I'll see if there aren't other implications I missed.
> 
> Thanks,
> 
> Phil.
> 

On 10/3/25 14:51, Cédric Le Goater wrote:
> On 3/10/25 14:43, Philippe Mathieu-Daudé wrote:
>> On 10/3/25 08:37, Cédric Le Goater wrote:
>>> On 3/9/25 00:09, Philippe Mathieu-Daudé wrote:
>>>> Convert the compile time check on the CONFIG_VFIO_IGD definition
>>>> by a runtime one by calling vfio_igd_builtin(), which check
>>>> whether VFIO_IGD is built in a qemu-system binary.
>>>>
>>>> Add stubs to avoid when VFIO_IGD is not built in:
>>>
>>> I thought we were trying to avoid stubs in QEMU build. Did that change ?
>>
>> Hmm so you want remove the VFIO_IGD Kconfig symbol and have it always
>> builtin with VFIO. It might make sense for quirks, since vfio_realize()
>> already checks for the VFIO_FEATURE_ENABLE_IGD_OPREGION feature.
> 
> I have explored this option in the past and it's much more work.
> Stubs are fine IMO, if we can have them, but I remember someone
> telling me (you ?) that we were trying to remove them.

We shouldn't have target-specific stubs.
(currently CONFIG_DEVICES::VFIO_IGD is target specific).

I don't think we can avoid host-specific stubs.

In unified binary, CONFIG_DEVICES disappears, VFIO_IGD
will be handled like host configuration. Although if possible I'd
rather remove VFIO_IGD, unconditionally including all quirks.