Re: [PATCH v3 3/7] arm/virt: Use virtio-md-pci (un)plug functions

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jul 10, 2023 at 12:07:10PM +0200, David Hildenbrand wrote:
> Let's use our new helper functions. Note that virtio-pmem-pci is not
> enabled for arm and, therefore, not compiled in.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  hw/arm/virt.c | 81 ++++++++-------------------------------------------
>  1 file changed, 12 insertions(+), 69 deletions(-)
> 
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 8a4c663735..4ae1996d37 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -73,11 +73,10 @@
>  #include "hw/arm/smmuv3.h"
>  #include "hw/acpi/acpi.h"
>  #include "target/arm/internals.h"
> -#include "hw/mem/memory-device.h"
>  #include "hw/mem/pc-dimm.h"
>  #include "hw/mem/nvdimm.h"
>  #include "hw/acpi/generic_event_device.h"
> -#include "hw/virtio/virtio-mem-pci.h"
> +#include "hw/virtio/virtio-md-pci.h"
>  #include "hw/virtio/virtio-iommu.h"
>  #include "hw/char/pl011.h"
>  #include "qemu/guest-random.h"
> @@ -2740,64 +2739,6 @@ static void virt_memory_plug(HotplugHandler *hotplug_dev,
>                           dev, &error_abort);
>  }
>  
> -static void virt_virtio_md_pci_pre_plug(HotplugHandler *hotplug_dev,
> -                                        DeviceState *dev, Error **errp)
> -{
> -    HotplugHandler *hotplug_dev2 = qdev_get_bus_hotplug_handler(dev);
> -    Error *local_err = NULL;
> -
> -    if (!hotplug_dev2 && dev->hotplugged) {
> -        /*
> -         * Without a bus hotplug handler, we cannot control the plug/unplug
> -         * order. We should never reach this point when hotplugging on ARM.
> -         * However, it's nice to add a safety net, similar to what we have
> -         * on x86.
> -         */
> -        error_setg(errp, "hotplug of virtio based memory devices not supported"
> -                   " on this bus.");
> -        return;
> -    }
> -    /*
> -     * First, see if we can plug this memory device at all. If that
> -     * succeeds, branch of to the actual hotplug handler.
> -     */
> -    memory_device_pre_plug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev), NULL,
> -                           &local_err);
> -    if (!local_err && hotplug_dev2) {
> -        hotplug_handler_pre_plug(hotplug_dev2, dev, &local_err);
> -    }
> -    error_propagate(errp, local_err);
> -}
> -
> -static void virt_virtio_md_pci_plug(HotplugHandler *hotplug_dev,
> -                                    DeviceState *dev, Error **errp)
> -{
> -    HotplugHandler *hotplug_dev2 = qdev_get_bus_hotplug_handler(dev);
> -    Error *local_err = NULL;
> -
> -    /*
> -     * Plug the memory device first and then branch off to the actual
> -     * hotplug handler. If that one fails, we can easily undo the memory
> -     * device bits.
> -     */
> -    memory_device_plug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev));
> -    if (hotplug_dev2) {
> -        hotplug_handler_plug(hotplug_dev2, dev, &local_err);
> -        if (local_err) {
> -            memory_device_unplug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev));
> -        }
> -    }
> -    error_propagate(errp, local_err);
> -}
> -
> -static void virt_virtio_md_pci_unplug_request(HotplugHandler *hotplug_dev,
> -                                              DeviceState *dev, Error **errp)
> -{
> -    /* We don't support hot unplug of virtio based memory devices */
> -    error_setg(errp, "virtio based memory devices cannot be unplugged.");
> -}
> -
> -
>  static void virt_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
>                                              DeviceState *dev, Error **errp)
>  {
> @@ -2805,8 +2746,8 @@ static void virt_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
>  
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>          virt_memory_pre_plug(hotplug_dev, dev, errp);
> -    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
> -        virt_virtio_md_pci_pre_plug(hotplug_dev, dev, errp);
> +    } 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)) {
>          hwaddr db_start = 0, db_end = 0;
>          char *resv_prop_str;
> @@ -2855,12 +2796,11 @@ static void virt_machine_device_plug_cb(HotplugHandler *hotplug_dev,
>                                       SYS_BUS_DEVICE(dev));
>          }
>      }
> +
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>          virt_memory_plug(hotplug_dev, dev, errp);
> -    }
> -
> -    if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
> -        virt_virtio_md_pci_plug(hotplug_dev, dev, errp);
> +    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
> +        virtio_md_pci_plug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), errp);
>      }
>  
>      if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {


How is this supposed to link if virtio-md is disabled at compile time?

Indeed I see this on mingw:

FAILED: qemu-system-aarch64.exe 
i686-w64-mingw32-gcc -m32 @qemu-system-aarch64.exe.rsp
/usr/lib/gcc/i686-w64-mingw32/12.2.1/../../../../i686-w64-mingw32/bin/ld: libqemu-aarch64-softmmu.fa.p/hw_arm_virt.c.obj: in function `virt_machine_device_plug_cb':
/scm/qemu-mingw32-build/../qemu/hw/arm/virt.c:2803: undefined reference to `virtio_md_pci_plug'
/usr/lib/gcc/i686-w64-mingw32/12.2.1/../../../../i686-w64-mingw32/bin/ld: libqemu-aarch64-softmmu.fa.p/hw_arm_virt.c.obj: in function `virt_machine_device_unplug_request_cb':
/scm/qemu-mingw32-build/../qemu/hw/arm/virt.c:2859: undefined reference to `virtio_md_pci_unplug_request'
/usr/lib/gcc/i686-w64-mingw32/12.2.1/../../../../i686-w64-mingw32/bin/ld: libqemu-aarch64-softmmu.fa.p/hw_arm_virt.c.obj: in function `virt_machine_device_unplug_cb':
/scm/qemu-mingw32-build/../qemu/hw/arm/virt.c:2873: undefined reference to `virtio_md_pci_unplug'
/usr/lib/gcc/i686-w64-mingw32/12.2.1/../../../../i686-w64-mingw32/bin/ld: libqemu-aarch64-softmmu.fa.p/hw_arm_virt.c.obj: in function `virt_machine_device_pre_plug_cb':
/scm/qemu-mingw32-build/../qemu/hw/arm/virt.c:2750: undefined reference to `virtio_md_pci_pre_plug'
collect2: error: ld returned 1 exit status
[795/3838] Linking target qemu-system-aarch64w.exe
FAILED: qemu-system-aarch64w.exe 
i686-w64-mingw32-gcc -m32 @qemu-system-aarch64w.exe.rsp
/usr/lib/gcc/i686-w64-mingw32/12.2.1/../../../../i686-w64-mingw32/bin/ld: libqemu-aarch64-softmmu.fa.p/hw_arm_virt.c.obj: in function `virt_machine_device_plug_cb':
/scm/qemu-mingw32-build/../qemu/hw/arm/virt.c:2803: undefined reference to `virtio_md_pci_plug'
/usr/lib/gcc/i686-w64-mingw32/12.2.1/../../../../i686-w64-mingw32/bin/ld: libqemu-aarch64-softmmu.fa.p/hw_arm_virt.c.obj: in function `virt_machine_device_unplug_request_cb':
/scm/qemu-mingw32-build/../qemu/hw/arm/virt.c:2859: undefined reference to `virtio_md_pci_unplug_request'
/usr/lib/gcc/i686-w64-mingw32/12.2.1/../../../../i686-w64-mingw32/bin/ld: libqemu-aarch64-softmmu.fa.p/hw_arm_virt.c.obj: in function `virt_machine_device_unplug_cb':
/scm/qemu-mingw32-build/../qemu/hw/arm/virt.c:2873: undefined reference to `virtio_md_pci_unplug'
/usr/lib/gcc/i686-w64-mingw32/12.2.1/../../../../i686-w64-mingw32/bin/ld: libqemu-aarch64-softmmu.fa.p/hw_arm_virt.c.obj: in function `virt_machine_device_pre_plug_cb':
/scm/qemu-mingw32-build/../qemu/hw/arm/virt.c:2750: undefined reference to `virtio_md_pci_pre_plug'
collect2: error: ld returned 1 exit status
[796/3838] Compiling C object libqemu-cris-softmmu.fa.p/fpu_softfloat.c.obj
[797/3838] Compiling C object libqemu-hppa-softmmu.fa.p/fpu_softfloat.c.obj
ninja: build stopped: subcommand failed.
make: *** [Makefile:162: run-ninja] Error 1




> @@ -2915,8 +2855,9 @@ static void virt_machine_device_unplug_request_cb(HotplugHandler *hotplug_dev,
>  {
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>          virt_dimm_unplug_request(hotplug_dev, dev, errp);
> -    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
> -        virt_virtio_md_pci_unplug_request(hotplug_dev, dev, errp);
> +    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
> +        virtio_md_pci_unplug_request(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev),
> +                                     errp);
>      } else {
>          error_setg(errp, "device unplug request for unsupported device"
>                     " type: %s", object_get_typename(OBJECT(dev)));
> @@ -2928,6 +2869,8 @@ static void virt_machine_device_unplug_cb(HotplugHandler *hotplug_dev,
>  {
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>          virt_dimm_unplug(hotplug_dev, dev, errp);
> +    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
> +        virtio_md_pci_unplug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), errp);
>      } else {
>          error_setg(errp, "virt: device unplug for unsupported device"
>                     " type: %s", object_get_typename(OBJECT(dev)));
> @@ -2941,7 +2884,7 @@ static HotplugHandler *virt_machine_get_hotplug_handler(MachineState *machine,
>  
>      if (device_is_dynamic_sysbus(mc, dev) ||
>          object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) ||
> -        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI) ||
> +        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI) ||
>          object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
>          return HOTPLUG_HANDLER(machine);
>      }
> -- 
> 2.41.0