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Re: [Qemu-devel] [PATCH v2 1/2] Add PCI bus listener interface
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/2] Add PCI bus listener interface |
Date: |
Tue, 14 Oct 2014 12:53:42 +0300 |
On Mon, Oct 13, 2014 at 01:52:46PM +0100, Paul Durrant wrote:
> The Xen ioreq-server API, introduced in Xen 4.5, requires that PCI device
> models explicitly register with Xen for config space accesses. This patch
> adds a PCI bus listener interface which can be used by the Xen interface
> code to monitor PCI buses for arrival and departure of devices.
>
> Signed-off-by: Paul Durrant <address@hidden>
> Cc: Michael S. Tsirkin <address@hidden>
> Cc: Paolo Bonzini <address@hidden>
> Cc: Andreas Faerber <address@hidden>
> Cc: Thomas Huth <address@hidden>
> Cc: Peter Crosthwaite <address@hidden>
> Cc: Christian Borntraeger <address@hidden>
Do you really need multiple notifiers?
In any case, I think such a mechanism makes more sense on QOM level:
we have APIs to find objects of a given class and/or at a given path,
why not a mechanism to get notified when said objects are added/removed.
> ---
> hw/pci/pci.c | 65
> +++++++++++++++++++++++++++++++++++++++++++++++
> include/hw/pci/pci.h | 9 +++++++
> include/qemu/typedefs.h | 1 +
> 3 files changed, 75 insertions(+)
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 6ce75aa..53c955d 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -122,6 +122,66 @@ static uint16_t pci_default_sub_device_id =
> PCI_SUBDEVICE_ID_QEMU;
>
> static QLIST_HEAD(, PCIHostState) pci_host_bridges;
>
> +static QTAILQ_HEAD(pci_listeners, PCIListener) pci_listeners
> + = QTAILQ_HEAD_INITIALIZER(pci_listeners);
> +
> +enum ListenerDirection { Forward, Reverse };
> +
> +#define PCI_LISTENER_CALL(_callback, _direction, _args...) \
> + do { \
> + PCIListener *_listener; \
> + \
> + switch (_direction) { \
> + case Forward: \
> + QTAILQ_FOREACH(_listener, &pci_listeners, link) { \
> + if (_listener->_callback) { \
> + _listener->_callback(_listener, ##_args); \
> + } \
> + } \
> + break; \
> + case Reverse: \
> + QTAILQ_FOREACH_REVERSE(_listener, &pci_listeners, \
> + pci_listeners, link) { \
> + if (_listener->_callback) { \
> + _listener->_callback(_listener, ##_args); \
> + } \
> + } \
> + break; \
> + default: \
> + abort(); \
> + } \
> + } while (0)
> +
> +static int pci_listener_add(DeviceState *dev, void *opaque)
> +{
> + if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
> + PCIDevice *pci_dev = PCI_DEVICE(dev);
> +
> + PCI_LISTENER_CALL(device_add, Forward, pci_dev);
> + }
> +
> + return 0;
> +}
> +
> +void pci_listener_register(PCIListener *listener)
> +{
> + PCIHostState *host;
> +
> + QTAILQ_INSERT_TAIL(&pci_listeners, listener, link);
> +
> + QLIST_FOREACH(host, &pci_host_bridges, next) {
> + PCIBus *bus = host->bus;
> +
> + qbus_walk_children(&bus->qbus, NULL, NULL, pci_listener_add,
> + NULL, NULL);
> + }
> +}
> +
> +void pci_listener_unregister(PCIListener *listener)
> +{
> + QTAILQ_REMOVE(&pci_listeners, listener, link);
> +}
> +
> static int pci_bar(PCIDevice *d, int reg)
> {
> uint8_t type;
> @@ -795,6 +855,8 @@ static void pci_config_free(PCIDevice *pci_dev)
>
> static void do_pci_unregister_device(PCIDevice *pci_dev)
> {
> + PCI_LISTENER_CALL(device_del, Reverse, pci_dev);
> +
> pci_dev->bus->devices[pci_dev->devfn] = NULL;
> pci_config_free(pci_dev);
>
> @@ -878,6 +940,9 @@ static PCIDevice *do_pci_register_device(PCIDevice
> *pci_dev, PCIBus *bus,
> pci_dev->config_write = config_write;
> bus->devices[devfn] = pci_dev;
> pci_dev->version_id = 2; /* Current pci device vmstate version */
> +
> + PCI_LISTENER_CALL(device_add, Forward, pci_dev);
> +
> return pci_dev;
> }
>
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index c352c7b..6c21b37 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -303,6 +303,15 @@ struct PCIDevice {
> MSIVectorPollNotifier msix_vector_poll_notifier;
> };
>
> +struct PCIListener {
> + void (*device_add)(PCIListener *listener, PCIDevice *pci_dev);
> + void (*device_del)(PCIListener *listener, PCIDevice *pci_dev);
> + QTAILQ_ENTRY(PCIListener) link;
> +};
> +
> +void pci_listener_register(PCIListener *listener);
> +void pci_listener_unregister(PCIListener *listener);
> +
> void pci_register_bar(PCIDevice *pci_dev, int region_num,
> uint8_t attr, MemoryRegion *memory);
> void pci_register_vga(PCIDevice *pci_dev, MemoryRegion *mem,
> diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
> index 04df51b..2b974c6 100644
> --- a/include/qemu/typedefs.h
> +++ b/include/qemu/typedefs.h
> @@ -54,6 +54,7 @@ typedef struct PCIHostState PCIHostState;
> typedef struct PCIExpressHost PCIExpressHost;
> typedef struct PCIBus PCIBus;
> typedef struct PCIDevice PCIDevice;
> +typedef struct PCIListener PCIListener;
> typedef struct PCIExpressDevice PCIExpressDevice;
> typedef struct PCIBridge PCIBridge;
> typedef struct PCIEAERMsg PCIEAERMsg;
> --
> 1.7.10.4