Re: [Qemu-devel] [PATCH v6 3/7] hw/pci-bridge: introduce "hotplug" property

[Michael S. Tsirkin]

On Wed, Jun 17, 2015 at 03:55:32PM +0200, Laszlo Ersek wrote:
> On 06/17/15 15:42, Michael S. Tsirkin wrote:
> > On Wed, Jun 17, 2015 at 02:45:01PM +0200, Laszlo Ersek wrote:
> >> In the PCI expander bridge, we will want to disable those features of
> >> pci-bridge that relate to SHPC (standard hotplug controller):
> >>
> >> - SHPC bar and underlying MemoryRegion
> >> - interrupt (INTx or MSI)
> >> - effective hotplug callbacks
> >> - other SHPC hooks (initialization, cleanup, migration etc)
> >>
> >> Introduce a new feature bit in the PCIBridgeDev.flags field, and turn off
> >> the above if the bit is explicitly cleared.
> >>
> >> Suggested-by: Michael S. Tsirkin <address@hidden>
> >> Cc: Michael S. Tsirkin <address@hidden>
> >> Cc: Marcel Apfelbaum <address@hidden>
> >> Signed-off-by: Laszlo Ersek <address@hidden>
> > 
> > 
> > I think I would prefer naming the property "shpc".
> > In particular ACPI hotplug still works fine.
> 
> Will do.
> 
> Are you okay with the flag's name, PCI_BRIDGE_DEV_F_HOTPLUG? If not,
> what would be your preference?

PCI_BRIDGE_DEV_F_SHPC_REQ

Also add macro for "shpc" property string to avoid duplication.
Also clear msi explicitly - no need for that to depend on shpc.

> Should I also rename the helper function hotplug_enabled() to
> shpc_enabled()?

It should be tested only once - before shpc is initialized.
All other users should test QEMU_PCI_CAP_SHPC - if you like,
using a helper shpc_present.

> 
> Thanks
> Laszlo
> 
> > 
> > 
> >> ---
> >>
> >> Notes:
> >>     v6:
> >>     - new in v6 (replaces "hw/pci-bridge: create interrupt-less,
> >>       hotplug-less bridge for PXB" from v5) [Michael]
> >>     - I tested migration-to-file and migration-from-file, with a single PXB
> >>       behind which a virtio-scsi HBA lived
> >>     - No idea how to test the hotplug callbacks. I tried the device_add and
> >>       device_del HMP commands with a virtio-scsi HBA behind the PXB, and 
> >> the
> >>       monitor reports no error at all; the callbacks don't seem to be
> >>       reached.
> >>     - Retested with windows 2012; it works
> >>
> >>  hw/pci-bridge/pci_bridge_dev.c | 90 
> >> ++++++++++++++++++++++++++++++++++++------
> >>  1 file changed, 78 insertions(+), 12 deletions(-)
> >>
> >> diff --git a/hw/pci-bridge/pci_bridge_dev.c 
> >> b/hw/pci-bridge/pci_bridge_dev.c
> >> index d697c7b..a0a1ce9 100644
> >> --- a/hw/pci-bridge/pci_bridge_dev.c
> >> +++ b/hw/pci-bridge/pci_bridge_dev.c
> >> @@ -40,10 +40,16 @@ struct PCIBridgeDev {
> >>      MemoryRegion bar;
> >>      uint8_t chassis_nr;
> >>  #define PCI_BRIDGE_DEV_F_MSI_REQ 0
> >> +#define PCI_BRIDGE_DEV_F_HOTPLUG 1
> >>      uint32_t flags;
> >>  };
> >>  typedef struct PCIBridgeDev PCIBridgeDev;
> >>  
> >> +static inline bool hotplug_enabled(const PCIBridgeDev *bridge_dev)
> >> +{
> >> +    return !!(bridge_dev->flags & (1u << PCI_BRIDGE_DEV_F_HOTPLUG));
> >> +}
> >> +
> >>  static int pci_bridge_dev_initfn(PCIDevice *dev)
> >>  {
> >>      PCIBridge *br = PCI_BRIDGE(dev);
> >> @@ -54,16 +60,26 @@ static int pci_bridge_dev_initfn(PCIDevice *dev)
> >>      if (err) {
> >>          goto bridge_error;
> >>      }
> >> -    dev->config[PCI_INTERRUPT_PIN] = 0x1;
> >> -    memory_region_init(&bridge_dev->bar, OBJECT(dev), "shpc-bar", 
> >> shpc_bar_size(dev));
> >> -    err = shpc_init(dev, &br->sec_bus, &bridge_dev->bar, 0);
> >> -    if (err) {
> >> -        goto shpc_error;
> >> +
> >> +    if (hotplug_enabled(bridge_dev)) {
> >> +        dev->config[PCI_INTERRUPT_PIN] = 0x1;
> >> +        memory_region_init(&bridge_dev->bar, OBJECT(dev), "shpc-bar",
> >> +                           shpc_bar_size(dev));
> >> +        err = shpc_init(dev, &br->sec_bus, &bridge_dev->bar, 0);
> >> +        if (err) {
> >> +            goto shpc_error;
> >> +        }
> >>      }
> >> +
> >>      err = slotid_cap_init(dev, 0, bridge_dev->chassis_nr, 0);
> >>      if (err) {
> >>          goto slotid_error;
> >>      }
> >> +
> >> +    if (!hotplug_enabled(bridge_dev)) {
> >> +        return 0;
> >> +    }
> >> +
> >>      if ((bridge_dev->flags & (1 << PCI_BRIDGE_DEV_F_MSI_REQ)) &&
> >>          msi_supported) {
> >>          err = msi_init(dev, 0, 1, true, true);
> >> @@ -79,7 +95,9 @@ static int pci_bridge_dev_initfn(PCIDevice *dev)
> >>  msi_error:
> >>      slotid_cap_cleanup(dev);
> >>  slotid_error:
> >> -    shpc_cleanup(dev, &bridge_dev->bar);
> >> +    if (hotplug_enabled(bridge_dev)) {
> >> +        shpc_cleanup(dev, &bridge_dev->bar);
> >> +    }
> >>  shpc_error:
> >>      pci_bridge_exitfn(dev);
> >>  bridge_error:
> >> @@ -89,53 +107,101 @@ bridge_error:
> >>  static void pci_bridge_dev_exitfn(PCIDevice *dev)
> >>  {
> >>      PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(dev);
> >> +
> >>      if (msi_present(dev)) {
> >>          msi_uninit(dev);
> >>      }
> >>      slotid_cap_cleanup(dev);
> >> -    shpc_cleanup(dev, &bridge_dev->bar);
> >> +    if (hotplug_enabled(bridge_dev)) {
> >> +        shpc_cleanup(dev, &bridge_dev->bar);
> >> +    }
> >>      pci_bridge_exitfn(dev);
> >>  }
> >>  
> >>  static void pci_bridge_dev_instance_finalize(Object *obj)
> >>  {
> >> +    /* this function is idempotent and handles (PCIDevice.shpc == NULL) */
> >>      shpc_free(PCI_DEVICE(obj));
> >>  }
> >>  
> >>  static void pci_bridge_dev_write_config(PCIDevice *d,
> >>                                          uint32_t address, uint32_t val, 
> >> int len)
> >>  {
> >> +    PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(d);
> >> +
> >>      pci_bridge_write_config(d, address, val, len);
> >>      if (msi_present(d)) {
> >>          msi_write_config(d, address, val, len);
> >>      }
> >> -    shpc_cap_write_config(d, address, val, len);
> >> +    if (hotplug_enabled(bridge_dev)) {
> >> +        shpc_cap_write_config(d, address, val, len);
> >> +    }
> >>  }
> >>  
> >>  static void qdev_pci_bridge_dev_reset(DeviceState *qdev)
> >>  {
> >>      PCIDevice *dev = PCI_DEVICE(qdev);
> >> +    PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(dev);
> >>  
> >>      pci_bridge_reset(qdev);
> >> -    shpc_reset(dev);
> >> +    if (hotplug_enabled(bridge_dev)) {
> >> +        shpc_reset(dev);
> >> +    }
> >>  }
> >>  
> >>  static Property pci_bridge_dev_properties[] = {
> >>                      /* Note: 0 is not a legal chassis number. */
> >>      DEFINE_PROP_UINT8("chassis_nr", PCIBridgeDev, chassis_nr, 0),
> >>      DEFINE_PROP_BIT("msi", PCIBridgeDev, flags, PCI_BRIDGE_DEV_F_MSI_REQ, 
> >> true),
> >> +    DEFINE_PROP_BIT("hotplug", PCIBridgeDev, flags, 
> >> PCI_BRIDGE_DEV_F_HOTPLUG,
> >> +                    true),
> >>      DEFINE_PROP_END_OF_LIST(),
> >>  };
> >>  
> >> +static bool pci_bridge_dev_shpc_exists(void *opaque, int version_id)
> >> +{
> >> +    PCIDevice *dev = opaque;
> >> +    PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(dev);
> >> +
> >> +    return hotplug_enabled(bridge_dev);
> >> +}
> >> +
> >>  static const VMStateDescription pci_bridge_dev_vmstate = {
> >>      .name = "pci_bridge",
> >>      .fields = (VMStateField[]) {
> >>          VMSTATE_PCI_DEVICE(parent_obj, PCIBridge),
> >> -        SHPC_VMSTATE(shpc, PCIDevice, NULL),
> >> +        SHPC_VMSTATE(shpc, PCIDevice, pci_bridge_dev_shpc_exists),
> >>          VMSTATE_END_OF_LIST()
> >>      }
> >>  };
> >>  
> >> +static void pci_bridge_dev_hotplug_cb(HotplugHandler *hotplug_dev,
> >> +                                      DeviceState *dev, Error **errp)
> >> +{
> >> +    PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(hotplug_dev);
> >> +
> >> +    if (!hotplug_enabled(bridge_dev)) {
> >> +        error_setg(errp, "standard hotplug controller has been disabled 
> >> for "
> >> +                   "this %s", TYPE_PCI_BRIDGE_DEV);
> >> +        return;
> >> +    }
> >> +    shpc_device_hotplug_cb(hotplug_dev, dev, errp);
> >> +}
> >> +
> >> +static void pci_bridge_dev_hot_unplug_request_cb(HotplugHandler 
> >> *hotplug_dev,
> >> +                                                 DeviceState *dev,
> >> +                                                 Error **errp)
> >> +{
> >> +    PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(hotplug_dev);
> >> +
> >> +    if (!hotplug_enabled(bridge_dev)) {
> >> +        error_setg(errp, "standard hotplug controller has been disabled 
> >> for "
> >> +                   "this %s", TYPE_PCI_BRIDGE_DEV);
> >> +        return;
> >> +    }
> >> +    shpc_device_hot_unplug_request_cb(hotplug_dev, dev, errp);
> >> +}
> >> +
> >>  static void pci_bridge_dev_class_init(ObjectClass *klass, void *data)
> >>  {
> >>      DeviceClass *dc = DEVICE_CLASS(klass);
> >> @@ -154,8 +220,8 @@ static void pci_bridge_dev_class_init(ObjectClass 
> >> *klass, void *data)
> >>      dc->props = pci_bridge_dev_properties;
> >>      dc->vmsd = &pci_bridge_dev_vmstate;
> >>      set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
> >> -    hc->plug = shpc_device_hotplug_cb;
> >> -    hc->unplug_request = shpc_device_hot_unplug_request_cb;
> >> +    hc->plug = pci_bridge_dev_hotplug_cb;
> >> +    hc->unplug_request = pci_bridge_dev_hot_unplug_request_cb;
> >>  }
> >>  
> >>  static const TypeInfo pci_bridge_dev_info = {
> >> -- 
> >> 1.8.3.1
> >>