Re: [Qemu-devel] [PATCH v14 Resend 10/13] pci: add pci device pre-post reset callbacks for host bus reset

[Alex Williamson <alex.williamson@redhat.com>]

On Thu, 2015-12-17 at 09:41 +0800, Cao jin wrote:
> From: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> 
> Particularly, For vfio devices, Once need to recovery devices
> by bus reset such as AER, we always need to reset the host bus
> to recovery the devices under the bus, so we need to add pci device
> callbacks to specify to do host bus reset.
> 
> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/pci/pci.c         | 18 ++++++++++++++++++
>  hw/pci/pci_bridge.c  |  9 +++++++++
>  hw/vfio/pci.c        | 26 ++++++++++++++++++++++++++
>  hw/vfio/pci.h        |  2 ++
>  include/hw/pci/pci.h |  7 +++++++
>  5 files changed, 62 insertions(+)
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index f6ca6ef..64fa2cc 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -247,6 +247,24 @@ static void pci_do_device_reset(PCIDevice *dev)
>      msix_reset(dev);
>  }
>  
> +void pci_device_pre_reset(PCIBus *bus, PCIDevice *dev, void *unused)
> +{
> +    PCIDeviceClass *dc = PCI_DEVICE_GET_CLASS(dev);
> +
> +    if (dc->pre_reset) {
> +        dc->pre_reset(dev);
> +    }
> +}
> +
> +void pci_device_post_reset(PCIBus *bus, PCIDevice *dev, void
> *unused)
> +{
> +    PCIDeviceClass *dc = PCI_DEVICE_GET_CLASS(dev);
> +
> +    if (dc->post_reset) {
> +        dc->post_reset(dev);
> +    }
> +}
> +
>  /*
>   * This function is called on #RST and FLR.
>   * FLR if PCI_EXP_DEVCTL_BCR_FLR is set
> diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
> index 40c97b1..ddb76ab 100644
> --- a/hw/pci/pci_bridge.c
> +++ b/hw/pci/pci_bridge.c
> @@ -267,8 +267,17 @@ void pci_bridge_write_config(PCIDevice *d,
>  
>      newctl = pci_get_word(d->config + PCI_BRIDGE_CONTROL);
>      if (~oldctl & newctl & PCI_BRIDGE_CTL_BUS_RESET) {
> +        /*
> +         * Notify all vfio-pci devices under the bus
> +         * should do physical bus reset.
> +         */
> +        PCIBus *sec_bus = pci_bridge_get_sec_bus(s);
> +        pci_for_each_device(sec_bus, pci_bus_num(sec_bus),
> +                            pci_device_pre_reset, NULL);
>          /* Trigger hot reset on 0->1 transition. */
>          qbus_reset_all(&s->sec_bus.qbus);
> +        pci_for_each_device(sec_bus, pci_bus_num(sec_bus),
> +                            pci_device_post_reset, NULL);
>      }
>  }
>  
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index e17dc89..df32618 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -39,6 +39,7 @@
>  
>  static void vfio_disable_interrupts(VFIOPCIDevice *vdev);
>  static void vfio_mmap_set_enabled(VFIOPCIDevice *vdev, bool
> enabled);
> +static int vfio_pci_hot_reset(VFIOPCIDevice *vdev, bool single);
>  
>  /*
>   * Disabling BAR mmaping can be slow, but toggling it around INTx
> can
> @@ -1888,6 +1889,8 @@ static int
> vfio_check_host_bus_reset(VFIOPCIDevice *vdev)
>      /* List all affected devices by bus reset */
>      devices = &info->devices[0];
>  
> +    vdev->single_depend_dev = (info->count == 1);
> +
>      /* Verify that we have all the groups required */
>      for (i = 0; i < info->count; i++) {
>          PCIHostDeviceAddress host;
> @@ -2029,10 +2032,26 @@ static int
> vfio_check_bus_reset(NotifierWithReturn *n, void *opaque)
>      return vfio_check_host_bus_reset(vdev);
>  }
>  
> +static void vfio_aer_pre_reset(PCIDevice *pdev)
> +{
> +    VFIOPCIDevice *vdev = DO_UPCAST(VFIOPCIDevice, pdev, pdev);
> +
> +    vdev->aer_reset = true;
> +    vfio_pci_hot_reset(vdev, vdev->single_depend_dev);
> +}

Doesn't this lead to multiple host bus resets per guest bus reset in
many cases?  It looks like we'll do it once per vfio-pci device, even
if those devices are on the same host bus.  That's a 1 second operation
per device.  Can we avoid that?  Maybe some sort of sequence ID could
help a device figure out whether it's already been reset as part of a
dependent device for this particular guest bus reset.  Thanks,

Alex

> +
> +static void vfio_aer_post_reset(PCIDevice *pdev)
> +{
> +    VFIOPCIDevice *vdev = DO_UPCAST(VFIOPCIDevice, pdev, pdev);
> +
> +    vdev->aer_reset = false;
> +}
> +
>  static int vfio_setup_aer(VFIOPCIDevice *vdev, uint8_t cap_ver,
>                            int pos, uint16_t size)
>  {
>      PCIDevice *pdev = &vdev->pdev;
> +    PCIDeviceClass *dc = PCI_DEVICE_GET_CLASS(pdev);
>      PCIDevice *dev_iter;
>      uint8_t type;
>      uint32_t errcap;
> @@ -2079,6 +2098,9 @@ static int vfio_setup_aer(VFIOPCIDevice *vdev,
> uint8_t cap_ver,
>      vdev->hotplug_notifier.notify = vfio_check_bus_reset;
>      pci_bus_add_hotplug_notifier(pdev->bus, &vdev-
> >hotplug_notifier);
>  
> +    dc->pre_reset = vfio_aer_pre_reset;
> +    dc->post_reset = vfio_aer_post_reset;
> +
>      pcie_cap_deverr_init(pdev);
>      return pcie_aer_init(pdev, pos, size);
>  
> @@ -2978,6 +3000,10 @@ static void vfio_pci_reset(DeviceState *dev)
>  
>      trace_vfio_pci_reset(vdev->vbasedev.name);
>  
> +    if (vdev->aer_reset) {
> +        return;
> +    }
> +
>      vfio_pci_pre_reset(vdev);
>  
>      if (vdev->resetfn && !vdev->resetfn(vdev)) {
> diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
> index b385f07..5470b97 100644
> --- a/hw/vfio/pci.h
> +++ b/hw/vfio/pci.h
> @@ -142,6 +142,8 @@ typedef struct VFIOPCIDevice {
>      bool no_kvm_intx;
>      bool no_kvm_msi;
>      bool no_kvm_msix;
> +    bool aer_reset;
> +    bool single_depend_dev;
>  
>      NotifierWithReturn hotplug_notifier;
>  } VFIOPCIDevice;
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index 379b6e1..6b1f2d4 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -105,6 +105,9 @@ typedef void PCIMapIORegionFunc(PCIDevice
> *pci_dev, int region_num,
>                                  pcibus_t addr, pcibus_t size, int
> type);
>  typedef void PCIUnregisterFunc(PCIDevice *pci_dev);
>  
> +typedef void PCIPreResetFunc(PCIDevice *pci_dev);
> +typedef void PCIPostResetFunc(PCIDevice *pci_dev);
> +
>  typedef struct PCIIORegion {
>      pcibus_t addr; /* current PCI mapping address. -1 means not
> mapped */
>  #define PCI_BAR_UNMAPPED (~(pcibus_t)0)
> @@ -193,6 +196,8 @@ typedef struct PCIDeviceClass {
>      PCIUnregisterFunc *exit;
>      PCIConfigReadFunc *config_read;
>      PCIConfigWriteFunc *config_write;
> +    PCIPreResetFunc *pre_reset;
> +    PCIPostResetFunc *post_reset;
>  
>      uint16_t vendor_id;
>      uint16_t device_id;
> @@ -380,6 +385,8 @@ bool pci_intx_route_changed(PCIINTxRoute *old,
> PCIINTxRoute *new);
>  void pci_bus_fire_intx_routing_notifier(PCIBus *bus);
>  void pci_device_set_intx_routing_notifier(PCIDevice *dev,
>                                            PCIINTxRoutingNotifier
> notifier);
> +void pci_device_pre_reset(PCIBus *bus, PCIDevice *d, void *opaque);
> +void pci_device_post_reset(PCIBus *bus, PCIDevice *d, void *opaque);
>  void pci_device_reset(PCIDevice *dev);
>  
>  PCIDevice *pci_nic_init_nofail(NICInfo *nd, PCIBus *rootbus,