Re: [Qemu-devel] [PATCH v4 2/2] enable multi-function hot-add

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

On Thu, Oct 22, 2015 at 07:57:52PM +0800, Cao jin wrote:
> Enable pcie device multifunction hot, just ensure the function 0
> added last, then driver will got the notification to scan all the
> function in the slot.
> 
> Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
> ---
>  hw/pci/pci.c         | 29 +++++++++++++++++++++++++++++
>  hw/pci/pci_host.c    | 11 +++++++++--
>  hw/pci/pcie.c        | 18 +++++++++---------
>  include/hw/pci/pci.h |  1 +
>  4 files changed, 48 insertions(+), 11 deletions(-)
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index b0bf540..c068248 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -847,6 +847,7 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev, PCIBus *bus,
>      PCIConfigWriteFunc *config_write = pc->config_write;
>      Error *local_err = NULL;
>      AddressSpace *dma_as;
> +    DeviceState *dev = DEVICE(pci_dev);
>  
>      if (devfn < 0) {
>          for(devfn = bus->devfn_min ; devfn < ARRAY_SIZE(bus->devices);
> @@ -864,6 +865,16 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev, PCIBus *bus,
>                     PCI_SLOT(devfn), PCI_FUNC(devfn), name,
>                     bus->devices[devfn]->name);
>          return NULL;
> +    } else if (dev->hotplugged &&
> +               ((!pc->is_express && bus->devices[PCI_DEVFN(PCI_SLOT(devfn), 0)]) ||
> +                (pc->is_express && bus->devices[0]))) {

So let's change pci_is_function_0 to pci_get_function_0 and reuse here?

> +        error_setg(errp, "PCI: slot %d function 0 already ocuppied by %s,"
> +                   " new func %s cannot be exposed to guest.",
> +                   PCI_SLOT(devfn),
> +                   bus->devices[PCI_DEVFN(PCI_SLOT(devfn), 0)]->name,
> +                   name);
> +
> +       return NULL;
>      }
>  
>      pci_dev->bus = bus;
> @@ -2454,6 +2465,24 @@ void pci_bus_get_w64_range(PCIBus *bus, Range *range)
>      pci_for_each_device_under_bus(bus, pci_dev_get_w64, range);
>  }
>  
> +/* ARI device function number range is 0-255, means has only 1 function0;
> + * while PCI device has 1 function0 in each slot(up to 32 slot) */
> +bool pci_is_function_0(PCIDevice *pci_dev)
> +{
> +    PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(pci_dev);
> +    bool is_func0 = false;
> +
> +    if (pc->is_express) {


This is not what the spec says. It says:
devices connected to an upstream port.


> +        if (!pci_dev->devfn)
> +            is_func0 = true;

Just do return !pci_dev->devfn here.

> +    } else {
> +        if(!PCI_FUNC(pci_dev->devfn))
> +            is_func0 = true;
> +    }
> +
> +    return is_func0;
> +}
> +
>  static const TypeInfo pci_device_type_info = {
>      .name = TYPE_PCI_DEVICE,
>      .parent = TYPE_DEVICE,
> diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
> index 3e26f92..40087c9 100644
> --- a/hw/pci/pci_host.c
> +++ b/hw/pci/pci_host.c
> @@ -20,6 +20,7 @@
>  
>  #include "hw/pci/pci.h"
>  #include "hw/pci/pci_host.h"
> +#include "hw/pci/pci_bus.h"
>  #include "trace.h"
>  
>  /* debug PCI */
> @@ -75,7 +76,10 @@ void pci_data_write(PCIBus *s, uint32_t addr, uint32_t val, int len)
>      PCIDevice *pci_dev = pci_dev_find_by_addr(s, addr);
>      uint32_t config_addr = addr & (PCI_CONFIG_SPACE_SIZE - 1);
>  
> -    if (!pci_dev) {
> +    /* non-zero functions are only exposed when function 0 is present,
> +     * allowing direct removal of unexposed functions.
> +     */
> +    if (!pci_dev || !s->devices[PCI_DEVFN(PCI_SLOT(pci_dev->devfn), 0)]) {

Reuse pci_get_function_0 here too?

>          return;
>      }
>  
> @@ -91,7 +95,10 @@ uint32_t pci_data_read(PCIBus *s, uint32_t addr, int len)
>      uint32_t config_addr = addr & (PCI_CONFIG_SPACE_SIZE - 1);
>      uint32_t val;
>  
> -    if (!pci_dev) {
> +    /* non-zero functions are only exposed when function 0 is present,
> +     * allowing direct removal of unexposed functions.
> +     */
> +    if (!pci_dev || !s->devices[PCI_DEVFN(PCI_SLOT(pci_dev->devfn), 0)]) {

And here?

>          return ~0x0;
>      }
>  
> diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> index b1adeaf..d0a8006 100644
> --- a/hw/pci/pcie.c
> +++ b/hw/pci/pcie.c
> @@ -249,16 +249,16 @@ void pcie_cap_slot_hotplug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
>          return;
>      }
>  
> -    /* TODO: multifunction hot-plug.
> -     * Right now, only a device of function = 0 is allowed to be
> -     * hot plugged/unplugged.
> +    /* To enable multifunction hot-plug, we just ensure the function
> +     * 0 added last. Until function 0 added, we set the sltsta and
> +     * inform OS via event notification.

Should be "when function 0 is added".

>       */
> -    assert(PCI_FUNC(pci_dev->devfn) == 0);
> -
> -    pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTSTA,
> -                               PCI_EXP_SLTSTA_PDS);
> -    pcie_cap_slot_event(PCI_DEVICE(hotplug_dev),
> -                        PCI_EXP_HP_EV_PDC | PCI_EXP_HP_EV_ABP);
> +    if (pci_is_function_0(pci_dev)) {
> +        pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTSTA,
> +                                   PCI_EXP_SLTSTA_PDS);
> +        pcie_cap_slot_event(PCI_DEVICE(hotplug_dev),
> +                            PCI_EXP_HP_EV_PDC | PCI_EXP_HP_EV_ABP);
> +    }
>  }
>  
>  static void pcie_unplug_device(PCIBus *bus, PCIDevice *dev, void *opaque)
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index f5e7fd8..2820cfd 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -397,6 +397,7 @@ void pci_for_each_bus_depth_first(PCIBus *bus,
>                                    void *(*begin)(PCIBus *bus, void *parent_state),
>                                    void (*end)(PCIBus *bus, void *state),
>                                    void *parent_state);
> +bool pci_is_function_0(PCIDevice *pci_dev);
>  
>  /* Use this wrapper when specific scan order is not required. */
>  static inline
> -- 
> 2.1.0