Re: [Qemu-devel] [PATCH] hw/pci: completed master-abort emulation

[Michael S. Tsirkin]

On Mon, Sep 23, 2013 at 02:01:17PM +0300, Marcel Apfelbaum wrote:
> This patch is implemented on top of series:
> [PATCH v5 0/3] pci: implement upstream master abort protocol
> 
> Added "master abort io" background region for PCIBus.
> 
> Added "master abort mem" region to catch transactions initiated
> by pci devices targeted to unassigned addresses.
> 
> Enabled "master abort" regions for PCI-2-PCI bridge's secondary bus.
> 
> Set "Received Master Abort" Bit on Status/Secondary Status
> register as defined in the PCI Spec.
> 
> Signed-off-by: Marcel Apfelbaum <address@hidden>

I think it will be easier to review the complete
series, not an incremental patch.

We probably need to think what's the right thing
to do for master abort mode since we do not
emulate SERR. Do we make it writeable at all?

It's a pci only bit:
        When the Master-Abort Mode bit is cleared and a posted write transaction
        forwarded by the
        bridge terminates with a Master-Abort, no error is reported (note that
        the Master-Abort bit
        is still set). When the Master-Abort Mode bit is set and a posted write
        transaction forwarded
        by the bridge terminates with a Master-Abort on the destination bus, the
        bridge must:
        Assert SERR# on the primary interfaceCommand register)
        (if enabled by the SERR# Enable bitin the
        Set the Signaled System Errorbit in the Command register)
        bitin the Status register (if enabled by the SERR# Enable)

one way to do this would be not to set Master-Abort bit even
though spec says we should, and pretend there was no error.

> ---
>  hw/pci/pci.c             | 115 
> ++++++++++++++++++++++++++++++++++++++++++-----
>  hw/pci/pci_bridge.c      |  10 +++++
>  include/hw/pci/pci.h     |   3 ++
>  include/hw/pci/pci_bus.h |   1 +
>  4 files changed, 118 insertions(+), 11 deletions(-)
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index d8a1b11..1f4e707 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -283,17 +283,76 @@ const char *pci_root_bus_path(PCIDevice *dev)
>      return rootbus->qbus.name;
>  }
>  
> +static PCIDevice *pci_bus_find_host(PCIBus *bus)
> +{
> +    PCIDevice *dev;
> +    int i;
> +
> +    for (i = 0; i < ARRAY_SIZE(bus->devices); ++i) {
> +        dev = bus->devices[i];
> +        if (dev) {
> +            PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(dev);
> +            if (pc->class_id == PCI_CLASS_BRIDGE_HOST) {

In fact you can do this easier:
         pci_get_word(dev->config + PCI_CLASS_DEVICE) == PCI_CLASS_BRIDGE_HOST

> +                return dev;
> +            }
> +        }
> +    }
> +
> +    return NULL;
> +}
> +
> +static void master_abort(void *opaque)
> +{
> +    PCIDevice *master_dev = NULL;
> +    PCIDeviceClass *pc;
> +    PCIBus *bus;
> +    int downstream;

bool?

> +
> +    if (object_dynamic_cast(OBJECT(opaque), TYPE_PCI_DEVICE)) {

Please don't do dynamic cast just because you can.
You know very well what kind of object you pass
when you create the MR.
So just call the appropriate function.

> +        master_dev = PCI_DEVICE(opaque);
> +        bus = master_dev->bus;
> +        while (!pci_bus_is_root(bus)) {
> +            master_dev = bus->parent_dev;
> +            bus = master_dev->bus;
> +        }
> +        downstream = 0;
> +    }
> +
> +    if (object_dynamic_cast(OBJECT(opaque), TYPE_PCI_BUS)) {
> +        bus = PCI_BUS(opaque);
> +        if (pci_bus_is_root(bus)) {
> +            master_dev = pci_bus_find_host(bus);
> +        } else { /* bus behind a PCI-2-PCI bridge */
> +            master_dev = bus->parent_dev;
> +        }

So the reason for this is that device to device MA
is still not implemented here, correct?
If it was it would be just one instance of it.
I'm not saying this must block this patch, however
there should be a code comment to this effect,
and commit log should mention this explicitly.

> +        downstream = 1;
> +    }
> +
> +    assert(master_dev);
> +    pc = PCI_DEVICE_GET_CLASS(master_dev);
> +

There's very little common code between devices and
buses. So just use 2 functions.

> +    if (downstream && pc->is_bridge) {
> +        pci_word_test_and_set_mask(master_dev->config + PCI_SEC_STATUS,
> +                                   PCI_STATUS_REC_MASTER_ABORT);
> +    } else {
> +        pci_word_test_and_set_mask(master_dev->config + PCI_STATUS,
> +                                   PCI_STATUS_REC_MASTER_ABORT);
> +    }
> +}
> +
>  static uint64_t master_abort_mem_read(void *opaque, hwaddr addr, unsigned 
> size)
>  {
> -   return -1ULL;

I didn't notice but this means there were 3 spaces here in previous
patch?

> +    master_abort(opaque);
> +    return -1ULL;
>  }
>  
>  static void master_abort_mem_write(void *opaque, hwaddr addr, uint64_t val,
>                                     unsigned size)
>  {
> +    master_abort(opaque);
>  }
>  
> -static const MemoryRegionOps master_abort_mem_ops = {
> +static const MemoryRegionOps master_abort_ops = {
>      .read = master_abort_mem_read,
>      .write = master_abort_mem_write,
>      .endianness = DEVICE_LITTLE_ENDIAN,
> @@ -301,6 +360,23 @@ static const MemoryRegionOps master_abort_mem_ops = {
>  
>  #define MASTER_ABORT_MEM_PRIORITY INT_MIN
>  
> +void pci_bus_master_abort_init(PCIBus *bus, const char *mem, const char *io)
> +{
> +    memory_region_init_io(&bus->master_abort_mem, OBJECT(bus),
> +                          &master_abort_ops, bus, mem,
> +                          memory_region_size(bus->address_space_mem));
> +    memory_region_add_subregion_overlap(bus->address_space_mem,
> +                                        0, &bus->master_abort_mem,
> +                                        MASTER_ABORT_MEM_PRIORITY);
> +
> +    memory_region_init_io(&bus->master_abort_io, OBJECT(bus),
> +                          &master_abort_ops, bus, io,
> +                          memory_region_size(bus->address_space_io));
> +    memory_region_add_subregion_overlap(bus->address_space_io,
> +                                        0, &bus->master_abort_io,
> +                                        MASTER_ABORT_MEM_PRIORITY);
> +}
> +
>  static void pci_bus_init(PCIBus *bus, DeviceState *parent,
>                           const char *name,
>                           MemoryRegion *address_space_mem,
> @@ -312,13 +388,8 @@ static void pci_bus_init(PCIBus *bus, DeviceState 
> *parent,
>      bus->address_space_mem = address_space_mem;
>      bus->address_space_io = address_space_io;
>  
> -
> -    memory_region_init_io(&bus->master_abort_mem, OBJECT(bus),
> -                          &master_abort_mem_ops, bus, "pci-master-abort",
> -                          memory_region_size(bus->address_space_mem));
> -    memory_region_add_subregion_overlap(bus->address_space_mem,
> -                                        0, &bus->master_abort_mem,
> -                                        MASTER_ABORT_MEM_PRIORITY);
> +    pci_bus_master_abort_init(bus, "pci-master-abort-mem",
> +                              "pci-master-abort-io");
>  
>      /* host bridge */
>      QLIST_INIT(&bus->child);
> @@ -840,9 +911,24 @@ static PCIDevice *do_pci_register_device(PCIDevice 
> *pci_dev, PCIBus *bus,
>      pci_dev->bus = bus;
>      dma_as = pci_device_iommu_address_space(pci_dev);
>  
> -    memory_region_init_alias(&pci_dev->bus_master_enable_region,
> -                             OBJECT(pci_dev), "bus master",
> +    memory_region_init(&pci_dev->bus_master_enable_region, NULL,
> +                       "bus master", UINT64_MAX);
> +
> +    memory_region_init_io(&pci_dev->bus_master_abort_mem, OBJECT(bus),
> +                          &master_abort_ops, OBJECT(pci_dev),
> +                          "bus master master-abort",
> +                          
> memory_region_size(&pci_dev->bus_master_enable_region));
> +    memory_region_add_subregion_overlap(&pci_dev->bus_master_enable_region,
> +                                        0, &pci_dev->bus_master_abort_mem,
> +                                        MASTER_ABORT_MEM_PRIORITY);
> +
> +    memory_region_init_alias(&pci_dev->bus_master_dma_mem,
> +                             OBJECT(pci_dev), "bus master dma",
>                               dma_as->root, 0, 
> memory_region_size(dma_as->root));
> +    memory_region_add_subregion_overlap(&pci_dev->bus_master_enable_region,
> +                                        0, &pci_dev->bus_master_dma_mem, 0);
> +
> +
>      memory_region_set_enabled(&pci_dev->bus_master_enable_region, false);
>      address_space_init(&pci_dev->bus_master_as, 
> &pci_dev->bus_master_enable_region,
>                         name);
> @@ -901,6 +987,13 @@ static void do_pci_unregister_device(PCIDevice *pci_dev)
>      pci_config_free(pci_dev);
>  
>      address_space_destroy(&pci_dev->bus_master_as);
> +    memory_region_del_subregion(&pci_dev->bus_master_enable_region,
> +                                &pci_dev->bus_master_dma_mem);
> +    memory_region_del_subregion(&pci_dev->bus_master_enable_region,
> +                                &pci_dev->bus_master_abort_mem);
> +    memory_region_destroy(&pci_dev->bus_master_dma_mem);
> +    memory_region_destroy(&pci_dev->bus_master_abort_mem);
> +
>      memory_region_destroy(&pci_dev->bus_master_enable_region);
>  }
>  
> diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
> index e6b22b8..56b682f 100644
> --- a/hw/pci/pci_bridge.c
> +++ b/hw/pci/pci_bridge.c
> @@ -376,6 +376,10 @@ int pci_bridge_initfn(PCIDevice *dev, const char 
> *typename)
>      sec_bus->address_space_io = &br->address_space_io;
>      memory_region_init(&br->address_space_io, OBJECT(br), "pci_bridge_io", 
> 65536);
>      br->windows = pci_bridge_region_init(br);
> +
> +    pci_bus_master_abort_init(sec_bus, "pci_bridge_master_abort_mem",
> +                              "pci_bridge_master_abort_io");
> +
>      QLIST_INIT(&sec_bus->child);
>      QLIST_INSERT_HEAD(&parent->child, sec_bus, sibling);
>      return 0;
> @@ -389,6 +393,12 @@ void pci_bridge_exitfn(PCIDevice *pci_dev)
>      QLIST_REMOVE(&s->sec_bus, sibling);
>      pci_bridge_region_del(s, s->windows);
>      pci_bridge_region_cleanup(s, s->windows);
> +    memory_region_del_subregion(s->sec_bus.address_space_mem,
> +                                &s->sec_bus.master_abort_mem);
> +    memory_region_del_subregion(s->sec_bus.address_space_io,
> +                                &s->sec_bus.master_abort_io);
> +    memory_region_destroy(&s->sec_bus.master_abort_mem);
> +    memory_region_destroy(&s->sec_bus.master_abort_io);
>      memory_region_destroy(&s->address_space_mem);
>      memory_region_destroy(&s->address_space_io);
>      /* qbus_free() is called automatically by qdev_free() */
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index 37979aa..d69e06d 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -242,6 +242,8 @@ struct PCIDevice {
>      PCIIORegion io_regions[PCI_NUM_REGIONS];
>      AddressSpace bus_master_as;
>      MemoryRegion bus_master_enable_region;
> +    MemoryRegion bus_master_dma_mem;
> +    MemoryRegion bus_master_abort_mem;
>  
>      /* do not access the following fields */
>      PCIConfigReadFunc *config_read;
> @@ -357,6 +359,7 @@ PCIBus *pci_bus_new(DeviceState *parent, const char *name,
>                      MemoryRegion *address_space_mem,
>                      MemoryRegion *address_space_io,
>                      uint8_t devfn_min, const char *typename);
> +void pci_bus_master_abort_init(PCIBus *bus, const char *mem, const char *io);
>  void pci_bus_irqs(PCIBus *bus, pci_set_irq_fn set_irq, pci_map_irq_fn 
> map_irq,
>                    void *irq_opaque, int nirq);
>  int pci_bus_get_irq_level(PCIBus *bus, int irq_num);
> diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
> index 2ad5edb..57b1541 100644
> --- a/include/hw/pci/pci_bus.h
> +++ b/include/hw/pci/pci_bus.h
> @@ -24,6 +24,7 @@ struct PCIBus {
>      MemoryRegion *address_space_mem;
>      MemoryRegion *address_space_io;
>      MemoryRegion master_abort_mem;
> +    MemoryRegion master_abort_io;
>  
>      QLIST_HEAD(, PCIBus) child; /* this will be replaced by qdev later */
>      QLIST_ENTRY(PCIBus) sibling;/* this will be replaced by qdev later */
> -- 
> 1.8.3.1