Re: [Qemu-devel] [PATCH v5 3/3] hw/pci: partially handle pci master abort

[Marcel Apfelbaum <marcel.a@redhat.com>]

On Mon, 2013-09-16 at 12:51 +0300, Michael S. Tsirkin wrote:
> On Mon, Sep 16, 2013 at 12:11:32PM +0300, Marcel Apfelbaum wrote:
> > On Mon, 2013-09-16 at 12:04 +0300, Michael S. Tsirkin wrote:
> > > On Mon, Sep 16, 2013 at 11:21:16AM +0300, Marcel Apfelbaum wrote:
> > > > A MemoryRegion with negative priority was created and
> > > > it spans over all the pci address space.
> > > > It "intercepts" the accesses to unassigned pci
> > > > address space and will follow the pci spec:
> > > >  1. returns -1 on read
> > > >  2. does nothing on write
> > > > 
> > > > Note: setting the RECEIVED MASTER ABORT bit in the STATUS register
> > > >       of the device that initiated the transaction will be
> > > >       implemented in another series
> > > > 
> > > > Signed-off-by: Marcel Apfelbaum <marcel.a@redhat.com>
> 
> So let's hold on to this patch and see how the full
> implementation interacts with it.
> Let's apply 1-2 - I'll put it on my tree unless someone objects.
> 
> > > > ---
> > > > Changes from v4:
> > > >  - Addressed Michael S. Tsirkin comments
> > > >    - Changed PCI master_abort_mem ops endian-nes to DEVICE_LITTLE_ENDIAN
> > > >  - Fixed: overlap master_abort_mem at offset 0, not at
> > > >           bus->address_space_mem.addr
> > > > 
> > > >  hw/pci/pci.c             | 26 ++++++++++++++++++++++++++
> > > >  include/hw/pci/pci_bus.h |  1 +
> > > >  2 files changed, 27 insertions(+)
> > > > 
> > > > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > > > index ad1c1ca..d8a1b11 100644
> > > > --- a/hw/pci/pci.c
> > > > +++ b/hw/pci/pci.c
> > > > @@ -283,6 +283,24 @@ const char *pci_root_bus_path(PCIDevice *dev)
> > > >      return rootbus->qbus.name;
> > > >  }
> > > >  
> > > > +static uint64_t master_abort_mem_read(void *opaque, hwaddr addr, unsigned size)
> > > > +{
> > > > +   return -1ULL;
> > > > +}
> > > > +
> > > > +static void master_abort_mem_write(void *opaque, hwaddr addr, uint64_t val,
> > > > +                                   unsigned size)
> > > > +{
> > > > +}
> > > > +
> > > > +static const MemoryRegionOps master_abort_mem_ops = {
> > > > +    .read = master_abort_mem_read,
> > > > +    .write = master_abort_mem_write,
> > > > +    .endianness = DEVICE_LITTLE_ENDIAN,
> > > > +};
> > > > +
> > > > +#define MASTER_ABORT_MEM_PRIORITY INT_MIN
> > > > +
> > > >  static void pci_bus_init(PCIBus *bus, DeviceState *parent,
> > > >                           const char *name,
> > > >                           MemoryRegion *address_space_mem,
> > > > @@ -294,6 +312,14 @@ 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);
> > > > +
> > > >      /* host bridge */
> > > >      QLIST_INIT(&bus->child);
> > > >  
> > > 
> > > Does this handle devices behind bridges?
> > Yes, tested also for devices behind bridge.
> 
> BTW why does this only handle memory?
> IO should be exactly identical, shouldn't it?
IO is handled on a higher level by Jan Kiszka patch:
    [Qemu-devel] [PATCH v3 1/2] memory: Provide separate handling of unassigned io ports accesses

Thanks,
Marcel

> 
> > > 
> > > 
> > > > diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
> > > > index 9df1788..2ad5edb 100644
> > > > --- a/include/hw/pci/pci_bus.h
> > > > +++ b/include/hw/pci/pci_bus.h
> > > > @@ -23,6 +23,7 @@ struct PCIBus {
> > > >      PCIDevice *parent_dev;
> > > >      MemoryRegion *address_space_mem;
> > > >      MemoryRegion *address_space_io;
> > > > +    MemoryRegion master_abort_mem;
> > > >  
> > > 
> > > Looks like this field is left uninitialized for bridge
> > > devices (they don't seem to call pci_bus_init)?
> > The bridges have no influence with respect to master_abort_mem
> > as it handles *all* unassigned addresses for PCI address space.
> > As stated above, it was tested.
> > 
> > Thanks,
> > Marcel
> >  
> > 
> > > 
> > > >      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
> > 
> >