Re: Indefinite recursion in pci_default_read_config

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

On Tue, Dec 15, 2009 at 12:26:15PM +0100, Hannes Reinecke wrote:
> Michael S. Tsirkin wrote:
> > On Tue, Dec 15, 2009 at 12:59:41PM +0200, Avi Kivity wrote:
> >> On 12/15/2009 12:57 PM, Hannes Reinecke wrote:
> >>> Hi all,
> >>>
> >>> I just triggered a nasty indefinite recursion in pci_default_read_config:
> >>>
> >>> uint32_t pci_default_read_config(PCIDevice *d,
> >>>                                   uint32_t address, int len)
> >>> {
> >>>      uint32_t val = 0;
> >>>      assert(len == 1 || len == 2 || len == 4);
> >>>
> >>>      if (pci_access_cap_config(d, address, len)) {
> >>>          return d->cap.config_read(d, address, len);
> >>>      }
> >>>
> >>>      len = MIN(len, pci_config_size(d) - address);
> >>>      memcpy(&val, d->config + address, len);
> >>>      return le32_to_cpu(val);
> >>> }
> >>>
> >>> And d->cap.config_read is pointing to pci_default_read_config:
> >>>
> >>> (gdb) print *d
> >>> $3 = {qdev = {id = 0xc99b10 "01:10.0", state = DEV_STATE_INITIALIZED,
> >>>      opts = 0xc99ad0, hotplugged = 0, info = 0x837e60, parent_bus = 0xc71710,
> >>>      num_gpio_out = 0, gpio_out = 0x0, num_gpio_in = 0, gpio_in = 0x0,
> >>>      child_bus = {lh_first = 0x0}, num_child_bus = 0, sibling = {
> >>>        le_next = 0xc99c30, le_prev = 0xc71730}},
> >>>    config = 0xca3010 "\206\200\312\020\003",
> >>>    cmask = 0xca3120 "\377\377\377\377", wmask = 0xca3230 "",
> >>>    used = 0xca3340 "", bus = 0xc71710, devfn = 32,
> >>>    name = "pci-assign", '\000'<repeats 53 times>, io_regions = {{
> >>>        addr = 4060102656, size = 16384, filtered_size = 16384, type = 0 '\000',
> >>>        map_func = 0x46a5f0<assigned_dev_iomem_map>}, {addr = 0, size = 0,
> >>>        filtered_size = 0, type = 0 '\000', map_func = 0}, {addr = 0, size = 0,
> >>>        filtered_size = 0, type = 0 '\000', map_func = 0}, {addr = 4060119040,
> >>>        size = 16384, filtered_size = 16384, type = 0 '\000',
> >>>        map_func = 0x46a5f0<assigned_dev_iomem_map>}, {addr = 0, size = 0,
> >>>        filtered_size = 0, type = 0 '\000', map_func = 0}, {addr = 0, size = 0,
> >>>        filtered_size = 0, type = 0 '\000', map_func = 0}, {addr = 0, size = 0,
> >>>        filtered_size = 0, type = 0 '\000', map_func = 0}},
> >>>    config_read = 0x46a050<assigned_dev_pci_read_config>,
> >>>    config_write = 0x469f30<assigned_dev_pci_write_config>, irq = 0xca3450,
> >>>    irq_state = 0 '\000', cap_present = 0, msix_cap = 0 '\000',
> >>>    msix_entries_nr = 0, msix_table_page = 0x0, msix_mmio_index = 0,
> >>>    msix_entry_used = 0x0, msix_bar_size = 0, version_id = 2,
> >>>    msix_page_size = 0, msix_irq_entries = 0x0, cap = {supported = 1,
> >>>      start = 64, length = 16,
> >>>      config_read = 0x416770<pci_default_cap_read_config>,
> >>>      config_write = 0x46b750<assigned_device_pci_cap_write_config>}}
> >>>    
> >> Michael?  This is likely a bad merge on my part.  Can you help?
> >>
> >> -- 
> >> error compiling committee.c: too many arguments to function
> > 
> > 
> > Um, yes. I think the following is the right way to do this.
> > As a side note, we really should work to remove all these
> > hacks and make assignment use capability support
> > in upstream qemu.
> > 
> > --
> > 
> > diff --git a/hw/pci.c b/hw/pci.c
> > index 110a5fc..a74d3d4 100644
> > --- a/hw/pci.c
> > +++ b/hw/pci.c
> > @@ -1016,19 +1016,26 @@ static void pci_update_irq_disabled(PCIDevice *d, int was_irq_disabled)
> >      }
> >  }
> >  
> > +uint32_t pci_read_config(PCIDevice *d,
> > +                         uint32_t address, int len)
> > +{
> > +    uint32_t val = 0;
> > +
> > +    len = MIN(len, pci_config_size(d) - address);
> > +    memcpy(&val, d->config + address, len);
> > +    return le32_to_cpu(val);
> > +}
> > +
> >  uint32_t pci_default_read_config(PCIDevice *d,
> >                                   uint32_t address, int len)
> >  {
> > -    uint32_t val = 0;
> >      assert(len == 1 || len == 2 || len == 4);
> >  
> >      if (pci_access_cap_config(d, address, len)) {
> >          return d->cap.config_read(d, address, len);
> >      }
> >  
> > -    len = MIN(len, pci_config_size(d) - address);
> > -    memcpy(&val, d->config + address, len);
> > -    return le32_to_cpu(val);
> > +    return pci_read_config(d, address, len);
> >  }
> >  
> >  static void pci_write_config(PCIDevice *pci_dev,
> > @@ -1052,7 +1059,7 @@ int pci_access_cap_config(PCIDevice *pci_dev, uint32_t address, int len)
> >  uint32_t pci_default_cap_read_config(PCIDevice *pci_dev,
> >                                       uint32_t address, int len)
> >  {
> > -    return pci_default_read_config(pci_dev, address, len);
> > +    return pci_read_config(pci_dev, address, len);
> >  }
> >  
> >  void pci_default_cap_write_config(PCIDevice *pci_dev,
> 
> Ok, works. Except for a missing prototype in hw/pci.h :-)

Should just be static in fact. Here's a better one:


diff --git a/hw/pci.c b/hw/pci.c
index 110a5fc..a74d3d4 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -1016,19 +1016,26 @@ static void pci_update_irq_disabled(PCIDevice *d, int was_irq_disabled)
     }
 }
 
+static uint32_t pci_read_config(PCIDevice *d,
+                                uint32_t address, int len)
+{
+    uint32_t val = 0;
+
+    len = MIN(len, pci_config_size(d) - address);
+    memcpy(&val, d->config + address, len);
+    return le32_to_cpu(val);
+}
+
 uint32_t pci_default_read_config(PCIDevice *d,
                                  uint32_t address, int len)
 {
-    uint32_t val = 0;
     assert(len == 1 || len == 2 || len == 4);
 
     if (pci_access_cap_config(d, address, len)) {
         return d->cap.config_read(d, address, len);
     }
 
-    len = MIN(len, pci_config_size(d) - address);
-    memcpy(&val, d->config + address, len);
-    return le32_to_cpu(val);
+    return pci_read_config(d, address, len);
 }
 
 static void pci_write_config(PCIDevice *pci_dev,
@@ -1052,7 +1059,7 @@ int pci_access_cap_config(PCIDevice *pci_dev, uint32_t address, int len)
 uint32_t pci_default_cap_read_config(PCIDevice *pci_dev,
                                      uint32_t address, int len)
 {
-    return pci_default_read_config(pci_dev, address, len);
+    return pci_read_config(pci_dev, address, len);
 }
 
 void pci_default_cap_write_config(PCIDevice *pci_dev,