Re: [Qemu-devel] [PATCH v3 4/6] pci: remove the limit parameter of pci_host_config_read_common

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

On Thu, Dec 11, 2014 at 10:20:26AM +0800, Hu Tao wrote:
> Since the limit parameter is always set to the size of pci device's
> configuration space,

That's not true in case of pci_data_read, is it?

While the patch might be correct, a better analysis
why that's so seems called for.

> and we can determine the size from the type of pci
> device.
> 
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> ---
>  hw/pci/pci_host.c         | 15 +++++++++++----
>  hw/pci/pcie_host.c        |  9 +--------
>  hw/ppc/spapr_pci.c        |  3 +--
>  include/hw/pci/pci_host.h |  2 +-
>  4 files changed, 14 insertions(+), 15 deletions(-)
> 
> diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
> index 9bc47d8..2b11551 100644
> --- a/hw/pci/pci_host.c
> +++ b/hw/pci/pci_host.c
> @@ -58,12 +58,20 @@ void pci_host_config_write_common(PCIDevice *pci_dev, uint32_t addr,
>  }
>  
>  uint32_t pci_host_config_read_common(PCIDevice *pci_dev, uint32_t addr,
> -                                     uint32_t limit, uint32_t len)
> +                                     uint32_t len)
>  {
> +    uint32_t limit = pci_config_size(pci_dev);
>      uint32_t ret;
>  
>      assert(len <= 4);
> -    ret = pci_dev->config_read(pci_dev, addr, MIN(len, limit - addr));
> +
> +    if (limit <= addr) {
> +        /* conventional pci device can be behind pcie-to-pci bridge.
> +           256 <= addr < 4K has no effects. */
> +        ret = ~0x0;
> +    } else {
> +        ret = pci_dev->config_read(pci_dev, addr, MIN(len, limit - addr));
> +    }
>      trace_pci_cfg_read(pci_dev->name, PCI_SLOT(pci_dev->devfn),
>                         PCI_FUNC(pci_dev->devfn), addr, ret);
>  
> @@ -95,8 +103,7 @@ uint32_t pci_data_read(PCIBus *s, uint32_t addr, int len)
>          return ~0x0;
>      }
>  
> -    val = pci_host_config_read_common(pci_dev, config_addr,
> -                                      PCI_CONFIG_SPACE_SIZE, len);
> +    val = pci_host_config_read_common(pci_dev, config_addr, len);
>      PCI_DPRINTF("%s: %s: addr=%02"PRIx32" val=%08"PRIx32" len=%d\n",
>                  __func__, pci_dev->name, config_addr, val, len);
>  
> diff --git a/hw/pci/pcie_host.c b/hw/pci/pcie_host.c
> index 3db038f..cf8587b 100644
> --- a/hw/pci/pcie_host.c
> +++ b/hw/pci/pcie_host.c
> @@ -62,19 +62,12 @@ static uint64_t pcie_mmcfg_data_read(void *opaque,
>      PCIBus *s = e->pci.bus;
>      PCIDevice *pci_dev = pcie_dev_find_by_mmcfg_addr(s, mmcfg_addr);
>      uint32_t addr;
> -    uint32_t limit;
>  
>      if (!pci_dev) {
>          return ~0x0;
>      }
>      addr = PCIE_MMCFG_CONFOFFSET(mmcfg_addr);
> -    limit = pci_config_size(pci_dev);
> -    if (limit <= addr) {
> -        /* conventional pci device can be behind pcie-to-pci bridge.
> -           256 <= addr < 4K has no effects. */
> -        return ~0x0;
> -    }
> -    return pci_host_config_read_common(pci_dev, addr, limit, len);
> +    return pci_host_config_read_common(pci_dev, addr, len);
>  }
>  
>  static const MemoryRegionOps pcie_mmcfg_ops = {
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index 21b95b3..59c6608 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -105,8 +105,7 @@ static void finish_read_pci_config(sPAPREnvironment *spapr, uint64_t buid,
>          return;
>      }
>  
> -    val = pci_host_config_read_common(pci_dev, addr,
> -                                      pci_config_size(pci_dev), size);
> +    val = pci_host_config_read_common(pci_dev, addr, size);
>  
>      rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>      rtas_st(rets, 1, val);
> diff --git a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h
> index 2bae45a..72a1b8b 100644
> --- a/include/hw/pci/pci_host.h
> +++ b/include/hw/pci/pci_host.h
> @@ -65,7 +65,7 @@ typedef struct PCIHostBridgeClass {
>  void pci_host_config_write_common(PCIDevice *pci_dev, uint32_t addr,
>                                    uint32_t limit, uint32_t val, uint32_t len);
>  uint32_t pci_host_config_read_common(PCIDevice *pci_dev, uint32_t addr,
> -                                     uint32_t limit, uint32_t len);
> +                                     uint32_t len);
>  
>  void pci_data_write(PCIBus *s, uint32_t addr, uint32_t val, int len);
>  uint32_t pci_data_read(PCIBus *s, uint32_t addr, int len);
> -- 
> 1.9.3