Re: [Qemu-devel] [PATCH v3 2/6] pci: introduce pci_host_config_enabled()

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

On Thu, Dec 11, 2014 at 10:20:24AM +0800, Hu Tao wrote:
> This makes code more readable.
> 
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> Reviewed-by: Marcel Apfelbaum <marcel.a@redhat.com>
> ---
>  hw/mips/gt64xxx_pci.c     | 4 ++--
>  hw/pci/pci_host.c         | 5 +++--
>  include/hw/pci/pci_host.h | 5 +++++
>  3 files changed, 10 insertions(+), 4 deletions(-)

We have a ton of other places hard-coding 1<<31,
why special-case these?

> diff --git a/hw/mips/gt64xxx_pci.c b/hw/mips/gt64xxx_pci.c
> index 1f2fe5f..f118c9c 100644
> --- a/hw/mips/gt64xxx_pci.c
> +++ b/hw/mips/gt64xxx_pci.c
> @@ -564,7 +564,7 @@ static void gt64120_writel (void *opaque, hwaddr addr,
>          if (!(s->regs[GT_PCI0_CMD] & 1) && (phb->config_reg & 0x00fff800)) {
>              val = bswap32(val);
>          }
> -        if (phb->config_reg & (1u << 31)) {
> +        if (pci_host_config_enabled(phb)) {
>              pci_data_write(phb->bus, phb->config_reg, val, 4);
>          }
>          break;
> @@ -804,7 +804,7 @@ static uint64_t gt64120_readl (void *opaque,
>          val = phb->config_reg;
>          break;
>      case GT_PCI0_CFGDATA:
> -        if (!(phb->config_reg & (1 << 31))) {
> +        if (!pci_host_config_enabled(phb)) {
>              val = 0xffffffff;
>          } else {
>              val = pci_data_read(phb->bus, phb->config_reg, 4);
> diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
> index 3e26f92..9bc47d8 100644
> --- a/hw/pci/pci_host.c
> +++ b/hw/pci/pci_host.c
> @@ -133,8 +133,9 @@ static void pci_host_data_write(void *opaque, hwaddr addr,
>      PCIHostState *s = opaque;
>      PCI_DPRINTF("write addr " TARGET_FMT_plx " len %d val %x\n",
>                  addr, len, (unsigned)val);
> -    if (s->config_reg & (1u << 31))
> +    if (pci_host_config_enabled(s)) {
>          pci_data_write(s->bus, s->config_reg | (addr & 3), val, len);
> +    }
>  }
>  
>  static uint64_t pci_host_data_read(void *opaque,
> @@ -142,7 +143,7 @@ static uint64_t pci_host_data_read(void *opaque,
>  {
>      PCIHostState *s = opaque;
>      uint32_t val;
> -    if (!(s->config_reg & (1U << 31))) {
> +    if (!pci_host_config_enabled(s)) {
>          return 0xffffffff;
>      }
>      val = pci_data_read(s->bus, s->config_reg | (addr & 3), len);
> diff --git a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h
> index ba31595..b48791d 100644
> --- a/include/hw/pci/pci_host.h
> +++ b/include/hw/pci/pci_host.h
> @@ -65,6 +65,11 @@ uint32_t pci_host_config_read_common(PCIDevice *pci_dev, uint32_t addr,
>  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);
>  
> +static inline bool pci_host_config_enabled(struct PCIHostState *pci_host)
> +{
> +    return pci_host->config_reg & (1U << 31);
> +}
> +

Better:

#define PCI_HOST_CONFIG_ENABLE (1U << 31)

then everyone can just do s->config_reg & PCI_HOST_CONFIG_ENABLE

better as it'll work for code like this:
	phb->config_reg = (pciaddr) | (1u << 31);


>  extern const MemoryRegionOps pci_host_conf_le_ops;
>  extern const MemoryRegionOps pci_host_conf_be_ops;
>  extern const MemoryRegionOps pci_host_data_le_ops;
> -- 
> 1.9.3