Re: [PATCH 1/8] pci: pci_default_cap_write_config ignores wmask

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

On Thu, Nov 11, 2010 at 07:55:01PM -0700, Alex Williamson wrote:
> Make use of wmask, just like the rest of config space.
> 
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
> 
>  hw/pci.c |   19 ++++++++-----------
>  1 files changed, 8 insertions(+), 11 deletions(-)
> 
> diff --git a/hw/pci.c b/hw/pci.c
> index 92aaa85..12c47ac 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -1175,13 +1175,14 @@ uint32_t pci_default_read_config(PCIDevice *d,
>      return pci_read_config(d, address, len);
>  }
>  
> -static void pci_write_config(PCIDevice *pci_dev,
> -                             uint32_t address, uint32_t val, int len)
> +static void pci_write_config(PCIDevice *d, uint32_t addr, uint32_t val, int l)
>  {
>      int i;
> -    for (i = 0; i < len; i++) {
> -        pci_dev->config[address + i] = val & 0xff;
> -        val >>= 8;
> +    uint32_t config_size = pci_config_size(d);
> +
> +    for (i = 0; i < l && addr + i < config_size; val >>= 8, ++i) {
> +        uint8_t wmask = d->wmask[addr + i];
> +        d->config[addr + i] = (d->config[addr + i] & ~wmask) | (val & wmask);
>      }
>  }
>


Let's not name an internal static helper pci_write_config.
This is really update_config_by_mask or something like that.
But see below: maybe we don't need it at all?

> @@ -1207,18 +1208,14 @@ void pci_default_cap_write_config(PCIDevice *pci_dev,
>  
>  void pci_default_write_config(PCIDevice *d, uint32_t addr, uint32_t val, int l)
>  {
> -    int i, was_irq_disabled = pci_irq_disabled(d);
> -    uint32_t config_size = pci_config_size(d);
> +    int was_irq_disabled = pci_irq_disabled(d);
>  
>      if (pci_access_cap_config(d, addr, l)) {
>          d->cap.config_write(d, addr, val, l);
>          return;
>      }
>  

I would like to also examine the need for _cap_
functions. Why can assigned devices just do

	pci_default_write_config 
	if (range_overlap(...msi)) {
	}
	if (range_overlap(...msix)) {
	}
and then we could remove all the _cap_ extensions
altogether?

> -    for (i = 0; i < l && addr + i < config_size; val >>= 8, ++i) {
> -        uint8_t wmask = d->wmask[addr + i];
> -        d->config[addr + i] = (d->config[addr + i] & ~wmask) | (val & wmask);
> -    }
> +    pci_write_config(d, addr, val, l);
>  
>  #ifdef CONFIG_KVM_DEVICE_ASSIGNMENT
>      if (kvm_enabled() && kvm_irqchip_in_kernel() &&