Re: [PATCH 1/2] CXL/cxl_type3: add first_dvsec_offset() helper

[Jonathan Cameron via <qemu-devel@nongnu.org>]

On Tue,  2 Apr 2024 09:46:46 +0800
Li Zhijian <lizhijian@fujitsu.com> wrote:

> It helps to figure out where the first dvsec register is located. In
> addition, replace offset and size hardcore with existing macros.
> 
> Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>

I agree we should be using the macros.

The offset calc is a bit specific to the the chosen memory layout,
so not sure it makes sense to break it out to a separate function.

I'll suggest alternative possible approaches in review of next patch.

Jonathan

> ---
>  hw/mem/cxl_type3.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c
> index b0a7e9f11b64..ad2fe7d463fb 100644
> --- a/hw/mem/cxl_type3.c
> +++ b/hw/mem/cxl_type3.c
> @@ -643,6 +643,16 @@ static DOEProtocol doe_cdat_prot[] = {
>      { }
>  };
>  
> +static uint16_t first_dvsec_offset(CXLType3Dev *ct3d)
> +{
> +    uint16_t offset = PCI_CONFIG_SPACE_SIZE;
> +
> +    if (ct3d->sn != UI64_NULL)
> +        offset += PCI_EXT_CAP_DSN_SIZEOF;
> +
> +    return offset;
> +}
> +
>  static void ct3_realize(PCIDevice *pci_dev, Error **errp)
>  {
>      ERRP_GUARD();
> @@ -663,13 +673,10 @@ static void ct3_realize(PCIDevice *pci_dev, Error **errp)
>      pci_config_set_prog_interface(pci_conf, 0x10);
>  
>      pcie_endpoint_cap_init(pci_dev, 0x80);
> -    if (ct3d->sn != UI64_NULL) {
> -        pcie_dev_ser_num_init(pci_dev, 0x100, ct3d->sn);
> -        cxl_cstate->dvsec_offset = 0x100 + 0x0c;
> -    } else {
> -        cxl_cstate->dvsec_offset = 0x100;
> -    }
> +    if (ct3d->sn != UI64_NULL)
> +        pcie_dev_ser_num_init(pci_dev, PCI_CONFIG_SPACE_SIZE, ct3d->sn);
>  
> +    cxl_cstate->dvsec_offset = first_dvsec_offset(ct3d);
>      ct3d->cxl_cstate.pdev = pci_dev;
>      build_dvsecs(ct3d);
>