Re: [Xen-devel] [PATCH v2] xen-pciback: optionally allow interrupt enable flag writes

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 12/18/19 10:49 PM, Marek Marczykowski-Górecki wrote:
> ---
>   drivers/xen/xen-pciback/conf_space.c          | 35 ++++++++
>   drivers/xen/xen-pciback/conf_space.h          | 10 +++
>   .../xen/xen-pciback/conf_space_capability.c   | 88 +++++++++++++++++++
>   drivers/xen/xen-pciback/conf_space_header.c   | 19 ++++
>   drivers/xen/xen-pciback/pci_stub.c            | 66 ++++++++++++++
>   drivers/xen/xen-pciback/pciback.h             |  1 +
>   6 files changed, 219 insertions(+)
This also needs an update to Documentation/ABI/testing/sysfs-driver-pciback.


> @@ -64,6 +64,7 @@ static int command_write(struct pci_dev *dev, int offset, u16 
> value, void *data)
>         int err;
>         u16 val;
>         struct pci_cmd_info *cmd = data;
> +       u16 cap_value;
What is this for?


>   
>   	dev_data = pci_get_drvdata(dev);
>         if (!pci_is_enabled(dev) && is_enable_cmd(value)) {
> @@ -117,6 +118,24 @@ static int command_write(struct pci_dev *dev, int offset, 
> u16 value, void *data)
>                 pci_clear_mwi(dev);
>         }
>   
> +	if (dev_data && dev_data->allow_interrupt_control) {
> +               if (!(cmd->val & PCI_COMMAND_INTX_DISABLE) &&
> +                   (value & PCI_COMMAND_INTX_DISABLE)) {
> +                       pci_intx(dev, 0);
> +               } else if ((cmd->val & PCI_COMMAND_INTX_DISABLE) &&
> +                   !(value & PCI_COMMAND_INTX_DISABLE)) {
> +                       /* Do not allow enabling INTx together with MSI or 
> MSI-X. */
> +                       switch (xen_pcibk_get_interrupt_type(dev)) {
> +                               case INTERRUPT_TYPE_NONE:
> +                               case INTERRUPT_TYPE_INTX:
> +                                       pci_intx(dev, 1);
> +                                       break;
> +                               default:
> +                                       return PCIBIOS_SET_FAILED;
> +                       }
> +               }

Perhaps this is slightly easier to read:

if (cmd->val ^ val)  &  PCI_COMMAND_INTX_DISABLE) {
        if (value & PCI_COMMAND_INTX_DISABLE) {
                pci_intx(dev, 0);
        } else {
                /* Do not allow enabling INTx together with MSI or 
MSI-X. */
            switch (xen_pcibk_get_interrupt_type(dev)) {
                case INTERRUPT_TYPE_NONE:
                case INTERRUPT_TYPE_INTX:
                    pci_intx(dev, 1);
                    break;
                default:
                    return PCIBIOS_SET_FAILED;
            }
       }
}

And also, if INTERRUPT_TYPE_INTX, aren't you already enabled?


-boris


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