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Re: [PATCH 09/11] xen/arm: Setup MMIO range trap handlers for hardware domain


  • To: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>
  • From: Rahul Singh <Rahul.Singh@xxxxxxx>
  • Date: Wed, 15 Sep 2021 10:45:59 +0000
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  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "julien@xxxxxxx" <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Oleksandr Tyshchenko <Oleksandr_Tyshchenko@xxxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Artem Mygaiev <Artem_Mygaiev@xxxxxxxx>, "roger.pau@xxxxxxxxxx" <roger.pau@xxxxxxxxxx>, Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, Oleksandr Andrushchenko <andr2000@xxxxxxxxx>
  • Delivery-date: Wed, 15 Sep 2021 10:46:24 +0000
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  • Thread-topic: [PATCH 09/11] xen/arm: Setup MMIO range trap handlers for hardware domain

Hi Oleksandr, Stefano,

> On 15 Sep 2021, at 6:30 am, Oleksandr Andrushchenko 
> <Oleksandr_Andrushchenko@xxxxxxxx> wrote:
> 
> Hi, Rahul!
> 
> On 14.09.21 17:24, Oleksandr Andrushchenko wrote:
>> 
>> }
>>>>   +static int pci_ecam_register_mmio_handler(struct domain *d,
>>>> +                                          struct pci_host_bridge *bridge,
>>>> +                                          const struct mmio_handler_ops 
>>>> *ops)
>>>> +{
>>>> +    struct pci_config_window *cfg = bridge->sysdata;
>>>> +
>>>> +    register_mmio_handler(d, ops, cfg->phys_addr, cfg->size, NULL);
>>>> +    return 0;
>>>> +}
>>> Given that struct pci_config_window is generic (it is not specific to
>>> one bridge), I wonder if we even need the .register_mmio_handler
>>> callback here.
>>> 
>>> In fact,pci_host_bridge->sysdata doesn't even need to be a void*, it
>>> could be a struct pci_config_window*, right?
>> 
>> Rahul, this actually may change your series.
>> 
>> Do you think we can do that?
>> 
> This is the only change requested that left unanswered by now.
> 
> Will it be possible that you change the API accordingly, so I can
> 
> implement as Stefano suggests?

We need pci_host_bridge->sysdata as void* in case we need to implement the new 
non-ecam PCI controller in XEN.
Please have a look once in Linux code[1] how bridge->sysdata will be used. 
struct pci_config_window is used only for 
ecam supported host controller. Different PCI host controller will have 
different PCI interface to access the PCI controller.

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/controller/pcie-rcar-host.c#n309

I think we need bridge->sysdata in future to implement the new PCI controller.

Regards,
Rahul
 
> 
> Thanks,
> 
> Oleksandr




 


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