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Re: [PATCH v5 01/11] xen/arm: xc_domain_ioport_permission(..) not supported on ARM.

  • To: Jan Beulich <jbeulich@xxxxxxxx>
  • From: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>
  • Date: Tue, 12 Oct 2021 10:41:23 +0000
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  • Cc: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>, Rahul Singh <Rahul.Singh@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Andre Przywara <Andre.Przywara@xxxxxxx>, Ian Jackson <iwj@xxxxxxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
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  • Thread-topic: [PATCH v5 01/11] xen/arm: xc_domain_ioport_permission(..) not supported on ARM.

Hi Jan,

> On 12 Oct 2021, at 11:20, Jan Beulich <jbeulich@xxxxxxxx> wrote:
> On 12.10.2021 12:06, Oleksandr Andrushchenko wrote:
>> On 12.10.21 13:01, Jan Beulich wrote:
>>> On 12.10.2021 11:38, Oleksandr Andrushchenko wrote:
>>>> On 12.10.21 12:32, Jan Beulich wrote:
>>>>> The minimal thing I'd suggest (or maybe you're doing this already)
>>>>> would be to expose such BARs to the guest as r/o zero, rather than
>>>>> letting their port nature "shine through".
>>>> If we have the same, but baremetal then which entity disallows
>>>> those BARs to shine?
>>> I'm sorry, but I don't understand what you're trying to say.
>>>> I mean that if guest wants to crash... why
>>>> should we stop it and try emulating something special for it?
>>> This isn't about a guest "wanting to crash", but a driver potentially
>>> getting mislead into thinking that it can driver a device a certain
>>> way.
>> Well, for the guest, as we do not advertise IO in the emulated host
>> bridge, the driver won't be able to allocate any IO at all. Thus, even
>> if we have a BAR with PCI_BASE_ADDRESS_SPACE_IO bit set, the
>> driver won't get anything. So, I think this is equivalent to a baremetal
>> use-case where we have no IO supported by the host bridge and
>> a device with IO BAR.
> Oh, now I follow. Fair enough.

So there is no comment remaining on this patch ?

Would it possible to get an ack on it ?


> Jan



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