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Message-ID: <a54ab50a-f35c-26b9-3907-20c014a1120a@epam.com>
Date: Wed, 27 Oct 2021 14:08:13 +0000
From: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@...m.com>
To: Boris Ostrovsky <boris.ostrovsky@...cle.com>,
"xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: "jgross@...e.com" <jgross@...e.com>,
"julien@....org" <julien@....org>,
"sstabellini@...nel.org" <sstabellini@...nel.org>,
"jbeulich@...e.com" <jbeulich@...e.com>,
Anastasiia Lukianenko <Anastasiia_Lukianenko@...m.com>,
Oleksandr Andrushchenko <Oleksandr_Andrushchenko@...m.com>
Subject: Re: [PATCH v5] xen-pciback: allow compiling on other archs than x86
Hi, Boris!
On 27.10.21 15:59, Boris Ostrovsky wrote:
>
> On 9/28/21 3:35 AM, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>>
>> Xen-pciback driver was designed to be built for x86 only. But it
>> can also be used by other architectures, e.g. Arm.
>>
>> Currently PCI backend implements multiple functionalities at a time,
>> such as:
>> 1. It is used as a database for assignable PCI devices, e.g. xl
>> pci-assignable-{add|remove|list} manipulates that list. So, whenever
>> the toolstack needs to know which PCI devices can be passed through
>> it reads that from the relevant sysfs entries of the pciback.
>> 2. It is used to hold the unbound PCI devices list, e.g. when passing
>> through a PCI device it needs to be unbound from the relevant device
>> driver and bound to pciback (strictly speaking it is not required
>> that the device is bound to pciback, but pciback is again used as a
>> database of the passed through PCI devices, so we can re-bind the
>> devices back to their original drivers when guest domain shuts down)
>> 3. Device reset for the devices being passed through
>> 4. Para-virtualised use-cases support
>>
>> The para-virtualised part of the driver is not always needed as some
>> architectures, e.g. Arm or x86 PVH Dom0, are not using backend-frontend
>> model for PCI device passthrough.
>>
>> For such use-cases make the very first step in splitting the
>> xen-pciback driver into two parts: Xen PCI stub and PCI PV backend
>> drivers.
>>
>> For that add new configuration options CONFIG_XEN_PCI_STUB and
>> CONFIG_XEN_PCIDEV_STUB, so the driver can be limited in its
>> functionality, e.g. no support for para-virtualised scenario.
>> x86 platform will continue using CONFIG_XEN_PCIDEV_BACKEND for the
>> fully featured backend driver.
>>
>> Please note, that CONFIG_XEN_PCIDEV_BACKEND and CONFIG_XEN_PCIDEV_STUB
>> are mutually exclusive.
>>
>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>> Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@...m.com>
>> Reviewed-by: Stefano Stabellini <sstabellini@...nel.org>
>
>
> Oleksandr,
>
>
>
> Can you please rebase this on top of 5.15-rc7? There is a bunch of conflicts due to cae7d81a3730dfe08623f8c1083230c8d0987639.
>
I'll try to do that ASAP (what is the deadline for that?)
>
> Thanks.
>
> -boris
>
Thank you,
Oleksandr
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