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Subject: Re: [PATCH] xen: don't require virtio with grants for non-PV guests
To:     Juergen Gross <jgross@suse.com>
Cc:     xen-devel@lists.xenproject.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        Stefano Stabellini <sstabellini@kernel.org>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
References: <20220615084835.27113-1-jgross@suse.com>
From:   Oleksandr <olekstysh@gmail.com>
Message-ID: <6f5b1562-1270-5e83-bf9f-a9a7afc5a725@gmail.com>
Date:   Wed, 15 Jun 2022 18:47:54 +0300
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On 15.06.22 11:48, Juergen Gross wrote:

Hello Juergen

> Commit fa1f57421e0b ("xen/virtio: Enable restricted memory access using
> Xen grant mappings") introduced a new requirement for using virtio
> devices: the backend now needs to support the VIRTIO_F_ACCESS_PLATFORM
> feature.
>
> This is an undue requirement for non-PV guests, as those can be operated
> with existing backends without any problem, as long as those backends
> are running in dom0.
>
> Per default allow virtio devices without grant support for non-PV
> guests.
>
> The setting can be overridden by using the new "xen_virtio_grant"
> command line parameter.
>
> Add a new config item to always force use of grants for virtio.
>
> Fixes: fa1f57421e0b ("xen/virtio: Enable restricted memory access using Xen grant mappings")
> Signed-off-by: Juergen Gross <jgross@suse.com>

Thank you for the fix.


I have tested it on Arm64 guest (XEN_HVM_DOMAIN), it works.

With the "__init" fix (pointed out by Viresh) applied you can add my:

Tested-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> #Arm64 only


[snip]


-- 
Regards,

Oleksandr Tyshchenko