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From:   Stefan Chulski <stefanc@marvell.com>
To:     Russell King - ARM Linux admin <linux@armlinux.org.uk>
CC:     Andrew Lunn <andrew@lunn.ch>, "kuba@kernel.org" <kuba@kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "thomas.petazzoni@bootlin.com" <thomas.petazzoni@bootlin.com>,
        "davem@davemloft.net" <davem@davemloft.net>,
        Nadav Haklai <nadavh@marvell.com>,
        Yan Markman <ymarkman@marvell.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "mw@semihalf.com" <mw@semihalf.com>,
        "atenart@kernel.org" <atenart@kernel.org>,
        "rabeeh@solid-run.com" <rabeeh@solid-run.com>
Subject: RE: [EXT] Re: [V2 net-next] net: mvpp2: Add reserved port private
 flag configuration
Thread-Topic: [EXT] Re: [V2 net-next] net: mvpp2: Add reserved port private
 flag configuration
Thread-Index: AQHXFpW4dTR4hPIdakagD6uzfQ/d0ap/ArIAgAfBQuCAAASKgIAAE1Kw
Date:   Tue, 16 Mar 2021 16:51:28 +0000
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> I really, really hope that someone has thought this through:
>=20
>   Packet Processor I/O Interface=A0(PPIO)
>=20
>    The MUSDK PPIO driver provides low-level network interface API for
>    User-Space network drivers/applications. The PPIO infrastrcuture maps
>    Marvell's Packet Processor (PPv2) configuration space and I/O descript=
ors
>    space directly to user-space memory. This allows user-space
>    driver/application to directly process the packet processor I/O rings =
from
>    user space, without any overhead of a copy operation.
>=20
> I realy, really hope that you are not exposing the I/O descriptors to
> userspace, allowing userspace to manipulate the physical addresses in tho=
se
> descriptors, and that userspace is not dealing with physical addresses.
>=20
> If userspace has access to the I/O descriptors with physical addresses, o=
r
> userspace is dealing with physical addresses, then you can say good bye t=
o
> any kind of security on the platform. Essentially, in such a scenario, th=
e entire
> system memory becomes accessible to userspace, which includes the kernel.

Hi Russel,

This patch doesn't relate to MUSDK Packet Processor I/O Interface functiona=
lity.
MUSDK is just another possible use case I could think of for the port reser=
vation feature.
I am not responsible for the MUSDK code, but as far as I know it is based o=
n the generic UIO Kernel interface (uio_pdrv_genirq) so the user can decide=
 whether he wants to enable it or not for his platform.
For the main CM3 management port use case, security is not an issue since t=
he CM3 processor is secured by hardware in the device and its code is authe=
nticated.

Stefan.