From mboxrd@z Thu Jan  1 00:00:00 1970
From: Harini Katakam <harinik@xilinx.com>
Subject: Re: [PATCH 1/3] net: macb: fix random memory corruption on RX with
 64-bit DMA
Date: Mon, 3 Dec 2018 10:14:04 +0530
Message-ID: <CAFcVEC++HykST7bGLf=FhZdcVki=gGpGOe6wrHJ93Mw4QyiLjw@mail.gmail.com>
References: <20181130182137.27974-1-anssi.hannula@bitwise.fi> <20181130182137.27974-2-anssi.hannula@bitwise.fi>
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Cc: Nicolas Ferre <nicolas.ferre@microchip.com>,
        David Miller <davem@davemloft.net>, netdev@vger.kernel.org,
        Harini Katakam <harini.katakam@xilinx.com>,
        Michal Simek <michal.simek@xilinx.com>
To: anssi.hannula@bitwise.fi
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On Fri, Nov 30, 2018 at 11:53 PM Anssi Hannula <anssi.hannula@bitwise.fi> wrote:
>
> 64-bit DMA addresses are split in upper and lower halves that are
> written in separate fields on GEM. For RX, bit 0 of the address is used
> as the ownership bit (RX_USED). When the RX_USED bit is unset the
> controller is allowed to write data to the buffer.
>
> The driver does not guarantee that the controller already sees the upper
> half when the RX_USED bit is cleared, possibly resulting in the
> controller writing an incoming frame to an address with an incorrect
> upper half and therefore possibly corrupting unrelated system memory.
>
> Fix that by adding the necessary DMA memory barrier between the writes.
>
> This corruption was observed on a ZynqMP based system.
>
> Signed-off-by: Anssi Hannula <anssi.hannula@bitwise.fi>
> Fixes: fff8019a08b6 ("net: macb: Add 64 bit addressing support for GEM")
> Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
> Cc: Harini Katakam <harini.katakam@xilinx.com>
> Cc: Michal Simek <michal.simek@xilinx.com>

Acked-by: Harini Katakam <harini.katakam@xilinx.com>

Regards,
Harini