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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Wed, 28 Jul 2021 11:01:17 +0200
Message-ID: <CAK8P3a2Hde16rbUPAwvtY7t+uE7C4jM8_pQCqTLj=-d4=T2MSg@mail.gmail.com>
Subject: Re: [PATCH] virtio-console: avoid DMA from vmalloc area
To:     Xianting Tian <xianting.tian@linux.alibaba.com>
Cc:     Arnd Bergmann <arnd@arndb.de>, Amit Shah <amit@kernel.org>,
        gregkh <gregkh@linuxfoundation.org>,
        Omar Sandoval <osandov@fb.com>,
        "open list:DRM DRIVER FOR QEMU'S CIRRUS DEVICE" 
        <virtualization@lists.linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
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On Wed, Jul 28, 2021 at 10:28 AM Xianting Tian
<xianting.tian@linux.alibaba.com> wrote:
> 在 2021/7/28 下午3:25, Arnd Bergmann 写道:
>
> I checked several hvc backends, like drivers/tty/hvc/hvc_riscv_sbi.c,
> drivers/tty/hvc/hvc_iucv.c, drivers/tty/hvc/hvc_rtas.c, they don't use dma.
>
> I not finished all hvc backends check yet. But I think even if all hvc
> backends don't use dma currently, it is still possible that the hvc
> backend using dma will be added in the furture.
>
> So I agree with you it should better be fixed in the hvc framework,
> solve the issue in the first place.

Ok, sounds good to me, no need to check more backends then.
I see the hvc-console driver is listed as 'Odd Fixes' in the maintainer
list, with nobody assigned other than the ppc kernel list (added to Cc).

Once you come up with a fix in hvc_console.c, please send that to the
tty maintainers, the ppc list and me, and I'll review it.

        Arnd