From: Peter Maydell <peter.maydell@linaro.org>
To: Jason Wang <jasowang@redhat.com>
Cc: Dmitry Fleytman <dmitry.fleytman@gmail.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Li Qiang <liq3ea@gmail.com>, Li Qiang <liq3ea@163.com>,
QEMU Developers <qemu-devel@nongnu.org>,
Alexander Bulekov <alxndr@bu.edu>,
Gerd Hoffmann <kraxel@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [RFC 0/3] try to solve the DMA to MMIO issue
Date: Thu, 3 Sep 2020 11:53:12 +0100 [thread overview]
Message-ID: <CAFEAcA9mvMaR5MJJ74Vv63TG6frWnMeSZA19Zxv8TUceudPUTQ@mail.gmail.com> (raw)
In-Reply-To: <b840aab8-542d-af43-43e5-0a07f442b5d5@redhat.com>
On Thu, 3 Sep 2020 at 04:55, Jason Wang <jasowang@redhat.com> wrote:
> I think we still need to seek a way to address this issue completely.
>
> How about adding a flag in MemoryRegionOps and detect the reentrancy
> through that flag?
This won't catch everything. Consider this situation:
Device A makes DMA access to device B
Device B's write-handling causes it to raise an
outbound qemu_irq signal
The qemu_irq signal is connected to device A
Now we have reentered into device A's code
That is to say, the problem is general to "device A does
something that affects device B" links of all kinds, which
can form loops. Self-DMA is just an easy way to find one
category of these with the fuzzer.
thanks
-- PMM
next prev parent reply other threads:[~2020-09-03 10:54 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-02 16:22 [RFC 0/3] try to solve the DMA to MMIO issue Li Qiang
2020-09-02 16:22 ` [RFC 1/3] e1000e: make the IO handler reentrant Li Qiang
2020-09-02 16:22 ` [RFC 2/3] xhci: " Li Qiang
2020-09-02 16:22 ` [RFC 3/3] virtio-gpu: " Li Qiang
2020-09-03 5:12 ` Michael Tokarev
2020-09-03 10:32 ` Li Qiang
2020-09-03 3:54 ` [RFC 0/3] try to solve the DMA to MMIO issue Jason Wang
2020-09-03 4:06 ` Alexander Bulekov
2020-09-03 4:24 ` Jason Wang
2020-09-03 4:50 ` Li Qiang
2020-09-03 6:16 ` Jason Wang
2020-09-03 6:28 ` Li Qiang
2020-09-03 10:53 ` Peter Maydell [this message]
2020-09-03 11:11 ` Li Qiang
2020-09-03 11:19 ` Peter Maydell
2020-09-03 11:23 ` Li Qiang
2020-09-03 11:28 ` Peter Maydell
2020-09-03 13:35 ` Philippe Mathieu-Daudé
2020-09-03 13:41 ` Peter Maydell
2020-09-04 2:45 ` Jason Wang
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