From: Peter Xu <peterx@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: "David Hildenbrand" <david@redhat.com>,
"Jason Wang" <jasowang@redhat.com>, "Li Qiang" <liq3ea@gmail.com>,
"QEMU Developers" <qemu-devel@nongnu.org>,
"Qiuhao Li" <Qiuhao.Li@outlook.com>,
"Alexander Bulekov" <alxndr@bu.edu>,
qemu-arm <qemu-arm@nongnu.org>,
"Gerd Hoffmann" <kraxel@redhat.com>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Edgar E . Iglesias" <edgar.iglesias@gmail.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>
Subject: Re: [RFC PATCH v2 0/5] physmem: Have flaview API check bus permission from MemTxAttrs argument
Date: Mon, 23 Aug 2021 16:50:37 -0400 [thread overview]
Message-ID: <YSQKHaGiJZE5OAk2@t490s> (raw)
In-Reply-To: <CAFEAcA9_=6n4w86gD3MHhiLeCiui9_+ePT7E2sSHdSRufUJdyA@mail.gmail.com>
On Mon, Aug 23, 2021 at 08:10:50PM +0100, Peter Maydell wrote:
> On Mon, 23 Aug 2021 at 17:42, Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
> >
> > This series aim to kill a recent class of bug, the infamous
> > "DMA reentrancy" issues found by Alexander while fuzzing.
> >
> > Introduce the 'bus_perm' field in MemTxAttrs, defining 3 bits:
> >
> > - MEMTXPERM_UNSPECIFIED (current default, unchanged behavior)
> > - MEMTXPERM_UNRESTRICTED (allow list approach)
> > - MEMTXPERM_RAM_DEVICE (example of deny list approach)
> >
> > If a transaction permission is not allowed (for example access
> > to non-RAM device), we return the specific MEMTX_BUS_ERROR.
> >
> > Permissions are checked in after the flatview is resolved, and
> > before the access is done, in a new function: flatview_access_allowed().
>
> So I'm not going to say 'no' to this, because we have a real
> recursive-device-handling problem and I don't have a better
> idea to hand, but the thing about this is that we end up with
> behaviour which is not what the real hardware does. I'm not
> aware of any DMA device which has this kind of "can only DMA
> to/from RAM, and aborts on access to a device" behaviour...
Sorry for not being familiar with the context - is there more info regarding
the problem to fix? I'm looking at the links mentioned in the old series:
https://lore.kernel.org/qemu-devel/20200903110831.353476-12-philmd@redhat.com/
https://bugs.launchpad.net/qemu/+bug/1886362
https://bugs.launchpad.net/qemu/+bug/1888606
They seem all marked as fixed now.
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2021-08-23 20:52 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-23 16:41 [RFC PATCH v2 0/5] physmem: Have flaview API check bus permission from MemTxAttrs argument Philippe Mathieu-Daudé
2021-08-23 16:41 ` [RFC PATCH v2 1/5] softmmu/physmem: Simplify flatview_write and address_space_access_valid Philippe Mathieu-Daudé
2021-08-23 18:45 ` Peter Xu
2021-08-23 18:59 ` David Hildenbrand
2021-08-24 9:03 ` Alexander Bulekov
2021-08-24 13:04 ` Stefan Hajnoczi
2021-08-23 16:41 ` [RFC PATCH v2 2/5] hw/intc/arm_gicv3: Check for !MEMTX_OK instead of MEMTX_ERROR Philippe Mathieu-Daudé
2021-08-23 18:46 ` Peter Xu
2021-08-23 19:01 ` David Hildenbrand
2021-08-23 19:07 ` Peter Maydell
2021-08-24 13:04 ` Stefan Hajnoczi
2021-08-23 16:41 ` [RFC PATCH v2 3/5] exec/memattrs: Introduce MemTxAttrs::bus_perm field Philippe Mathieu-Daudé
2021-08-23 18:41 ` Peter Xu
2021-08-23 19:04 ` David Hildenbrand
2021-12-15 17:14 ` Philippe Mathieu-Daudé
2021-08-24 13:08 ` Stefan Hajnoczi
2021-12-15 17:11 ` Philippe Mathieu-Daudé
2021-08-23 16:41 ` [RFC PATCH v2 4/5] softmmu/physmem: Introduce flatview_access_allowed() to check bus perms Philippe Mathieu-Daudé
2021-08-23 18:43 ` Peter Xu
2021-08-23 19:03 ` David Hildenbrand
2021-08-24 13:13 ` Stefan Hajnoczi
2021-08-23 16:41 ` [RFC PATCH v2 5/5] softmmu/physmem: Have flaview API check MemTxAttrs::bus_perm field Philippe Mathieu-Daudé
2021-08-23 18:45 ` Peter Xu
2021-08-23 19:10 ` David Hildenbrand
2021-08-24 13:15 ` Stefan Hajnoczi
2021-08-24 13:50 ` Philippe Mathieu-Daudé
2021-08-24 14:21 ` Peter Maydell
2021-11-18 21:04 ` Philippe Mathieu-Daudé
2021-08-23 19:10 ` [RFC PATCH v2 0/5] physmem: Have flaview API check bus permission from MemTxAttrs argument Peter Maydell
2021-08-23 20:50 ` Peter Xu [this message]
2021-08-23 22:26 ` Alexander Bulekov
2021-08-24 7:24 ` Philippe Mathieu-Daudé
2021-08-24 9:49 ` Peter Maydell
2021-08-24 12:01 ` Gerd Hoffmann
2021-08-24 12:12 ` Li Qiang
2021-08-24 19:34 ` Peter Xu
2021-08-24 9:25 ` Edgar E. Iglesias
2021-08-24 13:26 ` Stefan Hajnoczi
2021-08-24 8:58 ` Stefan Hajnoczi
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