From: Jan Kiszka <jan.kiszka@siemens.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Anthony Liguori <aliguori@us.ibm.com>,
Marcel Apfelbaum <marcel.a@redhat.com>,
QEMU Developers <qemu-devel@nongnu.org>,
"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses
Date: Mon, 09 Sep 2013 19:09:34 +0200 [thread overview]
Message-ID: <522E00CE.9050400@siemens.com> (raw)
In-Reply-To: <CAFEAcA9xy72eoYGh9EPzLp9x415nd7AQnKr+A+rBGaUQ-DMbTg@mail.gmail.com>
On 2013-09-09 18:58, Peter Maydell wrote:
> On 9 September 2013 17:54, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>> DMA requests from one device to another targeting anything else but
>> RAM-backed regions will have to be rejected by QEMU in the future. We
>> cannot map this sanely on a per-device locking model. The filtering will
>> take place early in the memory core, to avoid any risk of deadlocking.
>> No idea if reporting them as aborts will be easily feasible then.
>
> Why is a DMA request any different from any other communication
> between two devices?
Other communication between devices requiring to take the target
device's lock while holding the one of the initiator will be a no-go as
well. But usually these scenarios are clearly defined, not
guest-influenceable and can be avoided by the initiator. DMA is too
generic. E.g., the guest can easily program a device to "accidentally"
hit another device's MMIO region, creating the precondition for
deadlocks on the host side.
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux
next prev parent reply other threads:[~2013-09-09 17:09 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-09 11:11 [Qemu-devel] [PATCH RFC v2 0/3] pci: complete master abort protocol Marcel Apfelbaum
2013-09-09 11:11 ` [Qemu-devel] [PATCH RFC v2 1/2] memory: allow MemoryRegion's priority field to accept negative values Marcel Apfelbaum
2013-09-09 11:28 ` Peter Maydell
2013-09-09 12:03 ` Marcel Apfelbaum
2013-09-09 11:11 ` [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses Marcel Apfelbaum
2013-09-09 11:40 ` Michael S. Tsirkin
2013-09-09 12:11 ` Marcel Apfelbaum
2013-09-09 12:23 ` Michael S. Tsirkin
2013-09-09 12:43 ` Marcel Apfelbaum
2013-09-09 12:52 ` Peter Maydell
2013-09-09 12:59 ` Michael S. Tsirkin
2013-09-09 13:02 ` Peter Maydell
2013-09-09 13:15 ` Marcel Apfelbaum
2013-09-09 13:19 ` Peter Maydell
2013-09-09 13:29 ` Marcel Apfelbaum
2013-09-09 13:39 ` Peter Maydell
2013-09-09 14:04 ` Marcel Apfelbaum
2013-09-09 14:21 ` Peter Maydell
2013-09-09 14:51 ` Marcel Apfelbaum
2013-09-09 14:58 ` Peter Maydell
2013-09-09 16:00 ` Michael S. Tsirkin
2013-09-09 16:02 ` Peter Maydell
2013-09-09 16:34 ` Michael S. Tsirkin
2013-09-09 16:54 ` Jan Kiszka
2013-09-09 16:58 ` Peter Maydell
2013-09-09 17:09 ` Jan Kiszka [this message]
2013-09-09 17:14 ` Peter Maydell
2013-09-09 17:27 ` Jan Kiszka
2013-09-09 17:37 ` Michael S. Tsirkin
2013-09-09 17:41 ` Peter Maydell
2013-09-09 18:06 ` Jan Kiszka
2013-09-09 18:11 ` Paolo Bonzini
2013-09-09 19:35 ` Michael S. Tsirkin
2013-09-09 18:03 ` Paolo Bonzini
2013-09-09 18:49 ` Jan Kiszka
2013-09-09 18:59 ` Peter Maydell
2013-09-09 19:04 ` Jan Kiszka
2013-09-09 19:27 ` Michael S. Tsirkin
2013-09-09 19:31 ` Michael S. Tsirkin
2013-09-09 15:54 ` Michael S. Tsirkin
2013-09-09 14:04 ` Michael S. Tsirkin
2013-09-09 14:16 ` Marcel Apfelbaum
2013-09-09 13:59 ` Michael S. Tsirkin
2013-09-09 13:07 ` Marcel Apfelbaum
2013-09-09 13:16 ` Peter Maydell
2013-09-09 13:44 ` Marcel Apfelbaum
2013-09-10 12:39 ` Michael S. Tsirkin
2013-09-10 12:50 ` Peter Maydell
2013-09-10 13:02 ` Michael S. Tsirkin
2013-09-10 13:12 ` Peter Maydell
2013-09-10 14:11 ` Michael S. Tsirkin
2013-09-15 7:14 ` Michael S. Tsirkin
2013-09-15 10:56 ` Peter Maydell
2013-09-15 11:05 ` Michael S. Tsirkin
2013-09-15 11:23 ` Peter Maydell
2013-09-15 12:17 ` Michael S. Tsirkin
2013-09-15 13:24 ` Peter Maydell
2013-09-15 13:39 ` Michael S. Tsirkin
2013-09-15 13:49 ` Peter Maydell
2013-09-15 14:08 ` Michael S. Tsirkin
2013-09-15 14:08 ` Peter Maydell
2013-09-15 14:20 ` Michael S. Tsirkin
2013-09-15 14:49 ` Peter Maydell
2013-09-15 15:05 ` Michael S. Tsirkin
2013-09-15 15:08 ` Peter Maydell
2013-09-15 15:31 ` Michael S. Tsirkin
2013-09-15 17:12 ` Peter Maydell
2013-09-15 9:29 ` Marcel Apfelbaum
2013-09-09 14:01 ` Michael S. Tsirkin
2013-09-09 13:58 ` Michael S. Tsirkin
2013-09-09 14:10 ` Marcel Apfelbaum
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