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Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addres
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses |
Date: |
Mon, 09 Sep 2013 19:09:34 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2013-09-09 18:58, Peter Maydell wrote:
> On 9 September 2013 17:54, Jan Kiszka <address@hidden> 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
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, (continued)
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Peter Maydell, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Marcel Apfelbaum, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Peter Maydell, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Marcel Apfelbaum, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Peter Maydell, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Michael S. Tsirkin, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Peter Maydell, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Michael S. Tsirkin, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Jan Kiszka, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Peter Maydell, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses,
Jan Kiszka <=
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Peter Maydell, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Jan Kiszka, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Michael S. Tsirkin, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Peter Maydell, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Jan Kiszka, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Paolo Bonzini, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Michael S. Tsirkin, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Paolo Bonzini, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Jan Kiszka, 2013/09/09
- Re: [Qemu-devel] [PATCH RFC v2 2/2] hw/pci: handle unassigned pci addresses, Peter Maydell, 2013/09/09