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Date: Tue, 21 Apr 2015 08:52:36 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 00/18] virtio-blk: Support
	"VIRTIO_CONFIG_S_NEEDS_RESET"
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Fam Zheng <famz@redhat.com>, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>, Stefan Hajnoczi <stefanha@redhat.com>, Amit Shah <amit.shah@redhat.com>



On 20/04/2015 22:34, Michael S. Tsirkin wrote:
> On Mon, Apr 20, 2015 at 09:10:02PM +0200, Paolo Bonzini wrote:
>>
>>
>> On 20/04/2015 19:36, Michael S. Tsirkin wrote:
>>> At the implementation level, there's one big issue you seem to have
>>> missed: DMA to invalid memory addresses causes a crash in memory core.
>>> I'm not sure whether it makes sense to recover from virtio core bugs
>>> when we can't recover from device bugs.
>>
>> What do you mean exactly?  DMA to invalid memory addresses causes
>> address_space_map to return a "short read".
>>
>> Paolo
> 
> I mean, first of all, a bunch of virtio_XXX_phys calls.
> These eventually call qemu_get_ram_ptr, which internally calls
> qemu_get_ram_block and ramblock_ptr.
> Both abort on errors.

address_space_translate and memory_access_size should ensure they don't.

Paolo