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Re: [Qemu-devel] [RFC 2/2] pc: fix QEMU crashing when more than ~50 memo
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From: |
Michael S. Tsirkin |
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Subject: |
Re: [Qemu-devel] [RFC 2/2] pc: fix QEMU crashing when more than ~50 memory hotplugged |
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Date: |
Wed, 3 Jun 2015 18:30:02 +0200 |
On Wed, Jun 03, 2015 at 06:11:29PM +0200, Paolo Bonzini wrote:
>
>
> On 03/06/2015 17:23, Igor Mammedov wrote:
> >> > Understood now. This still should be a separate patch. I'm much more
> >> > confident with the other two (e.g. what happens if a malicious guest
> >> > writes to memory that is still MAP_NORESERVE),
> > it should get SIGSEVG due to access to PROT_NONE.
>
> QEMU doesn't get the SEGV if you do address_space_rw or
> address_space_map to unallocated space, because the empty area in the
> container is treated as MMIO.
>
> But what does vhost do if you tell it to treat the whole block as a
> single huge lump?
>
> Paolo
Guest can make vhost attempt reading or writing it.
vhost will do copy from/to user.
> >> > so feel free to post
> >> > those without RFC tag. But the vhost one really needs mst's eyes.
> > ok, I'll split it out.
> >
Re: [Qemu-devel] [RFC 0/2] Fix QEMU crash during memory hotplug with vhost=on, Michael S. Tsirkin, 2015/06/03