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Re: [Qemu-devel] Question about qemu firmware configuration (fw_cfg) dev

From: Richard W.M. Jones
Subject: Re: [Qemu-devel] Question about qemu firmware configuration (fw_cfg) device
Date: Mon, 19 Jul 2010 10:23:03 +0100
User-agent: Mutt/1.5.18 (2008-05-17)

On Mon, Jul 19, 2010 at 12:19:22PM +0300, Gleb Natapov wrote:
> Vcpu executes "in %ax". Next instruction is executed 6 seconds later.
> All timers that should have been processed during this time fire at the
> same moment triggering all kind of timeouts. Think about watchdog that
> should be written into every two seconds otherwise it does reset.

This particular code runs very early in boot, and the atomic copy
operation is very quick even with a 100MB initrd.

But the question I think should be: If a guest maliciously (after
boot) tried to use this mechanism, could it do harm to the host?  Or
would it just harm itself?


Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://et.redhat.com/~rjones/libguestfs/
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