Messages in this thread | | | Date | Wed, 24 Sep 2008 21:54:28 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 1/2] VMware detection support for x86 and x86-64 |
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Alok Kataria wrote: > On Wed, 2008-09-24 at 21:38 -0700, H. Peter Anvin wrote: >> Alok kataria wrote: >>> Even if there is anything on that port on native hardware it would >>> work perfectly well and is _safe_. >>> First let me post the code to access this backdoor port (the way it >>> should really be done ) >>> >>> So whenever we query port 0x5658 , with the GETVERSION command (which >>> is the first thing we do with this port), we expect that eax != >>> 0xFFFFFFFF and ebx has a VMWARE specific MAGIC value. Please note >>> that ebx has been initialized to zero in the code above. >>> >> You have no idea what you just did to a real piece of hardware. > Why ? what do you mean ? > ebx is a local variable in the code above that i posted. > Only when on hypervisor will we write the magic value over there. > How can this affect native hardware, i fail to understand. > Please explain. >
You accessed a bloody I/O port!
If you think it's harmless because it was an IN, you're sorely mistaken.
-hpa
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