Re: [PATCH] Fix possible FPU information on SVM

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Joerg Roedel wrote:
> From: Joerg Roedel <joerg.roedel-5C7GfCeVMHo@public.gmane.org>
>
> On AMD K8 processors the fxsave/fxrstor instructions do not save and
> restore the x87 error pointers FIP/FOP and FDP except the ES bit in the
> status word is set. This could lead to information leakage from host to
> guest and vice versa. This patch fixes this by setting the error
> pointers to defined values on FPU state switch in KVM.
>
>   

The host already has full access to the guest fpu state, so there's no 
gain in clearing the error pointers after the guest exit.  Am I right in 
assuming that the error data itself cannot cause any problems?

The first bit (before guest entry) is needed, though I have a hard time 
seeing what a guest could to with the error pointers.


-- 
error compiling committee.c: too many arguments to function


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