Re: [PATCH] KVM: SVM: Fix fault-rip on vmsave/vmload emulation

["Roedel, Joerg" <Joerg.Roedel@amd.com>]

On Wed, Apr 06, 2011 at 07:28:24AM -0400, Avi Kivity wrote:
> On 04/06/2011 02:21 PM, Avi Kivity wrote:
> > On 04/06/2011 01:30 PM, Joerg Roedel wrote:
> >> When the emulation of vmload or vmsave fails because the
> >> guest passed an unsupported physical address it gets an #GP
> >> with rip pointing to the instruction after vmsave/vmload.
> >> This is a bug and fixed by this patch.
> >>
> >
> > Applied, thanks.
> >
> 
> btw, I think the actual address check is incorrect, need to check 
> MAXPHYADDR and not hardcoded 0xffff000000000000.

There is a difference. MAX_PHYSADDR_BITS is the maximum Linux can
support while the mask above is the current limit the hardware
supports.
It is the same on real hardware, when rax is >= (1<<48) there is a #GP
(and no intercept if in guest-mode). Here is btw. a difference between
nested-svm and hardware-svm, if rax contains a physical address which is
supported but not backed by RAM the machine will just freeze on real
hardware where as in nested-svm it causes a #GP (should be fine because
the behavior in this case is undefined).

	Joerg

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