Re: [Xen-devel] [PATCH v2 4/4] x86/vvmx: correctly emulate VMREAD

[Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>]

On Tue, 2017-02-07 at 06:52 +0000, Tian, Kevin wrote:
> > From: Sergey Dyasli [mailto:sergey.dyasli@xxxxxxxxxx]
> > Sent: Monday, February 06, 2017 10:58 PM
> > 
> > There is an issue with the original __vmread() in nested vmx mode:
> > emulation of a guest's VMREAD with invalid arguments leads to BUG().
> > 
> > Fix this by using vmread_safe() and reporting any kind of VMfail back
> > to the guest.
> > 
> > A new safe versions of get_vvmcs() macro and related functions are
> > introduced because of new function signatures and lots of existing
> > users.
> > 
> > Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
> 
> after reading this patch I realized my earlier ack to 3/4 might not hold,
> since now you have mismatched get/set pairs:
> 
> get_vvmcs
> get_vvmcs_safe
> set_vvmcs
> 
> suggest to also introduce a set_vvmcs_safe counterpart in 3/4, as
> there are still many existing callers on set_vvmcs which don't 
> expect error.

It is true that my patch introduces a change in behaviour: invalid
set_vvmcs() calls will silently fail instead of triggering BUG().
I agree it would be better to introduce set_vvmcs_safe() for now.

-- 
Thanks,
Sergey
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