[RFC PATCH 07/10] KVM: PPC: BOOK3S: PR: Emulate facility status and control register

[Paul Mackerras]

On Tue, Jan 28, 2014 at 10:14:12PM +0530, Aneesh Kumar K.V wrote:
> We allow priv-mode update of this. The guest value is saved in fscr,
> and the value actually used is saved in shadow_fscr. shadow_fscr
> only contains values that are allowed by the host. On
> facility unavailable interrupt, if the facility is allowed by fscr
> but disabled in shadow_fscr we need to emulate the support. Currently
> all but EBB is disabled. We still don't support performance monitoring
> in PR guest.

...

> +	/*
> +	 * Save the current fscr in shadow fscr
> +	 */
> +	mfspr r3,SPRN_FSCR
> +	PPC_STL r3, VCPU_SHADOW_FSCR(r7)

I don't think you need to do this.  What could possibly have changed
FSCR since we loaded it on the way into the guest?

Paul.