From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Aneesh Kumar K.V" Date: Fri, 31 Jan 2014 11:40:05 +0000 Subject: Re: [RFC PATCH 07/10] KVM: PPC: BOOK3S: PR: Emulate facility status and control register Message-Id: <87ob2sjsqi.fsf@linux.vnet.ibm.com> List-Id: References: <1390927455-3312-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1390927455-3312-8-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <20140130060000.GB10611@iris.ozlabs.ibm.com> In-Reply-To: <20140130060000.GB10611@iris.ozlabs.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Paul Mackerras Cc: agraf@suse.de, benh@kernel.crashing.org, linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org Paul Mackerras writes: > 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? The reason for facility unavailable interrupt is encoded in FSCR right ? -aneesh