From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3sjqc522M2zDrSv for ; Tue, 27 Sep 2016 15:47:33 +1000 (AEST) Date: Tue, 27 Sep 2016 15:45:33 +1000 From: Paul Mackerras To: Thomas Huth Cc: kvm-ppc@vger.kernel.org, kvm@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Michael Ellerman , Alexander Graf , stable@vger.kernel.org Subject: Re: [PATCH] KVM: PPC: Book3s PR: Allow access to unprivileged MMCR2 register Message-ID: <20160927054533.3azixxy77bh6v3om@oak.ozlabs.ibm.com> References: <1474463205-5965-1-git-send-email-thuth@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1474463205-5965-1-git-send-email-thuth@redhat.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Sep 21, 2016 at 03:06:45PM +0200, Thomas Huth wrote: > The MMCR2 register is available twice, one time with number 785 > (privileged access), and one time with number 769 (unprivileged, > but it can be disabled completely). In former times, the Linux > kernel was using the unprivileged register 769 only, but since > commit 8dd75ccb571f3c92c ("powerpc: Use privileged SPR number > for MMCR2"), it uses the privileged register 785 instead. > The KVM-PR code then of course also switched to use the SPR 785, > but this is causing older guest kernels to crash, since these > kernels still access 769 instead. So to support older kernels > with KVM-PR again, we have to support register 769 in KVM-PR, too. > > Fixes: 8dd75ccb571f3c92c48014b3dabd3d51a115ab41 > Cc: stable@vger.kernel.org # v3.10+ > Signed-off-by: Thomas Huth Thanks, applied to kvm-ppc-next. Paul.