From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Mackerras Date: Fri, 07 Dec 2018 11:42:12 +0000 Subject: Re: [PATCH] KVM: PPC: Book3S PR: Set hflag to indicate that POWER9 supports 1T segments Message-Id: <20181207114212.GA23129@blackberry> List-Id: References: <20181207034326.3564-1-sjitindarsingh@gmail.com> <20181207034326.3564-2-sjitindarsingh@gmail.com> <871s6tlhln.fsf@concordia.ellerman.id.au> In-Reply-To: <871s6tlhln.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Michael Ellerman Cc: aik@ozlabs.ru, linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, Suraj Jitindar Singh , kvm@vger.kernel.org On Fri, Dec 07, 2018 at 10:08:20PM +1100, Michael Ellerman wrote: > Suraj Jitindar Singh writes: > > > When booting a kvm-pr guest on a POWER9 machine the following message is > > observed: > > "qemu-system-ppc64: KVM does not support 1TiB segments which guest expects" > > > > This is because the guest is expecting to be able to use 1T segments > > however we don't indicate support for it. This is because we don't set > > the BOOK3S_HFLAG_MULTI_PGSIZE flag in the hflags in kvmppc_set_pvr_pr() > > on POWER9. > > > > POWER9 does indeed have support for 1T segments, so add a case for > > POWER9 to the switch statement to ensure it is set. > > If this just checked mmu_has_feature(MMU_FTR_1T_SEGMENT) it would have > been right in this case, and we'd also never have to update it in > future. > > Any reason not to? PR KVM can emulate a different processor from the host. Checking mmu_has_feature() will tell you about the host, not the CPU being emulated. Paul.