From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41805) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eQtrk-0002vf-OW for qemu-devel@nongnu.org; Mon, 18 Dec 2017 06:45:53 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eQtrh-000453-Kx for qemu-devel@nongnu.org; Mon, 18 Dec 2017 06:45:52 -0500 Received: from 12.mo1.mail-out.ovh.net ([87.98.162.229]:47065) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eQtrh-00044U-Ec for qemu-devel@nongnu.org; Mon, 18 Dec 2017 06:45:49 -0500 Received: from player691.ha.ovh.net (gw6.ovh.net [213.251.189.206]) by mo1.mail-out.ovh.net (Postfix) with ESMTP id B6EA8B26D8 for ; Mon, 18 Dec 2017 12:45:47 +0100 (CET) Date: Mon, 18 Dec 2017 12:45:40 +0100 From: Greg Kurz Message-ID: <20171218124540.7da45454@bahia.lan> In-Reply-To: <20171218092024.21645-5-david@gibson.dropbear.id.au> References: <20171218092024.21645-1-david@gibson.dropbear.id.au> <20171218092024.21645-5-david@gibson.dropbear.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 4/6] target/ppc: Clean up probing of VMX, VSX and DFP availability on KVM List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: surajjs@au1.ibm.com, lvivier@redhat.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com, abologna@redhat.com On Mon, 18 Dec 2017 20:20:22 +1100 David Gibson wrote: > When constructing the "host" cpu class we modify whether the VMX and VSX > vector extensions and DFP (Decimal Floating Point) are available > based on whether KVM can support those instructions. This can depend on > policy in the host kernel as well as on the actual host cpu capabilities. > > However, the way we probe for this is not very nice: we explicitly check > the host's device tree. That works in practice, but it's not really > correct, since the device tree is a property of the host kernel's platform > which we don't really know about. We get away with it because the only > modern POWER platforms happen to encode VMX, VSX and DFP availability in > the device tree in the same way. > > Arguably we should have an explicit KVM capability for this, but we haven't > needed one so far. Barring specific KVM policies which don't yet exist, > each of these instruction classes will be available in the guest if and > only if they're available in the qemu userspace process. We can determine > that from the ELF AUX vector we're supplied with. > > Once reworked like this, there are no more callers for kvmppc_get_vmx() and > kvmppc_get_dfp() so remove them. > > Signed-off-by: David Gibson > --- Reviewed-by: Greg Kurz > target/ppc/kvm.c | 27 ++++++--------------------- > target/ppc/kvm_ppc.h | 2 -- > 2 files changed, 6 insertions(+), 23 deletions(-) > > diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c > index 9d57debf0e..81d9bd56c7 100644 > --- a/target/ppc/kvm.c > +++ b/target/ppc/kvm.c > @@ -2014,16 +2014,6 @@ uint64_t kvmppc_get_clockfreq(void) > return kvmppc_read_int_cpu_dt("clock-frequency"); > } > > -uint32_t kvmppc_get_vmx(void) > -{ > - return kvmppc_read_int_cpu_dt("ibm,vmx"); > -} > - > -uint32_t kvmppc_get_dfp(void) > -{ > - return kvmppc_read_int_cpu_dt("ibm,dfp"); > -} > - > static int kvmppc_get_pvinfo(CPUPPCState *env, struct kvm_ppc_pvinfo *pvinfo) > { > PowerPCCPU *cpu = ppc_env_get_cpu(env); > @@ -2407,23 +2397,18 @@ static void alter_insns(uint64_t *word, uint64_t flags, bool on) > static void kvmppc_host_cpu_class_init(ObjectClass *oc, void *data) > { > PowerPCCPUClass *pcc = POWERPC_CPU_CLASS(oc); > - uint32_t vmx = kvmppc_get_vmx(); > - uint32_t dfp = kvmppc_get_dfp(); > uint32_t dcache_size = kvmppc_read_int_cpu_dt("d-cache-size"); > uint32_t icache_size = kvmppc_read_int_cpu_dt("i-cache-size"); > > /* Now fix up the class with information we can query from the host */ > pcc->pvr = mfpvr(); > > - if (vmx != -1) { > - /* Only override when we know what the host supports */ > - alter_insns(&pcc->insns_flags, PPC_ALTIVEC, vmx > 0); > - alter_insns(&pcc->insns_flags2, PPC2_VSX, vmx > 1); > - } > - if (dfp != -1) { > - /* Only override when we know what the host supports */ > - alter_insns(&pcc->insns_flags2, PPC2_DFP, dfp); > - } > + alter_insns(&pcc->insns_flags, PPC_ALTIVEC, > + qemu_getauxval(AT_HWCAP) & PPC_FEATURE_HAS_ALTIVEC); > + alter_insns(&pcc->insns_flags2, PPC2_VSX, > + qemu_getauxval(AT_HWCAP) & PPC_FEATURE_HAS_VSX); > + alter_insns(&pcc->insns_flags2, PPC2_DFP, > + qemu_getauxval(AT_HWCAP) & PPC_FEATURE_HAS_DFP); > > if (dcache_size != -1) { > pcc->l1_dcache_size = dcache_size; > diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h > index d6be38ecaf..ecb55493cc 100644 > --- a/target/ppc/kvm_ppc.h > +++ b/target/ppc/kvm_ppc.h > @@ -15,8 +15,6 @@ > > uint32_t kvmppc_get_tbfreq(void); > uint64_t kvmppc_get_clockfreq(void); > -uint32_t kvmppc_get_vmx(void); > -uint32_t kvmppc_get_dfp(void); > bool kvmppc_get_host_model(char **buf); > bool kvmppc_get_host_serial(char **buf); > int kvmppc_get_hasidle(CPUPPCState *env);