From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40553) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fkQU4-00016E-NH for qemu-devel@nongnu.org; Tue, 31 Jul 2018 04:58:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fkQU1-0001O5-99 for qemu-devel@nongnu.org; Tue, 31 Jul 2018 04:58:24 -0400 Date: Tue, 31 Jul 2018 10:58:15 +0200 From: Cornelia Huck Message-ID: <20180731105815.3a6fc0e9.cohuck@redhat.com> In-Reply-To: <20180731084236.184728-1-frankja@linux.ibm.com> References: <20180731084236.184728-1-frankja@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] s390x: Enable KVM huge page backing support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Janosch Frank Cc: qemu-devel@nongnu.org, borntraeger@de.ibm.com, david@redhat.com, qemu-s390x@nongnu.org On Tue, 31 Jul 2018 09:42:36 +0100 Janosch Frank wrote: > From: Janosch Frank > > QEMU has had huge page support for a longer time already, but KVM > memory management under s390x needed some changes to work with huge > backings. > > Now that we have support, let's enable it if requested and > available. Otherwise we now properly tell the user if there is no > support and back out instead of failing to run the VM later on. > > Signed-off-by: Janosch Frank You may want to change author and signoff to the new, shorter address. > --- > > Right now there's a conflict with arm for the capability, so I guess > I'll have to touch the cap number soonish. :) You can fix this by spitting out the linux-headers update into a patch that will be replaced with a proper headers update :) > > --- > linux-headers/linux/kvm.h | 1 + > target/s390x/kvm.c | 6 ++++++ > 2 files changed, 7 insertions(+) > > diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h > index 98f389a5a3..e3b1e3070c 100644 > --- a/linux-headers/linux/kvm.h > +++ b/linux-headers/linux/kvm.h > @@ -949,6 +949,7 @@ struct kvm_ppc_resize_hpt { > #define KVM_CAP_GET_MSR_FEATURES 153 > #define KVM_CAP_HYPERV_EVENTFD 154 > #define KVM_CAP_HYPERV_TLBFLUSH 155 > +#define KVM_CAP_S390_HPAGE 156 > > #ifdef KVM_CAP_IRQ_ROUTING > > diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c > index d923cf4240..1ce0b42039 100644 > --- a/target/s390x/kvm.c > +++ b/target/s390x/kvm.c > @@ -285,6 +285,12 @@ int kvm_arch_init(MachineState *ms, KVMState *s) > { > MachineClass *mc = MACHINE_GET_CLASS(ms); > > + if (mem_path && kvm_vm_enable_cap(s, KVM_CAP_S390_HPAGE, 0)) { > + error_report("Huge page backing was specified, " > + "but this KVM does not support huge pages."); Please drop the trailing '.', as by the documentation for error_report(). > + return -EINVAL; > + } > + > mc->default_cpu_type = S390_CPU_TYPE_NAME("host"); > cap_sync_regs = kvm_check_extension(s, KVM_CAP_SYNC_REGS); > cap_async_pf = kvm_check_extension(s, KVM_CAP_ASYNC_PF);