From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:41849) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gmyuY-0000TD-T8 for qemu-devel@nongnu.org; Fri, 25 Jan 2019 05:40:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gmyuW-0004o2-Dw for qemu-devel@nongnu.org; Fri, 25 Jan 2019 05:40:34 -0500 Date: Fri, 25 Jan 2019 11:40:26 +0100 From: Igor Mammedov Message-ID: <20190125114026.66703a35@redhat.com> In-Reply-To: <3b4eef57-dc27-356e-5487-0b9b53a75cb1@redhat.com> References: <1548349076-350255-1-git-send-email-imammedo@redhat.com> <3b4eef57-dc27-356e-5487-0b9b53a75cb1@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] s390x: remove direct reference to mem_path global form s90x code List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Hildenbrand Cc: qemu-devel@nongnu.org, pasic@linux.ibm.com, borntraeger@de.ibm.com, qemu-s390x@nongnu.org, cohuck@redhat.com, rth@twiddle.net On Fri, 25 Jan 2019 09:03:49 +0100 David Hildenbrand wrote: > On 24.01.19 17:57, Igor Mammedov wrote: > > I plan to deprecate -mem-path option and replace it with memory-backend, > > for that it's necessary to get rid of mem_path global variable. > > Do it for s390x case, replacing it with alternative way to enable > > 1Mb hugepages capability. > > > > Signed-off-by: Igor Mammedov > > --- > > PS: > > Original code nor the new one probably is not entirely correct when > > huge pages are enabled in case where mixed initial RAM and memory > > backends are used, backend's page size might not match initial RAM's > > so I'm not sure if enabling 1MB cap is correct in this case on s390 > > (should it be the same for all RAM???). > > With new approach 1Mb cap is not enabled if the smallest page size > > is not 1Mb. > > There is no memory hotplug (DIMM/NVDIMM), so there really only is > initial memory. Ok, but what about coming up virtio-mem? > > --- > > target/s390x/kvm.c | 37 ++++++++++++++++--------------------- > > 1 file changed, 16 insertions(+), 21 deletions(-) > > > > diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c > > index 2ebf26a..22e868a 100644 > > --- a/target/s390x/kvm.c > > +++ b/target/s390x/kvm.c > > @@ -285,33 +285,28 @@ void kvm_s390_crypto_reset(void) > > } > > } > > > > -static int kvm_s390_configure_mempath_backing(KVMState *s) > > +static int kvm_s390_configure_hugepage_backing(KVMState *s) > > { > > - size_t path_psize = qemu_mempath_getpagesize(mem_path); > > + size_t psize = qemu_getrampagesize(); > > > > - if (path_psize == 4 * KiB) { > > if you keep this (modified) check you have to do minimal changes in the > code below. (e.g. not indent error messages) Do you mean to keep this function as is and only s/qemu_mempath_getpagesize(mem_path)/qemu_getrampagesize()/ I'm curious what are possible page sizes are possible on the host for file (hugepage) backed RAM and for anonymous RAM (malloc & co) > > > - return 0; > > - } > > -> - if (!hpage_1m_allowed()) { > > - error_report("This QEMU machine does not support huge page " > > - "mappings"); > > - return -EINVAL; > > - } > > + if (psize == 1 * MiB) { > > + if (!hpage_1m_allowed()) { > > + error_report("This QEMU machine does not support huge page " > > + "mappings"); > > + return -EINVAL; > > + } > > > > - if (path_psize != 1 * MiB) { > > + if (kvm_vm_enable_cap(s, KVM_CAP_S390_HPAGE_1M, 0)) { > > + error_report("Memory backing with 1M pages was specified, " > > + "but KVM does not support this memory backing"); > > + return -EINVAL; > > + } > > + cap_hpage_1m = 1; > > + } else if (psize == 2 * GiB) { > > error_report("Memory backing with 2G pages was specified, " > > "but KVM does not support this memory backing"); > > return -EINVAL; > > } > > - > > - if (kvm_vm_enable_cap(s, KVM_CAP_S390_HPAGE_1M, 0)) { > > - error_report("Memory backing with 1M pages was specified, " > > - "but KVM does not support this memory backing"); > > - return -EINVAL; > > - } > > - > > - cap_hpage_1m = 1; > > return 0; > > } > > > > @@ -319,7 +314,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s) > > { > > MachineClass *mc = MACHINE_GET_CLASS(ms); > > > > - if (mem_path && kvm_s390_configure_mempath_backing(s)) { > > + if (kvm_s390_configure_hugepage_backing(s)) { > > return -EINVAL; > > } > > > > > > Apart from that looks good to me. >