| Message ID | 20180731084236.184728-1-frankja@linux.ibm.com |
|---|---|
| State | New |
| Headers | show |
| Series | s390x: Enable KVM huge page backing support | expand |
On Tue, 31 Jul 2018 09:42:36 +0100 Janosch Frank <frankja@linux.ibm.com> wrote: > From: Janosch Frank <frankja@linux.vnet.ibm.com> > > 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 <frankja@linux.vnet.ibm.com> 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);
On 31.07.2018 10:42, Janosch Frank wrote: > From: Janosch Frank <frankja@linux.vnet.ibm.com> > > 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 <frankja@linux.vnet.ibm.com> > --- > > Right now there's a conflict with arm for the capability, so I guess > I'll have to touch the cap number soonish. :) > > --- > 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."); > + 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); > Okay, I wonder if now is the right time to actually detect the pagesize instead of relying on mempath pointing at hugetlbfs. I remember Power already doing such a detection. mempath is just an indicator.
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."); + 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);