On 13.09.19 09:46, Thomas Huth wrote:
> Since QEMU v2.10, the KVM acceleration does not work on older kernels
> anymore since the code accidentally requires the KVM_CAP_DEVICE_CTRL
> capability now - it should have been optional instead.
> Instead of fixing the bug, we asked in the ChangeLog of QEMU 2.11 - 3.0
> that people should speak up if they still need support of QEMU running
> with KVM on older kernels, but seems like nobody really complained.
> Thus let's make this official now and turn it into a proper error
> message, telling the users to use at least kernel 3.15 now.
>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
> hw/intc/s390_flic_kvm.c | 6 ------
> target/s390x/kvm.c | 7 +++++++
> 2 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/hw/intc/s390_flic_kvm.c b/hw/intc/s390_flic_kvm.c
> index 819aa5e198..cedccba8a9 100644
> --- a/hw/intc/s390_flic_kvm.c
> +++ b/hw/intc/s390_flic_kvm.c
> @@ -589,12 +589,6 @@ static void kvm_s390_flic_realize(DeviceState *dev, Error **errp)
> goto fail;
> }
> flic_state->fd = -1;
> - if (!kvm_check_extension(kvm_state, KVM_CAP_DEVICE_CTRL)) {
> - error_setg_errno(&errp_local, errno, "KVM is missing capability"
> - " KVM_CAP_DEVICE_CTRL");
> - trace_flic_no_device_api(errno);
> - goto fail;
> - }
>
> cd.type = KVM_DEV_TYPE_FLIC;
> ret = kvm_vm_ioctl(kvm_state, KVM_CREATE_DEVICE, &cd);
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index cea71ac7c3..97a662ad0e 100644
> --- a/target/s390x/kvm.c
> +++ b/target/s390x/kvm.c
> @@ -316,6 +316,13 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
> MachineClass *mc = MACHINE_GET_CLASS(ms);
>
> mc->default_cpu_type = S390_CPU_TYPE_NAME("host");
> +
> + if (!kvm_check_extension(kvm_state, KVM_CAP_DEVICE_CTRL)) {
> + error_report("KVM is missing capability KVM_CAP_DEVICE_CTRL - "
> + "please use kernel 3.15 or newer");
> + return -1;
> + }
> +
> cap_sync_regs = kvm_check_extension(s, KVM_CAP_SYNC_REGS);
> cap_async_pf = kvm_check_extension(s, KVM_CAP_ASYNC_PF);
> cap_mem_op = kvm_check_extension(s, KVM_CAP_S390_MEM_OP);
>
The tracepoint has to go as well as fat as I can see.
Apart from that, looks good to me.
--
Thanks,
David / dhildenb