Wanpeng Li <kernellwp@xxxxxxxxx> writes: > 2018-05-18 20:42 GMT+08:00 Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>: >> Wanpeng Li <kernellwp@xxxxxxxxx> writes: >> >>> 2018-05-18 19:19 GMT+08:00 Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>: >>>> Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> writes: >>>> >>>>> Wanpeng Li <kernellwp@xxxxxxxxx> writes: >>>>> >>>>>> Hi Vitaly, >>>>>> 2018-05-16 23:21 GMT+08:00 Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>: >>>>>>> Changes since v3 [Radim Krcmar]: >>>>>>> - PATCH2 fixing 'HV_GENERIC_SET_SPARCE_4K' typo added. >>>>>>> - PATCH5 introducing kvm_make_vcpus_request_mask() API added. >>>>>>> - Fix undefined behavior for hv->vp_index >= 64. >>>>>>> - Merge kvm_hv_flush_tlb() and kvm_hv_flush_tlb_ex() >>>>>>> - For -ex case preload all banks with a single kvm_read_guest(). >>>>>>> >>>>>>> Description: >>>>>>> >>>>>>> This is both a new feature and a bugfix. >>>>>>> >>>>>>> Bugfix description: >>>>>>> >>>>>>> It was found that Windows 2016 guests on KVM crash when they have > 64 >>>>>>> vCPUs, non-flat topology (>1 core/thread per socket; in case it has >64 >>>>>>> sockets Windows just ignores vCPUs above 64) and Hyper-V enlightenments >>>>>> >>>>>> We try the below command line, the Windows 2016 guest successfully to >>>>>> login and there are 80 vCPUs can be observed in the guest w/o the >>>>>> patchset, why you mentioned the crash and ignore? >>>>>> >>>>>> /usr/local/bin/qemu-system-x86_64 -machine pc-i440fx-rhel7.3.0 -m >>>>>> 8192 -smp 80,sockets=2,cores=40,threads=1 -device >>>>>> ide-drive,bus=ide.0,drive=test -drive >>>>>> id=test,if=none,file=/instanceimage/359b18ab-05bb-460d-9b53-89505bca68ed/359b18ab-05bb-460d-9b53-89505bca68ed_vda_1.qcow2 >>>>>> -net nic,model=virtio -net user -monitor stdio -usb -usbdevice tablet >>>>>> --enable-kvm --cpu host -vnc 0.0.0.0:2 >>>>> >>>>> Crash happens when you manifest yourself as Hyper-V, you can do this by >>>>> adding any 'hv-*' feature (e.g. try '-cpu host,hv_vpindex'). >>>> >>>> Oh, and the 'ignore' happens when you pass more than 64 sockets >>>> (somthing like "-smp 128,sockets=128,cores=1,threads=1") -- and this >>>> happens regardless of Hyper-V enlightenments. But I guess it's just >>>> because Windows doesn't support more than 64 sockets. >>> >>> Is there an option in the guest to avoid to check pvtlb support in hyperv? >>> >> >> You mean to tell Windows to not use PV TLB flush when it's available? I >> have no idea. My guess would be that it's left up to the hypervisor: if >> the feature is available Windows will use it. > > I mean a way to work around Windows guest crash since there is no PV > TLB flush enabled in product environment currently. > Unfortunately I don't know of such option, all real Hyper-V servers support it so I think nodoby ever tested how Windows behaves without it. I did and oops, it crashes... -- Vitaly
