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. -- Vitaly
