In the mail thread there was more On Thu, Aug 7, 2025 at 10:09 AM Xiaoyao Li <[email protected]> wrote: > > So libvirt must first request with "-cpu xxx,pdcm=on" without "pmu=on" > and gets the result that PDCM is filtered (set in cpu->filtered_features[]).
I wanted to also double down on that, trying to check logs what they say about pdcm and pmu exactly. This is with: 1:10.1.0~rc3+ds-2ubuntu1~questingppa1 (which is WITHOUT the revert, more like the normal RC3) The guest gets started at first with this full cpu definition -cpu Cascadelake-Server,vmx=on,pdcm=on,hypervisor=on,ss=on,tsc- adjust=on,fdp-excptn-only=on,zero-fcs-fds=on,mpx=on,umip=on,pku=on,md- clear=on,stibp=on,flush-l1d=on,arch- capabilities=on,xsaves=on,ibpb=on,ibrs=on,amd-stibp=on,amd- ssbd=on,rdctl-no=on,ibrs-all=on,skip-l1dfl-vmentry=on,mds- no=on,pschange-mc-no=on,tsx-ctrl=on,sbdr-ssdp-no=on,psdp-no=on,fb- clear=on,rfds-no=on,vmx-ins-outs=on,vmx-true-ctls=on,vmx-store- lma=on,vmx-activity-hlt=on,vmx-activity-wait-sipi=on,vmx-vmwrite-vmexit- fields=on,vmx-apicv-xapic=on,vmx-ept=on,vmx-desc-exit=on,vmx-rdtscp- exit=on,vmx-apicv-x2apic=on,vmx-vpid=on,vmx-wbinvd-exit=on,vmx- unrestricted-guest=on,vmx-apicv-register=on,vmx-apicv-vid=on,vmx-rdrand- exit=on,vmx-invpcid-exit=on,vmx-vmfunc=on,vmx-shadow-vmcs=on,vmx-rdseed- exit=on,vmx-pml=on,vmx-xsaves=on,vmx-tsc-scaling=on,vmx-ept- execonly=on,vmx-page-walk-4=on,vmx-ept-2mb=on,vmx-ept-1gb=on,vmx- invept=on,vmx-eptad=on,vmx-invept-single-context=on,vmx-invept-all- context=on,vmx-invvpid=on,vmx-invvpid-single-addr=on,vmx-invvpid-all- context=on,vmx-invept-single-context-noglobals=on,vmx-intr-exit=on,vmx- nmi-exit=on,vmx-vnmi=on,vmx-preemption-timer=on,vmx-posted-intr=on,vmx- vintr-pending=on,vmx-tsc-offset=on,vmx-hlt-exit=on,vmx-invlpg- exit=on,vmx-mwait-exit=on,vmx-rdpmc-exit=on,vmx-rdtsc-exit=on,vmx- cr3-load-noexit=on,vmx-cr3-store-noexit=on,vmx-cr8-load-exit=on,vmx- cr8-store-exit=on,vmx-flexpriority=on,vmx-vnmi-pending=on,vmx-movdr- exit=on,vmx-io-exit=on,vmx-io-bitmap=on,vmx-mtf=on,vmx-msr- bitmap=on,vmx-monitor-exit=on,vmx-pause-exit=on,vmx-secondary- ctls=on,vmx-exit-nosave-debugctl=on,vmx-exit-load-perf-global- ctrl=on,vmx-exit-ack-intr=on,vmx-exit-save-pat=on,vmx-exit-load- pat=on,vmx-exit-save-efer=on,vmx-exit-load-efer=on,vmx-exit-save- preemption-timer=on,vmx-exit-clear-bndcfgs=on,vmx-entry-noload- debugctl=on,vmx-entry-ia32e-mode=on,vmx-entry-load-perf-global- ctrl=on,vmx-entry-load-pat=on,vmx-entry-load-efer=on,vmx-entry-load- bndcfgs=on,vmx-eptp-switching=on,hle=off,rtm=off which has "pdcm=on" but does not mention pmu either way. But once qemu starts we see it emit 2025-08-20T08:53:00.514650Z qemu-system-x86_64: warning: This feature is not available due to PMU being disabled: CPUID[eax=01h].ECX.pdcm [bit 15] When I do "virsh start" after "managedsave" I see this: -cpu Cascadelake-Server,vmx=on,pdcm=off,hypervisor=on,ss=on,tsc- adjust=on,fdp-excptn-only=on,zero-fcs-fds=on,mpx=on,umip=on,pku=on,md- clear=on,stibp=on,flush-l1d=on,arch- capabilities=on,xsaves=on,ibpb=on,ibrs=on,amd-stibp=on,amd- ssbd=on,rdctl-no=on,ibrs-all=on,skip-l1dfl-vmentry=on,mds- no=on,pschange-mc-no=on,tsx-ctrl=on,sbdr-ssdp-no=on,psdp-no=on,fb- clear=on,rfds-no=on,vmx-ins-outs=on,vmx-true-ctls=on,vmx-store- lma=on,vmx-activity-hlt=on,vmx-activity-wait-sipi=on,vmx-vmwrite-vmexit- fields=on,vmx-apicv-xapic=on,vmx-ept=on,vmx-desc-exit=on,vmx-rdtscp- exit=on,vmx-apicv-x2apic=on,vmx-vpid=on,vmx-wbinvd-exit=on,vmx- unrestricted-guest=on,vmx-apicv-register=on,vmx-apicv-vid=on,vmx-rdrand- exit=on,vmx-invpcid-exit=on,vmx-vmfunc=on,vmx-shadow-vmcs=on,vmx-rdseed- exit=on,vmx-pml=on,vmx-xsaves=on,vmx-tsc-scaling=on,vmx-ept- execonly=on,vmx-page-walk-4=on,vmx-ept-2mb=on,vmx-ept-1gb=on,vmx- invept=on,vmx-eptad=on,vmx-invept-single-context=on,vmx-invept-all- context=on,vmx-invvpid=on,vmx-invvpid-single-addr=on,vmx-invvpid-all- context=on,vmx-invept-single-context-noglobals=on,vmx-intr-exit=on,vmx- nmi-exit=on,vmx-vnmi=on,vmx-preemption-timer=on,vmx-posted-intr=on,vmx- vintr-pending=on,vmx-tsc-offset=on,vmx-hlt-exit=on,vmx-invlpg- exit=on,vmx-mwait-exit=on,vmx-rdpmc-exit=on,vmx-rdtsc-exit=on,vmx- cr3-load-noexit=on,vmx-cr3-store-noexit=on,vmx-cr8-load-exit=on,vmx- cr8-store-exit=on,vmx-flexpriority=on,vmx-vnmi-pending=on,vmx-movdr- exit=on,vmx-io-exit=on,vmx-io-bitmap=on,vmx-mtf=on,vmx-msr- bitmap=on,vmx-monitor-exit=on,vmx-pause-exit=on,vmx-secondary- ctls=on,vmx-exit-nosave-debugctl=on,vmx-exit-load-perf-global- ctrl=on,vmx-exit-ack-intr=on,vmx-exit-save-pat=on,vmx-exit-load- pat=on,vmx-exit-save-efer=on,vmx-exit-load-efer=on,vmx-exit-save- preemption-timer=on,vmx-exit-clear-bndcfgs=on,vmx-entry-noload- debugctl=on,vmx-entry-ia32e-mode=on,vmx-entry-load-perf-global- ctrl=on,vmx-entry-load-pat=on,vmx-entry-load-efer=on,vmx-entry-load- bndcfgs=on,vmx-eptp-switching=on,hle=off,rtm=off I still get this warning 2025-08-20T08:54:54.477469Z qemu-system-x86_64: warning: This feature is not available due to PMU being disabled: CPUID[eax=01h].ECX.pdcm [bit 15] But more interestingly - in this second start we see libvirt call the guest with pdcm=off So for a yet unknown reason this second start is setting pdcm=off and therefore all that follows is expected. And yep, then we will get error: operation failed: guest CPU doesn't match specification: missing features: pdcm -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2120649 Title: PDCM breakage in qemu 10.1 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/2120649/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
