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.Virtual machines using `Cooperlake` cannot boot when `TSX` is disabled on the host
Virtual machines (VMs) that use the `Cooperlake` CPU model currently fail to boot when the `TSX` CPU flag is diabled on the host. Instead, the host displays the following error message:
----
the CPU is incompatible with host CPU: Host CPU does not provide required features: hle, rtm
----
To make VMs with `Cooperlake` usable on such host, disable the HLE, RTM, and TAA_NO flags in the VM configuration in the VM's XML configuration:
----
<feature policy='disable' name='hle'/>
<feature policy='disable' name='rtm'/>
<feature policy='disable' name='taa-no'/>
----
Can you clarify why this is a regression? If the CPU model already includes TSX and the host disables TSX by default now, there's not much we can do. We can't change the existing CPU model because it would break guest ABI.
Can you check what's the result of CPU model='host-model' on that host? We won't change the CPU model in QEMU, but we do want to make sure libvirt makes it easy to deal with the removed feature.
(In reply to Eduardo Habkost from comment #9)
Hi, I just get the Cooperlake-Server machine.
> Can you clarify why this is a regression? If the CPU model already includes
> TSX and the host disables TSX by default now, there's not much we can do.
> We can't change the existing CPU model because it would break guest ABI.
>
I have no problem with TSX.
And for "taa-no" since we have planed to disable it just like TSX I think we can remove the Regression word.Thanks.
> Can you check what's the result of CPU model='host-model' on that host? We
> won't change the CPU model in QEMU, but we do want to make sure libvirt
> makes it easy to deal with the removed feature.
For CPU model='host-model' in xml, libvirt disables the flag hle, rtm, taa-no.
<cpu mode='custom' match='exact' check='full'>
<model fallback='forbid'>Cooperlake</model>
<vendor>Intel</vendor>
<feature policy='require' name='ss'/>
<feature policy='require' name='vmx'/>
<feature policy='require' name='hypervisor'/>
<feature policy='require' name='tsc_adjust'/>
<feature policy='require' name='mpx'/>
<feature policy='require' name='umip'/>
<feature policy='require' name='md-clear'/>
<feature policy='require' name='xsaves'/>
<feature policy='require' name='ibpb'/>
<feature policy='require' name='amd-ssbd'/>
<feature policy='disable' name='hle'/>
<feature policy='disable' name='rtm'/>
<feature policy='disable' name='taa-no'/>
</cpu>
Test environments:
intel-cedarisland-01.khw1.lab.eng.bos.redhat.com
qemu-kvm-4.2.0-33.module+el8.3.0+7705+f09d73e4.x86_64
kernel-4.18.0-234.el8.x86_64
And I will disable the "taa-no" manually with "-cpu Cooperlake,-taa-no,-hle,-rtm,enforce" as Doc Text said to use Cooperlake-Server cpu model now, thanks.
Best regards
Liu Nana
Just found this old BZ on my BZ list.
(In reply to liunana from comment #10)
> For CPU model='host-model' in xml, libvirt disables the flag hle, rtm,
> taa-no.
>
> <cpu mode='custom' match='exact' check='full'>
> <model fallback='forbid'>Cooperlake</model>
> <vendor>Intel</vendor>
> <feature policy='require' name='ss'/>
> <feature policy='require' name='vmx'/>
> <feature policy='require' name='hypervisor'/>
> <feature policy='require' name='tsc_adjust'/>
> <feature policy='require' name='mpx'/>
> <feature policy='require' name='umip'/>
> <feature policy='require' name='md-clear'/>
> <feature policy='require' name='xsaves'/>
> <feature policy='require' name='ibpb'/>
> <feature policy='require' name='amd-ssbd'/>
> <feature policy='disable' name='hle'/>
> <feature policy='disable' name='rtm'/>
> <feature policy='disable' name='taa-no'/>
> </cpu>
>
> Test environments:
> intel-cedarisland-01.khw1.lab.eng.bos.redhat.com
> qemu-kvm-4.2.0-33.module+el8.3.0+7705+f09d73e4.x86_64
> kernel-4.18.0-234.el8.x86_64
>
>
> And I will disable the "taa-no" manually with "-cpu
> Cooperlake,-taa-no,-hle,-rtm,enforce" as Doc Text said to use
> Cooperlake-Server cpu model now, thanks.
As libvirt does the right thing when TSX is disabled by the OS vendor or system administrator, closing this as NOTABUG.
See also:
https://lore.kernel.org/qemu-devel/20200825140145.GU642093@habkost.net/
Description of problem: qemu promote host does not support requested feature: MSR(10AH).taa-no [bit 8] on cooperlake machine Version-Release number of selected component (if applicable): Host kernel-4.18.0-227.el8.x86_64 (old qemu) qemu-kvm-4.2.0-25.module+el8.3.0+6986+29a4dcd7 (new qemu) qemu-kvm-4.2.0-31.module+el8.3.0+7437+4bb96e0d seabios-1.13.0-2.module+el8.3.0+7353+9de0a3cc.x86_64 How reproducible: 100% Steps to Reproduce: 1. # /usr/libexec/qemu-kvm -M q35 -cpu Cooperlake,enforce qemu-kvm: warning: host doesn't support requested feature: CPUID.07H:EBX.hle [bit 4] qemu-kvm: warning: host doesn't support requested feature: CPUID.07H:EBX.rtm [bit 11] qemu-kvm: warning: host doesn't support requested feature: MSR(10AH).taa-no [bit 8] qemu-kvm: Host doesn't support requested features Actual results: qemu can't boot with warning message. Expected results: qemu can boot without error. Additional info: Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 144 On-line CPU(s) list: 0-143 Thread(s) per core: 2 Core(s) per socket: 18 Socket(s): 4 NUMA node(s): 4 Vendor ID: GenuineIntel CPU family: 6 Model: 85 Model name: Intel(R) Xeon(R) Platinum 8353H CPU @ 2.50GHz Stepping: 11 CPU MHz: 2653.393 CPU max MHz: 3800.0000 CPU min MHz: 1000.0000 BogoMIPS: 5000.00 Virtualization: VT-x L1d cache: 32K L1i cache: 32K L2 cache: 1024K L3 cache: 25344K NUMA node0 CPU(s): 0-17,72-89 NUMA node1 CPU(s): 18-35,90-107 NUMA node2 CPU(s): 36-53,108-125 NUMA node3 CPU(s): 54-71,126-143 Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 invpcid_single intel_ppin ssbd mba ibrs ibpb stibp ibrs_enhanced tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local avx512_bf16 dtherm ida arat pln pts hwp hwp_act_window hwp_epp hwp_pkg_req pku ospke avx512_vnni md_clear flush_l1d arch_capabilities