Re: [PATCH 11/15] KVM: x86/pmu: Emulate streamlined Freeze-LBR-on-PMI

[Chen, Zide]

On 7/28/2026 2:33 PM, Sean Christopherson wrote:
> On Tue, Jul 07, 2026, Zide Chen wrote:
>> PerfMon v4 streamlined the Freeze-LBR-on-PMI mechanism. When
>> DEBUGCTLMSR_FREEZE_LBRS_ON_PMI is set and a PMI fires, hardware sets
>> IA32_PERF_GLOBAL_STATUS.LBR_Frz instead of clearing DEBUGCTLMSR_LBR.
> 
> But KVM doesn't even support LBRs for the mediated PMU?

Right, we have the Arch LBR patchset in the queue, and I was hesitating
to include this as part of PMU v5 feature completion.

I'll drop this patch and remove the following assignment in next version:

pmu->global_status_rsvd &= ~GLOBAL_STATUS_LBRS_FROZEN;