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Disable LBR virtualization if the CPU doesn't support callstacks, which were introduced in HSW (see commite9d7f7cd97("perf/x86/intel: Add basic Haswell LBR call stack support"), as KVM unconditionally configures the perf LBR event with PERF_SAMPLE_BRANCH_CALL_STACK, i.e. LBR virtualization always fails on pre-HSW CPUs. Simply disable LBR support on such CPUs, as it has never worked, i.e. there is no risk of breaking an existing setup, and figuring out a way to performantly context switch LBRs on old CPUs is not worth the effort. Fixes:be635e34c2("KVM: vmx/pmu: Expose LBR_FMT in the MSR_IA32_PERF_CAPABILITIES") Cc: Mingwei Zhang <mizhang@google.com> Cc: Jim Mattson <jmattson@google.com> Tested-by: Mingwei Zhang <mizhang@google.com> Link: https://lore.kernel.org/r/20240307011344.835640-4-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>