Re: [kvm-unit-tests patch v3 5/8] x86/pmu: Relax precise count check for emulated instructions tests

Sean Christopherson
2025-11-20T22:29:12Z

On Wed, Sep 03, 2025, Dapeng Mi wrote:
> Relax precise count check for emulated instructions tests on these
> platforms with HW overcount issues.
>
> Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
> ---
> x86/pmu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/x86/pmu.c b/x86/pmu.c
> index c54c0988..6bf6eee3 100644
> --- a/x86/pmu.c
> +++ b/x86/pmu.c
> @@ -790,7 +790,7 @@ static void check_emulated_instr(void)
>
> // Check that the end count - start count is at least the expected
> // number of instructions and branches.
> - if (this_cpu_has_perf_global_ctrl()) {
> + if (this_cpu_has_perf_global_ctrl() && !intel_inst_overcount_flags) {

This skips precise checking if _either_ errata is present. IIUC, we can still do
a precise check for branches retired on Clearwater Forest, but not for instructions
retired.

> report(instr_cnt.count - instr_start == KVM_FEP_INSNS,
> "instruction count");
> report(brnch_cnt.count - brnch_start == KVM_FEP_BRANCHES,
> --
> 2.34.1
>