Re: [PATCH v2 27/54] KVM: x86/pmu: Exclude PMU MSRs in vmx_get_passthrough_msr_slot()

Mi, Dapeng
2024-05-14T07:34:55Z

On 5/6/2024 1:29 PM, Mingwei Zhang wrote:
> Reject PMU MSRs interception explicitly in
> vmx_get_passthrough_msr_slot() since interception of PMU MSRs are
> specially handled in intel_passthrough_pmu_msrs().
>
> Signed-off-by: Mingwei Zhang <mizhang@google.com>
> Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
> ---
> arch/x86/kvm/vmx/vmx.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index c9de7d2623b8..62b5913abdd6 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -164,7 +164,7 @@ module_param(enable_passthrough_pmu, bool, 0444);
>
> /*
> * List of MSRs that can be directly passed to the guest.
> - * In addition to these x2apic, PT and LBR MSRs are handled specially.
> + * In addition to these x2apic, PMU, PT and LBR MSRs are handled specially.
> */
> static u32 vmx_possible_passthrough_msrs[MAX_POSSIBLE_PASSTHROUGH_MSRS] = {
> MSR_IA32_SPEC_CTRL,
> @@ -694,6 +694,13 @@ static int vmx_get_passthrough_msr_slot(u32 msr)
> case MSR_LBR_CORE_FROM ... MSR_LBR_CORE_FROM + 8:
> case MSR_LBR_CORE_TO ... MSR_LBR_CORE_TO + 8:
> /* LBR MSRs. These are handled in vmx_update_intercept_for_lbr_msrs() */
> + case MSR_IA32_PMC0 ... MSR_IA32_PMC0 + 7:
> + case MSR_IA32_PERFCTR0 ... MSR_IA32_PERFCTR0 + 7:
> + case MSR_CORE_PERF_FIXED_CTR0 ... MSR_CORE_PERF_FIXED_CTR0 + 2:

We'd better use helpers to get the maximum supported GP and fixed counter
instead of magic numbers here. There are more GP and fixed counters in the
future's Intel CPUs.

> + case MSR_CORE_PERF_GLOBAL_STATUS:
> + case MSR_CORE_PERF_GLOBAL_CTRL:
> + case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
> + /* PMU MSRs. These are handled in intel_passthrough_pmu_msrs() */
> return -ENOENT;
> }
>