On 24/06/20 03:59, Like Xu wrote:
> Some new Intel platforms (such as TGL) already have the
> fourth fixed counter TOPDOWN.SLOTS, but it has not been
> fully enabled on KVM and the host.
>
> Therefore, we limit edx.split.num_counters_fixed to 3,
> so that it does not break the kvm-unit-tests PMU test
> case and bad-handled userspace.
>
> Signed-off-by: Like Xu <like.xu@xxxxxxxxxxxxxxx>
> ---
> arch/x86/kvm/cpuid.c | 2 +-
> arch/x86/kvm/pmu.h | 2 ++
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 8a294f9747aa..0a2c6d2b4650 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -604,7 +604,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
> eax.split.bit_width = cap.bit_width_gp;
> eax.split.mask_length = cap.events_mask_len;
>
> - edx.split.num_counters_fixed = cap.num_counters_fixed;
> + edx.split.num_counters_fixed = min(cap.num_counters_fixed, MAX_FIXED_COUNTERS);
> edx.split.bit_width_fixed = cap.bit_width_fixed;
> edx.split.reserved = 0;
>
> diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
> index ab85eed8a6cc..067fef51760c 100644
> --- a/arch/x86/kvm/pmu.h
> +++ b/arch/x86/kvm/pmu.h
> @@ -15,6 +15,8 @@
> #define VMWARE_BACKDOOR_PMC_REAL_TIME 0x10001
> #define VMWARE_BACKDOOR_PMC_APPARENT_TIME 0x10002
>
> +#define MAX_FIXED_COUNTERS 3
> +
> struct kvm_event_hw_type_mapping {
> u8 eventsel;
> u8 unit_mask;
>
Queued, thanks.
Paolo
