Re: [PATCH 12/14] i386/cpu: Store LAPIC bus frequency in CPU structure

[Michael S. Tsirkin]

On Tue, Mar 10, 2020 at 01:54:09AM +0200, Liran Alon wrote:
> No functional change.
> This information will be used by following patches.
> 
> Reviewed-by: Nikita Leshenko <address@hidden>
> Signed-off-by: Liran Alon <address@hidden>
> ---
>  linux-headers/asm-x86/kvm.h | 4 ++++
>  target/i386/cpu.h           | 1 +
>  target/i386/kvm.c           | 6 +++---
>  3 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/linux-headers/asm-x86/kvm.h b/linux-headers/asm-x86/kvm.h
> index 503d3f42da16..99eeaaf2f0b4 100644
> --- a/linux-headers/asm-x86/kvm.h
> +++ b/linux-headers/asm-x86/kvm.h
> @@ -446,4 +446,8 @@ struct kvm_pmu_event_filter {
>  #define KVM_PMU_EVENT_ALLOW 0
>  #define KVM_PMU_EVENT_DENY 1
>  
> +/* From arch/x86/kvm/lapic.h */
> +#define KVM_APIC_BUS_CYCLE_NS       1
> +#define KVM_APIC_BUS_FREQUENCY      (1000000000ULL / KVM_APIC_BUS_CYCLE_NS)
> +
>  #endif /* _ASM_X86_KVM_H */


This header is auto-generated from UAPI - you can't add
your own stuff here.


> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 576f309bbfc8..9c7cd7cde107 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -1580,6 +1580,7 @@ typedef struct CPUX86State {
>      bool tsc_valid;
>      int64_t tsc_khz;
>      int64_t user_tsc_khz; /* for sanity check only */
> +    uint64_t apic_bus_freq;
>  #if defined(CONFIG_KVM) || defined(CONFIG_HVF)
>      void *xsave_buf;
>  #endif
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index 69eb43d796e6..00917196dffb 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -1496,6 +1496,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
>          }
>      }
>  
> +    env->apic_bus_freq = KVM_APIC_BUS_FREQUENCY;
> +
>      /* Paravirtualization CPUIDs */
>      r = hyperv_handle_properties(cs, cpuid_data.entries);
>      if (r < 0) {
> @@ -1800,9 +1802,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
>          c = &cpuid_data.entries[cpuid_i++];
>          c->function = KVM_CPUID_SIGNATURE | 0x10;
>          c->eax = env->tsc_khz;
> -        /* LAPIC resolution of 1ns (freq: 1GHz) is hardcoded in KVM's
> -         * APIC_BUS_CYCLE_NS */
> -        c->ebx = 1000000;
> +        c->ebx = env->apic_bus_freq / 1000; /* Hz to KHz */
>          c->ecx = c->edx = 0;
>  
>          c = cpuid_find_entry(&cpuid_data.cpuid, kvm_base, 0);
> -- 
> 2.20.1