linux-kernel - Re: [PATCH v2 1/2] KVM: Introduce pv check helpers

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Date:   Mon, 10 Feb 2020 10:38:15 -0500
From:   Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:     Wanpeng Li <kernellwp@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v2 1/2] KVM: Introduce pv check helpers

On Mon, Feb 10, 2020 at 02:37:30PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@...cent.com>
> 
> Introduce some pv check helpers for consistency.
> 
> Suggested-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

Thank you!
> ---
>  arch/x86/kernel/kvm.c | 34 ++++++++++++++++++++++++----------
>  1 file changed, 24 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index d817f25..76ea8c4 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -425,7 +425,27 @@ static void __init sev_map_percpu_data(void)
>      }
>  }
> 
> +static bool pv_tlb_flush_supported(void)
> +{
> +    return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
> +        !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
> +        kvm_para_has_feature(KVM_FEATURE_STEAL_TIME));
> +}
> +
>  #ifdef CONFIG_SMP
> +
> +static bool pv_ipi_supported(void)
> +{
> +    return kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI);
> +}
> +
> +static bool pv_sched_yield_supported(void)
> +{
> +    return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
> +        !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
> +        kvm_para_has_feature(KVM_FEATURE_STEAL_TIME));
> +}
> +
>  #define KVM_IPI_CLUSTER_SIZE    (2 * BITS_PER_LONG)
> 
>  static void __send_ipi_mask(const struct cpumask *mask, int vector)
> @@ -619,9 +639,7 @@ static void __init kvm_guest_init(void)
>          pv_ops.time.steal_clock = kvm_steal_clock;
>      }
> 
> -    if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
> -        !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
> -        kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
> +    if (pv_tlb_flush_supported()) {
>          pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
>          pv_ops.mmu.tlb_remove_table = tlb_remove_table;
>      }
> @@ -632,9 +650,7 @@ static void __init kvm_guest_init(void)
>  #ifdef CONFIG_SMP
>      smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus;
>      smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
> -    if (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
> -        !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
> -        kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
> +    if (pv_sched_yield_supported()) {
>          smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
>          pr_info("KVM setup pv sched yield\n");
>      }
> @@ -700,7 +716,7 @@ static uint32_t __init kvm_detect(void)
>  static void __init kvm_apic_init(void)
>  {
>  #if defined(CONFIG_SMP)
> -    if (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI))
> +    if (pv_ipi_supported())
>          kvm_setup_pv_ipi();
>  #endif
>  }
> @@ -739,9 +755,7 @@ static __init int kvm_setup_pv_tlb_flush(void)
>      if (!kvm_para_available() || nopv)
>          return 0;
> 
> -    if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
> -        !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
> -        kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
> +    if (pv_tlb_flush_supported()) {
>          for_each_possible_cpu(cpu) {
>              zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu),
>                  GFP_KERNEL, cpu_to_node(cpu));
> --
> 2.7.4