Re: [Qemu-devel] [PATCH v2 2/2] i386/kvm: add support for Hyper-V IPI send

[Paolo Bonzini <pbonzini@redhat.com>]

On 09/10/2018 15:08, Vitaly Kuznetsov wrote:
> Hyper-V PV IPI support is merged to KVM, enable the feature in Qemu. When
> enabled, this allows Windows guests to send IPIs to other vCPUs with a
> single hypercall even when there are >64 vCPUs in the request.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
> ---
>  target/i386/cpu.c          |  1 +
>  target/i386/cpu.h          |  1 +
>  target/i386/hyperv-proto.h |  1 +
>  target/i386/kvm.c          | 14 +++++++++++++-
>  4 files changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index c88876dfe3..32ea041c06 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -5564,6 +5564,7 @@ static Property x86_cpu_properties[] = {
>      DEFINE_PROP_BOOL("hv-frequencies", X86CPU, hyperv_frequencies, false),
>      DEFINE_PROP_BOOL("hv-reenlightenment", X86CPU, hyperv_reenlightenment, false),
>      DEFINE_PROP_BOOL("hv-tlbflush", X86CPU, hyperv_tlbflush, false),
> +    DEFINE_PROP_BOOL("hv-ipi", X86CPU, hyperv_ipi, false),
>      DEFINE_PROP_BOOL("check", X86CPU, check_cpuid, true),
>      DEFINE_PROP_BOOL("enforce", X86CPU, enforce_cpuid, false),
>      DEFINE_PROP_BOOL("kvm", X86CPU, expose_kvm, true),
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 730c06f80a..caa1544b2e 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -1382,6 +1382,7 @@ struct X86CPU {
>      bool hyperv_frequencies;
>      bool hyperv_reenlightenment;
>      bool hyperv_tlbflush;
> +    bool hyperv_ipi;
>      bool check_cpuid;
>      bool enforce_cpuid;
>      bool expose_kvm;
> diff --git a/target/i386/hyperv-proto.h b/target/i386/hyperv-proto.h
> index d6d5a79293..87f36d14e8 100644
> --- a/target/i386/hyperv-proto.h
> +++ b/target/i386/hyperv-proto.h
> @@ -58,6 +58,7 @@
>  #define HV_APIC_ACCESS_RECOMMENDED          (1u << 3)
>  #define HV_SYSTEM_RESET_RECOMMENDED         (1u << 4)
>  #define HV_RELAXED_TIMING_RECOMMENDED       (1u << 5)
> +#define HV_CLUSTER_IPI_RECOMMENDED          (1u << 10)
>  #define HV_EX_PROCESSOR_MASKS_RECOMMENDED   (1u << 11)
>  
>  /*
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index dc4047b02f..795aa52938 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -608,7 +608,8 @@ static bool hyperv_enabled(X86CPU *cpu)
>              cpu->hyperv_synic ||
>              cpu->hyperv_stimer ||
>              cpu->hyperv_reenlightenment ||
> -            cpu->hyperv_tlbflush);
> +            cpu->hyperv_tlbflush ||
> +            cpu->hyperv_ipi);
>  }
>  
>  static int kvm_arch_set_tsc_khz(CPUState *cs)
> @@ -888,6 +889,17 @@ int kvm_arch_init_vcpu(CPUState *cs)
>              c->eax |= HV_REMOTE_TLB_FLUSH_RECOMMENDED;
>              c->eax |= HV_EX_PROCESSOR_MASKS_RECOMMENDED;
>          }
> +        if (cpu->hyperv_ipi) {
> +            if (kvm_check_extension(cs->kvm_state,
> +                                    KVM_CAP_HYPERV_SEND_IPI) <= 0) {
> +                fprintf(stderr, "Hyper-V IPI send support "
> +                        "(requested by 'hv-ipi' cpu flag) "
> +                        " is not supported by kernel\n");
> +                return -ENOSYS;
> +            }
> +            c->eax |= HV_CLUSTER_IPI_RECOMMENDED;
> +            c->eax |= HV_EX_PROCESSOR_MASKS_RECOMMENDED;
> +        }
>  
>          c->ebx = cpu->hyperv_spinlock_attempts;
>  
> 

Queued patch 2, thanks.

Paolo