Re: [Qemu-devel] [PATCH v2 5/5] kvm/x86: Hyper-V VMBus hypercall userspace exit

[Paolo Bonzini]

On 21/01/2016 15:01, Andrey Smetanin wrote:
> The patch implements KVM_EXIT_HYPERV userspace exit
> functionality for Hyper-V VMBus hypercalls:
> HV_X64_HCALL_POST_MESSAGE, HV_X64_HCALL_SIGNAL_EVENT.
> 
> Changes v2:
> * use KVM_EXIT_HYPERV for hypercalls
> 
> Signed-off-by: Andrey Smetanin <address@hidden>
> Reviewed-by: Roman Kagan <address@hidden>
> CC: Gleb Natapov <address@hidden>
> CC: Paolo Bonzini <address@hidden>
> CC: Joerg Roedel <address@hidden>
> CC: "K. Y. Srinivasan" <address@hidden>
> CC: Haiyang Zhang <address@hidden>
> CC: Roman Kagan <address@hidden>
> CC: Denis V. Lunev <address@hidden>
> CC: address@hidden
> ---
>  Documentation/virtual/kvm/api.txt |  6 ++++++
>  arch/x86/kvm/hyperv.c             | 29 ++++++++++++++++++++++-------
>  arch/x86/kvm/hyperv.h             |  1 +
>  arch/x86/kvm/x86.c                |  5 +++++
>  include/uapi/linux/kvm.h          |  6 ++++++
>  5 files changed, 40 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/virtual/kvm/api.txt 
> b/Documentation/virtual/kvm/api.txt
> index 053f613..1bf1a07 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -3339,6 +3339,7 @@ EOI was received.
>  
>               struct kvm_hyperv_exit {
>  #define KVM_EXIT_HYPERV_SYNIC          1
> +#define KVM_EXIT_HYPERV_HCALL          2
>                       __u32 type;
>                       union {
>                               struct {
> @@ -3347,6 +3348,11 @@ EOI was received.
>                                       __u64 evt_page;
>                                       __u64 msg_page;
>                               } synic;
> +                             struct {
> +                                     __u64 input;
> +                                     __u64 result;
> +                                     __u64 params[2];
> +                             } hcall;
>                       } u;
>               };
>               /* KVM_EXIT_HYPERV */
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index e1daa8b..26ae973 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -1093,6 +1093,14 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>       case HV_X64_HCALL_NOTIFY_LONG_SPIN_WAIT:
>               kvm_vcpu_on_spin(vcpu);
>               break;
> +     case HV_X64_HCALL_POST_MESSAGE:
> +     case HV_X64_HCALL_SIGNAL_EVENT:
> +             vcpu->run->exit_reason = KVM_EXIT_HYPERV;
> +             vcpu->run->hyperv.type = KVM_EXIT_HYPERV_HCALL;
> +             vcpu->run->hyperv.u.hcall.input = param;
> +             vcpu->run->hyperv.u.hcall.params[0] = ingpa;
> +             vcpu->run->hyperv.u.hcall.params[1] = outgpa;
> +             return 0;
>       default:
>               res = HV_STATUS_INVALID_HYPERCALL_CODE;
>               break;
> @@ -1100,12 +1108,19 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>  
>  set_result:
>       ret = res | (((u64)rep_done & 0xfff) << 32);
> -     if (longmode) {
> -             kvm_register_write(vcpu, VCPU_REGS_RAX, ret);
> -     } else {
> -             kvm_register_write(vcpu, VCPU_REGS_RDX, ret >> 32);
> -             kvm_register_write(vcpu, VCPU_REGS_RAX, ret & 0xffffffff);
> -     }
> -
> +     kvm_hv_hypercall_set_result(vcpu, ret);
>       return 1;
>  }
> +
> +void kvm_hv_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result)
> +{
> +     bool longmode;
> +
> +     longmode = is_64_bit_mode(vcpu);
> +     if (longmode)
> +             kvm_register_write(vcpu, VCPU_REGS_RAX, result);
> +     else {
> +             kvm_register_write(vcpu, VCPU_REGS_RDX, result >> 32);
> +             kvm_register_write(vcpu, VCPU_REGS_RAX, result & 0xffffffff);
> +     }
> +}
> diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
> index 60eccd4..64a4a3b 100644
> --- a/arch/x86/kvm/hyperv.h
> +++ b/arch/x86/kvm/hyperv.h
> @@ -52,6 +52,7 @@ int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, 
> u64 *pdata);
>  
>  bool kvm_hv_hypercall_enabled(struct kvm *kvm);
>  int kvm_hv_hypercall(struct kvm_vcpu *vcpu);
> +void kvm_hv_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result);
>  
>  void kvm_hv_irq_routing_update(struct kvm *kvm);
>  int kvm_hv_synic_set_irq(struct kvm *kvm, u32 vcpu_id, u32 sint);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index f53f5b1..e5c842b 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6891,6 +6891,11 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, 
> struct kvm_run *kvm_run)
>       } else
>               WARN_ON(vcpu->arch.pio.count || vcpu->mmio_needed);
>  
> +     if (unlikely(kvm_run->exit_reason == KVM_EXIT_HYPERV) &&
> +         kvm_run->hyperv.type == KVM_EXIT_HYPERV_HCALL)
> +             kvm_hv_hypercall_set_result(vcpu,
> +                                         kvm_run->hyperv.u.hcall.result);

Can you use vcpu->arch.complete_userspace_io here instead?

Otherwise looks great, thanks.

Paolo

> +
>       r = vcpu_run(vcpu);
>  
>  out:
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 9da9051..c5519a9 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -157,6 +157,7 @@ struct kvm_s390_skeys {
>  
>  struct kvm_hyperv_exit {
>  #define KVM_EXIT_HYPERV_SYNIC          1
> +#define KVM_EXIT_HYPERV_HCALL          2
>       __u32 type;
>       union {
>               struct {
> @@ -165,6 +166,11 @@ struct kvm_hyperv_exit {
>                       __u64 evt_page;
>                       __u64 msg_page;
>               } synic;
> +             struct {
> +                     __u64 input;
> +                     __u64 result;
> +                     __u64 params[2];
> +             } hcall;
>       } u;
>  };
>  
>