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

[Paolo Bonzini <pbonzini@redhat.com>]

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 <asmetanin@virtuozzo.com>
> Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
> CC: Gleb Natapov <gleb@kernel.org>
> CC: Paolo Bonzini <pbonzini@redhat.com>
> CC: Joerg Roedel <joro@8bytes.org>
> CC: "K. Y. Srinivasan" <kys@microsoft.com>
> CC: Haiyang Zhang <haiyangz@microsoft.com>
> CC: Roman Kagan <rkagan@virtuozzo.com>
> CC: Denis V. Lunev <den@openvz.org>
> CC: qemu-devel@nongnu.org
> ---
>  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;
>  };
>  
>