Re: [Qemu-devel] [RFC PATCH v2 4/4] KVM: s390: Wire up ioeventfd.

[Michael S. Tsirkin]

On Fri, Feb 22, 2013 at 01:09:49PM +0100, Cornelia Huck wrote:
> Enable ioeventfd support on s390 and hook up diagnose 500 virtio-ccw
> notifications.
> 
> Signed-off-by: Cornelia Huck <address@hidden>
> ---
>  arch/s390/kvm/Kconfig    |  1 +
>  arch/s390/kvm/Makefile   |  2 +-
>  arch/s390/kvm/diag.c     | 25 +++++++++++++++++++++++++
>  arch/s390/kvm/kvm-s390.c |  1 +
>  4 files changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
> index b58dd86..3c43e30 100644
> --- a/arch/s390/kvm/Kconfig
> +++ b/arch/s390/kvm/Kconfig
> @@ -22,6 +22,7 @@ config KVM
>       select PREEMPT_NOTIFIERS
>       select ANON_INODES
>       select HAVE_KVM_CPU_RELAX_INTERCEPT
> +     select HAVE_KVM_EVENTFD
>       ---help---
>         Support hosting paravirtualized guest machines using the SIE
>         virtualization capability on the mainframe. This should work
> diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile
> index 3975722..8fe9d65 100644
> --- a/arch/s390/kvm/Makefile
> +++ b/arch/s390/kvm/Makefile
> @@ -6,7 +6,7 @@
>  # it under the terms of the GNU General Public License (version 2 only)
>  # as published by the Free Software Foundation.
>  
> -common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o)
> +common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o eventfd.o)
>  
>  ccflags-y := -Ivirt/kvm -Iarch/s390/kvm
>  
> diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
> index a390687..13cf74a 100644
> --- a/arch/s390/kvm/diag.c
> +++ b/arch/s390/kvm/diag.c
> @@ -104,6 +104,29 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
>       return -EREMOTE;
>  }
>  
> +static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
> +{
> +     int ret, idx;
> +
> +     /* No virtio-ccw notification? Get out quickly. */
> +     if (!vcpu->kvm->arch.css_support ||
> +         (vcpu->run->s.regs.gprs[1] != 3))
> +             return -EOPNOTSUPP;

Looks like we have:
arch/s390/include/uapi/asm/kvm_virtio.h:#define KVM_S390_VIRTIO_NOTIFY 0
arch/s390/include/uapi/asm/kvm_virtio.h:#define KVM_S390_VIRTIO_RESET 1
arch/s390/include/uapi/asm/kvm_virtio.h:#define KVM_S390_VIRTIO_SET_STATUS      
2

KVM_S390_VIRTIO_CSS_NOTIFY is missing? Strange.
Maybe it should be added in that header and included here?
Do some guests use it?
Also, do you want to support KVM_S390_VIRTIO_NOTIFY as well?


> +
> +     idx = srcu_read_lock(&vcpu->kvm->srcu);
> +     /*
> +      * The layout is as follows:
> +      * - gpr 2 contains the subchannel id (passed as addr)
> +      * - gpr 3 contains the virtqueue index (passed as datamatch)
> +      */
> +     ret = kvm_io_bus_write(vcpu->kvm, KVM_CSS_BUS,
> +                             vcpu->run->s.regs.gprs[2],
> +                             8, &vcpu->run->s.regs.gprs[3]);
> +     srcu_read_unlock(&vcpu->kvm->srcu, idx);
> +     /* kvm_io_bus_write returns -EOPNOTSUPP if it found no match. */
> +     return ret;
> +}
> +
>  int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
>  {
>       int code = (vcpu->arch.sie_block->ipb & 0xfff0000) >> 16;
> @@ -118,6 +141,8 @@ int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
>               return __diag_time_slice_end_directed(vcpu);
>       case 0x308:
>               return __diag_ipl_functions(vcpu);
> +     case 0x500:
> +             return __diag_virtio_hypercall(vcpu);
>       default:
>               return -EOPNOTSUPP;
>       }
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index f822d36..04d2454 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -142,6 +142,7 @@ int kvm_dev_ioctl_check_extension(long ext)
>       case KVM_CAP_ONE_REG:
>       case KVM_CAP_ENABLE_CAP:
>       case KVM_CAP_S390_CSS_SUPPORT:
> +     case KVM_CAP_IOEVENTFD:
>               r = 1;
>               break;
>       case KVM_CAP_NR_VCPUS:
> -- 
> 1.7.12.4