Re: [Qemu-devel] [PATCH v4 6/6] KVM: s390: Wire up ioeventfd.

[Michael S. Tsirkin]

On Thu, Feb 28, 2013 at 10:22:32AM +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     | 26 ++++++++++++++++++++++++++
>  arch/s390/kvm/kvm-s390.c |  1 +
>  4 files changed, 29 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..96907f2 100644
> --- a/arch/s390/kvm/diag.c
> +++ b/arch/s390/kvm/diag.c
> @@ -13,6 +13,7 @@
>  
>  #include <linux/kvm.h>
>  #include <linux/kvm_host.h>
> +#include <asm/virtio-ccw.h>
>  #include "kvm-s390.h"
>  #include "trace.h"
>  #include "trace-s390.h"
> @@ -104,6 +105,29 @@ 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] != KVM_S390_VIRTIO_CCW_NOTIFY))
> +             return -EOPNOTSUPP;
> +
> +     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_VIRTIO_CCW_NOTIFY_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;

Yes but it returns 8 on success. You probably want 0. So:
        return ret < 0 ? ret : 0;

> +}
> +
>  int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
>  {
>       int code = (vcpu->arch.sie_block->ipb & 0xfff0000) >> 16;
> @@ -118,6 +142,8 @@ 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