KVM: s390: Wire up ioeventfd.

Enable ioeventfd support on s390 and hook up diagnose 500 virtio-ccw
notifications.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

4 files changed, 29 insertions, 1 deletions

diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
index 60f9f8ae0fc8..70b46eacf8e1 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 3975722bb19d..8fe9d65a4585 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 a390687feb13..1c01a9912989 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 < 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 6cae4ad647a9..33161b4a8280 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: