KVM: S390: take a full byte as ext_param indicator

Currenty the ext_param field only distinguishes between "config change" and
"vring interrupt". We can do a lot more with it though, so let's enable a
full byte of possible values and constants to #defines while at it.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/s390/include/asm/kvm_virtio.h b/arch/s390/include/asm/kvm_virtio.h
index acdfdff..3f5d100 100644 (file)
--- a/arch/s390/include/asm/kvm_virtio.h
+++ b/arch/s390/include/asm/kvm_virtio.h
@@ -54,4 +54,10 @@ struct kvm_vqconfig {
  * This is pagesize for historical reasons. */
 #define KVM_S390_VIRTIO_RING_ALIGN     4096
 
+
+/* These values are supposed to be in ext_params on an interrupt */
+#define VIRTIO_PARAM_MASK              0xff
+#define VIRTIO_PARAM_VRING_INTERRUPT   0x0
+#define VIRTIO_PARAM_CONFIG_CHANGED    0x1
+
 #endif

diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index 4e298bc..68cef4d 100644 (file)
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -334,7 +334,7 @@ static void kvm_extint_handler(u16 code)
 {
        struct virtqueue *vq;
        u16 subcode;
-       int config_changed;
+       u32 param;
 
        subcode = S390_lowcore.cpu_addr;
        if ((subcode & 0xff00) != VIRTIO_SUBCODE_64)
@@ -343,18 +343,25 @@ static void kvm_extint_handler(u16 code)
        /* The LSB might be overloaded, we have to mask it */
        vq = (struct virtqueue *)(S390_lowcore.ext_params2 & ~1UL);
 
-       /* We use the LSB of extparam, to decide, if this interrupt is a config
-        * change or a "standard" interrupt */
-       config_changed = S390_lowcore.ext_params & 1;
+       /* We use ext_params to decide what this interrupt means */
+       param = S390_lowcore.ext_params & VIRTIO_PARAM_MASK;
 
-       if (config_changed) {
+       switch (param) {
+       case VIRTIO_PARAM_CONFIG_CHANGED:
+       {
                struct virtio_driver *drv;
                drv = container_of(vq->vdev->dev.driver,
                                   struct virtio_driver, driver);
                if (drv->config_changed)
                        drv->config_changed(vq->vdev);
-       } else
+
+               break;
+       }
+       case VIRTIO_PARAM_VRING_INTERRUPT:
+       default:
                vring_interrupt(0, vq);
+               break;
+       }
 }
 
 /*