From be3c5832d51174ef7f21cefd6ad612dabdcb62fd Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Tue, 18 Nov 2008 22:44:13 +0100 Subject: [PATCH] kvm-s390: implement config_changed for virtio on s390 This patch implements config_changed for the s390 virtio transport. We use the least significant bit of the interrupt parameter field to decide, if this interrupt should call the virtio virtqueue callback or the config_changed callback. This method is compatible with old host and guest code. Old 64 bit guests will not check the bit and trigger a harmless additional vring_interrupt call. Old host code will never set this bit, this is also safe. This patch also takes care of a potential future 31 bit virtio transport for s390. On 31 bit _LC_PFAULT_INTPARM and __LC_EXT_PARAMS are identical. We exploit the alignment of the token and fold the change bit into the lsb of the token itself. Signed-off-by: Christian Borntraeger Signed-off-by: Rusty Russell --- drivers/s390/kvm/kvm_virtio.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c index 4e8354aa857..28c90b89f2b 100644 --- a/drivers/s390/kvm/kvm_virtio.c +++ b/drivers/s390/kvm/kvm_virtio.c @@ -299,13 +299,29 @@ static void scan_devices(void) */ static void kvm_extint_handler(u16 code) { - void *data = (void *) *(long *) __LC_PFAULT_INTPARM; - u16 subcode = S390_lowcore.cpu_addr; + struct virtqueue *vq; + u16 subcode; + int config_changed; + subcode = S390_lowcore.cpu_addr; if ((subcode & 0xff00) != VIRTIO_SUBCODE_64) return; - vring_interrupt(0, data); + /* The LSB might be overloaded, we have to mask it */ + vq = (struct virtqueue *) ((*(long *) __LC_PFAULT_INTPARM) & ~1UL); + + /* We use the LSB of extparam, to decide, if this interrupt is a config + * change or a "standard" interrupt */ + config_changed = (*(int *) __LC_EXT_PARAMS & 1); + + if (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 + vring_interrupt(0, vq); } /* -- 2.41.1