1 files changed, 510 insertions, 0 deletions
diff --git a/drivers/s390/virtio/kvm_virtio.c b/drivers/s390/virtio/kvm_virtio.c
new file mode 100644
index 000000000000..dd65c8b4c7fe
--- /dev/null
+++ b/drivers/s390/virtio/kvm_virtio.c
@@ -0,0 +1,510 @@
+/*
+ * virtio for kvm on s390
+ *
+ * Copyright IBM Corp. 2008
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ *
+ *    Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
+ */
+
+#include <linux/kernel_stat.h>
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/err.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/slab.h>
+#include <linux/virtio_console.h>
+#include <linux/interrupt.h>
+#include <linux/virtio_ring.h>
+#include <linux/export.h>
+#include <linux/pfn.h>
+#include <asm/io.h>
+#include <asm/kvm_para.h>
+#include <asm/kvm_virtio.h>
+#include <asm/sclp.h>
+#include <asm/setup.h>
+#include <asm/irq.h>
+
+#define VIRTIO_SUBCODE_64 0x0D00
+
+/*
+ * The pointer to our (page) of device descriptions.
+ */
+static void *kvm_devices;
+static struct work_struct hotplug_work;
+
+struct kvm_device {
+	struct virtio_device vdev;
+	struct kvm_device_desc *desc;
+};
+
+#define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev)
+
+/*
+ * memory layout:
+ * - kvm_device_descriptor
+ *        struct kvm_device_desc
+ * - configuration
+ *        struct kvm_vqconfig
+ * - feature bits
+ * - config space
+ */
+static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc)
+{
+	return (struct kvm_vqconfig *)(desc + 1);
+}
+
+static u8 *kvm_vq_features(const struct kvm_device_desc *desc)
+{
+	return (u8 *)(kvm_vq_config(desc) + desc->num_vq);
+}
+
+static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc)
+{
+	return kvm_vq_features(desc) + desc->feature_len * 2;
+}
+
+/*
+ * The total size of the config page used by this device (incl. desc)
+ */
+static unsigned desc_size(const struct kvm_device_desc *desc)
+{
+	return sizeof(*desc)
+		+ desc->num_vq * sizeof(struct kvm_vqconfig)
+		+ desc->feature_len * 2
+		+ desc->config_len;
+}
+
+/* This gets the device's feature bits. */
+static u64 kvm_get_features(struct virtio_device *vdev)
+{
+	unsigned int i;
+	u32 features = 0;
+	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
+	u8 *in_features = kvm_vq_features(desc);
+
+	for (i = 0; i < min(desc->feature_len * 8, 32); i++)
+		if (in_features[i / 8] & (1 << (i % 8)))
+			features |= (1 << i);
+	return features;
+}
+
+static int kvm_finalize_features(struct virtio_device *vdev)
+{
+	unsigned int i, bits;
+	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
+	/* Second half of bitmap is features we accept. */
+	u8 *out_features = kvm_vq_features(desc) + desc->feature_len;
+
+	/* Give virtio_ring a chance to accept features. */
+	vring_transport_features(vdev);
+
+	/* Make sure we don't have any features > 32 bits! */
+	BUG_ON((u32)vdev->features != vdev->features);
+
+	memset(out_features, 0, desc->feature_len);
+	bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
+	for (i = 0; i < bits; i++) {
+		if (__virtio_test_bit(vdev, i))
+			out_features[i / 8] |= (1 << (i % 8));
+	}
+
+	return 0;
+}
+
+/*
+ * Reading and writing elements in config space
+ */
+static void kvm_get(struct virtio_device *vdev, unsigned int offset,
+		   void *buf, unsigned len)
+{
+	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
+
+	BUG_ON(offset + len > desc->config_len);
+	memcpy(buf, kvm_vq_configspace(desc) + offset, len);
+}
+
+static void kvm_set(struct virtio_device *vdev, unsigned int offset,
+		   const void *buf, unsigned len)
+{
+	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
+
+	BUG_ON(offset + len > desc->config_len);
+	memcpy(kvm_vq_configspace(desc) + offset, buf, len);
+}
+
+/*
+ * The operations to get and set the status word just access
+ * the status field of the device descriptor. set_status will also
+ * make a hypercall to the host, to tell about status changes
+ */
+static u8 kvm_get_status(struct virtio_device *vdev)
+{
+	return to_kvmdev(vdev)->desc->status;
+}
+
+static void kvm_set_status(struct virtio_device *vdev, u8 status)
+{
+	BUG_ON(!status);
+	to_kvmdev(vdev)->desc->status = status;
+	kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS,
+		       (unsigned long) to_kvmdev(vdev)->desc);
+}
+
+/*
+ * To reset the device, we use the KVM_VIRTIO_RESET hypercall, using the
+ * descriptor address. The Host will zero the status and all the
+ * features.
+ */
+static void kvm_reset(struct virtio_device *vdev)
+{
+	kvm_hypercall1(KVM_S390_VIRTIO_RESET,
+		       (unsigned long) to_kvmdev(vdev)->desc);
+}
+
+/*
+ * When the virtio_ring code wants to notify the Host, it calls us here and we
+ * make a hypercall.  We hand the address  of the virtqueue so the Host
+ * knows which virtqueue we're talking about.
+ */
+static bool kvm_notify(struct virtqueue *vq)
+{
+	long rc;
+	struct kvm_vqconfig *config = vq->priv;
+
+	rc = kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
+	if (rc < 0)
+		return false;
+	return true;
+}
+
+/*
+ * This routine finds the first virtqueue described in the configuration of
+ * this device and sets it up.
+ */
+static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
+				     unsigned index,
+				     void (*callback)(struct virtqueue *vq),
+				     const char *name)
+{
+	struct kvm_device *kdev = to_kvmdev(vdev);
+	struct kvm_vqconfig *config;
+	struct virtqueue *vq;
+	int err;
+
+	if (index >= kdev->desc->num_vq)
+		return ERR_PTR(-ENOENT);
+
+	if (!name)
+		return NULL;
+
+	config = kvm_vq_config(kdev->desc)+index;
+
+	err = vmem_add_mapping(config->address,
+			       vring_size(config->num,
+					  KVM_S390_VIRTIO_RING_ALIGN));
+	if (err)
+		goto out;
+
+	vq = vring_new_virtqueue(index, config->num, KVM_S390_VIRTIO_RING_ALIGN,
+				 vdev, true, (void *) config->address,
+				 kvm_notify, callback, name);
+	if (!vq) {
+		err = -ENOMEM;
+		goto unmap;
+	}
+
+	/*
+	 * register a callback token
+	 * The host will sent this via the external interrupt parameter
+	 */
+	config->token = (u64) vq;
+
+	vq->priv = config;
+	return vq;
+unmap:
+	vmem_remove_mapping(config->address,
+			    vring_size(config->num,
+				       KVM_S390_VIRTIO_RING_ALIGN));
+out:
+	return ERR_PTR(err);
+}
+
+static void kvm_del_vq(struct virtqueue *vq)
+{
+	struct kvm_vqconfig *config = vq->priv;
+
+	vring_del_virtqueue(vq);
+	vmem_remove_mapping(config->address,
+			    vring_size(config->num,
+				       KVM_S390_VIRTIO_RING_ALIGN));
+}
+
+static void kvm_del_vqs(struct virtio_device *vdev)
+{
+	struct virtqueue *vq, *n;
+
+	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+		kvm_del_vq(vq);
+}
+
+static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+			struct virtqueue *vqs[],
+			vq_callback_t *callbacks[],
+			const char *names[])
+{
+	struct kvm_device *kdev = to_kvmdev(vdev);
+	int i;
+
+	/* We must have this many virtqueues. */
+	if (nvqs > kdev->desc->num_vq)
+		return -ENOENT;
+
+	for (i = 0; i < nvqs; ++i) {
+		vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i]);
+		if (IS_ERR(vqs[i]))
+			goto error;
+	}
+	return 0;
+
+error:
+	kvm_del_vqs(vdev);
+	return PTR_ERR(vqs[i]);
+}
+
+static const char *kvm_bus_name(struct virtio_device *vdev)
+{
+	return "";
+}
+
+/*
+ * The config ops structure as defined by virtio config
+ */
+static const struct virtio_config_ops kvm_vq_configspace_ops = {
+	.get_features = kvm_get_features,
+	.finalize_features = kvm_finalize_features,
+	.get = kvm_get,
+	.set = kvm_set,
+	.get_status = kvm_get_status,
+	.set_status = kvm_set_status,
+	.reset = kvm_reset,
+	.find_vqs = kvm_find_vqs,
+	.del_vqs = kvm_del_vqs,
+	.bus_name = kvm_bus_name,
+};
+
+/*
+ * The root device for the kvm virtio devices.
+ * This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2.
+ */
+static struct device *kvm_root;
+
+/*
+ * adds a new device and register it with virtio
+ * appropriate drivers are loaded by the device model
+ */
+static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
+{
+	struct kvm_device *kdev;
+
+	kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
+	if (!kdev) {
+		printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
+		       offset, d->type);
+		return;
+	}
+
+	kdev->vdev.dev.parent = kvm_root;
+	kdev->vdev.id.device = d->type;
+	kdev->vdev.config = &kvm_vq_configspace_ops;
+	kdev->desc = d;
+
+	if (register_virtio_device(&kdev->vdev) != 0) {
+		printk(KERN_ERR "Failed to register kvm device %u type %u\n",
+		       offset, d->type);
+		kfree(kdev);
+	}
+}
+
+/*
+ * scan_devices() simply iterates through the device page.
+ * The type 0 is reserved to mean "end of devices".
+ */
+static void scan_devices(void)
+{
+	unsigned int i;
+	struct kvm_device_desc *d;
+
+	for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
+		d = kvm_devices + i;
+
+		if (d->type == 0)
+			break;
+
+		add_kvm_device(d, i);
+	}
+}
+
+/*
+ * match for a kvm device with a specific desc pointer
+ */
+static int match_desc(struct device *dev, void *data)
+{
+	struct virtio_device *vdev = dev_to_virtio(dev);
+	struct kvm_device *kdev = to_kvmdev(vdev);
+
+	return kdev->desc == data;
+}
+
+/*
+ * hotplug_device tries to find changes in the device page.
+ */
+static void hotplug_devices(struct work_struct *dummy)
+{
+	unsigned int i;
+	struct kvm_device_desc *d;
+	struct device *dev;
+
+	for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
+		d = kvm_devices + i;
+
+		/* end of list */
+		if (d->type == 0)
+			break;
+
+		/* device already exists */
+		dev = device_find_child(kvm_root, d, match_desc);
+		if (dev) {
+			/* XXX check for hotplug remove */
+			put_device(dev);
+			continue;
+		}
+
+		/* new device */
+		printk(KERN_INFO "Adding new virtio device %p\n", d);
+		add_kvm_device(d, i);
+	}
+}
+
+/*
+ * we emulate the request_irq behaviour on top of s390 extints
+ */
+static void kvm_extint_handler(struct ext_code ext_code,
+			       unsigned int param32, unsigned long param64)
+{
+	struct virtqueue *vq;
+	u32 param;
+
+	if ((ext_code.subcode & 0xff00) != VIRTIO_SUBCODE_64)
+		return;
+	inc_irq_stat(IRQEXT_VRT);
+
+	/* The LSB might be overloaded, we have to mask it */
+	vq = (struct virtqueue *)(param64 & ~1UL);
+
+	/* We use ext_params to decide what this interrupt means */
+	param = param32 & VIRTIO_PARAM_MASK;
+
+	switch (param) {
+	case VIRTIO_PARAM_CONFIG_CHANGED:
+		virtio_config_changed(vq->vdev);
+		break;
+	case VIRTIO_PARAM_DEV_ADD:
+		schedule_work(&hotplug_work);
+		break;
+	case VIRTIO_PARAM_VRING_INTERRUPT:
+	default:
+		vring_interrupt(0, vq);
+		break;
+	}
+}
+
+/*
+ * For s390-virtio, we expect a page above main storage containing
+ * the virtio configuration. Try to actually load from this area
+ * in order to figure out if the host provides this page.
+ */
+static int __init test_devices_support(unsigned long addr)
+{
+	int ret = -EIO;
+
+	asm volatile(
+		"0:	lura	0,%1\n"
+		"1:	xgr	%0,%0\n"
+		"2:\n"
+		EX_TABLE(0b,2b)
+		EX_TABLE(1b,2b)
+		: "+d" (ret)
+		: "a" (addr)
+		: "0", "cc");
+	return ret;
+}
+/*
+ * Init function for virtio
+ * devices are in a single page above top of "normal" + standby mem
+ */
+static int __init kvm_devices_init(void)
+{
+	int rc;
+	unsigned long total_memory_size = sclp_get_rzm() * sclp_get_rnmax();
+
+	if (!MACHINE_IS_KVM)
+		return -ENODEV;
+
+	if (test_devices_support(total_memory_size) < 0)
+		return -ENODEV;
+
+	rc = vmem_add_mapping(total_memory_size, PAGE_SIZE);
+	if (rc)
+		return rc;
+
+	kvm_devices = (void *) total_memory_size;
+
+	kvm_root = root_device_register("kvm_s390");
+	if (IS_ERR(kvm_root)) {
+		rc = PTR_ERR(kvm_root);
+		printk(KERN_ERR "Could not register kvm_s390 root device");
+		vmem_remove_mapping(total_memory_size, PAGE_SIZE);
+		return rc;
+	}
+
+	INIT_WORK(&hotplug_work, hotplug_devices);
+
+	irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
+	register_external_irq(EXT_IRQ_CP_SERVICE, kvm_extint_handler);
+
+	scan_devices();
+	return 0;
+}
+
+/* code for early console output with virtio_console */
+static __init int early_put_chars(u32 vtermno, const char *buf, int count)
+{
+	char scratch[17];
+	unsigned int len = count;
+
+	if (len > sizeof(scratch) - 1)
+		len = sizeof(scratch) - 1;
+	scratch[len] = '\0';
+	memcpy(scratch, buf, len);
+	kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
+	return len;
+}
+
+static int __init s390_virtio_console_init(void)
+{
+	if (sclp_has_vt220() || sclp_has_linemode())
+		return -ENODEV;
+	return virtio_cons_early_init(early_put_chars);
+}
+console_initcall(s390_virtio_console_init);
+
+
+/*
+ * We do this after core stuff, but before the drivers.
+ */
+postcore_initcall(kvm_devices_init);