--- /dev/null
+/*
+ * kvm_virtio.c - 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/init.h>
+#include <linux/bootmem.h>
+#include <linux/err.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/interrupt.h>
+#include <linux/virtio_ring.h>
+#include <asm/io.h>
+#include <asm/kvm_para.h>
+#include <asm/kvm_virtio.h>
+#include <asm/setup.h>
+#include <asm/s390_ext.h>
+
+#define VIRTIO_SUBCODE_64 0x0D00
+
+/*
+ * The pointer to our (page) of device descriptions.
+ */
+static void *kvm_devices;
+
+/*
+ * Unique numbering for kvm devices.
+ */
+static unsigned int dev_index;
+
+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 tests (and acknowleges) a feature bit.
+ */
+static bool kvm_feature(struct virtio_device *vdev, unsigned fbit)
+{
+ struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
+ u8 *features;
+
+ if (fbit / 8 > desc->feature_len)
+ return false;
+
+ features = kvm_vq_features(desc);
+ if (!(features[fbit / 8] & (1 << (fbit % 8))))
+ return false;
+
+ /*
+ * We set the matching bit in the other half of the bitmap to tell the
+ * Host we want to use this feature.
+ */
+ features[desc->feature_len + fbit / 8] |= (1 << (fbit % 8));
+ return true;
+}
+
+/*
+ * 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 void kvm_notify(struct virtqueue *vq)
+{
+ struct kvm_vqconfig *config = vq->priv;
+
+ kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
+}
+
+/*
+ * 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))
+{
+ 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);
+
+ config = kvm_vq_config(kdev->desc)+index;
+
+ if (add_shared_memory(config->address,
+ vring_size(config->num, PAGE_SIZE))) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ vq = vring_new_virtqueue(config->num, vdev, (void *) config->address,
+ kvm_notify, callback);
+ 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:
+ remove_shared_memory(config->address, vring_size(config->num,
+ PAGE_SIZE));
+out:
+ return ERR_PTR(err);
+}
+
+static void kvm_del_vq(struct virtqueue *vq)
+{
+ struct kvm_vqconfig *config = vq->priv;
+
+ vring_del_virtqueue(vq);
+ remove_shared_memory(config->address,
+ vring_size(config->num, PAGE_SIZE));
+}
+
+/*
+ * The config ops structure as defined by virtio config
+ */
+static struct virtio_config_ops kvm_vq_configspace_ops = {
+ .feature = kvm_feature,
+ .get = kvm_get,
+ .set = kvm_set,
+ .get_status = kvm_get_status,
+ .set_status = kvm_set_status,
+ .reset = kvm_reset,
+ .find_vq = kvm_find_vq,
+ .del_vq = kvm_del_vq,
+};
+
+/*
+ * 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 = {
+ .parent = NULL,
+ .bus_id = "kvm_s390",
+};
+
+/*
+ * 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)
+{
+ struct kvm_device *kdev;
+
+ kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
+ if (!kdev) {
+ printk(KERN_EMERG "Cannot allocate kvm dev %u\n",
+ dev_index++);
+ return;
+ }
+
+ kdev->vdev.dev.parent = &kvm_root;
+ kdev->vdev.index = dev_index++;
+ 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\n",
+ kdev->vdev.index);
+ 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);
+ }
+}
+
+/*
+ * we emulate the request_irq behaviour on top of s390 extints
+ */
+static void kvm_extint_handler(u16 code)
+{
+ void *data = (void *) *(long *) __LC_PFAULT_INTPARM;
+ u16 subcode = S390_lowcore.cpu_addr;
+
+ if ((subcode & 0xff00) != VIRTIO_SUBCODE_64)
+ return;
+
+ vring_interrupt(0, data);
+}
+
+/*
+ * Init function for virtio
+ * devices are in a single page above top of "normal" mem
+ */
+static int __init kvm_devices_init(void)
+{
+ int rc;
+
+ if (!MACHINE_IS_KVM)
+ return -ENODEV;
+
+ rc = device_register(&kvm_root);
+ if (rc) {
+ printk(KERN_ERR "Could not register kvm_s390 root device");
+ return rc;
+ }
+
+ if (add_shared_memory((max_pfn) << PAGE_SHIFT, PAGE_SIZE)) {
+ device_unregister(&kvm_root);
+ return -ENOMEM;
+ }
+
+ kvm_devices = (void *) (max_pfn << PAGE_SHIFT);
+
+ ctl_set_bit(0, 9);
+ register_external_interrupt(0x2603, kvm_extint_handler);
+
+ scan_devices();
+ return 0;
+}
+
+/*
+ * We do this after core stuff, but before the drivers.
+ */
+postcore_initcall(kvm_devices_init);
#define __S390_KVM_PARA_H
/*
- * No hypercalls for KVM on s390
+ * Hypercalls for KVM on s390. The calling convention is similar to the
+ * s390 ABI, so we use R2-R6 for parameters 1-5. In addition we use R1
+ * as hypercall number and R7 as parameter 6. The return value is
+ * written to R2. We use the diagnose instruction as hypercall. To avoid
+ * conflicts with existing diagnoses for LPAR and z/VM, we do not use
+ * the instruction encoded number, but specify the number in R1 and
+ * use 0x500 as KVM hypercall
+ *
+ * Copyright IBM Corp. 2007,2008
+ * Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
*/
+static inline long kvm_hypercall0(unsigned long nr)
+{
+ register unsigned long __nr asm("1") = nr;
+ register long __rc asm("2");
+
+ asm volatile ("diag 2,4,0x500\n"
+ : "=d" (__rc) : "d" (__nr): "memory", "cc");
+ return __rc;
+}
+
+static inline long kvm_hypercall1(unsigned long nr, unsigned long p1)
+{
+ register unsigned long __nr asm("1") = nr;
+ register unsigned long __p1 asm("2") = p1;
+ register long __rc asm("2");
+
+ asm volatile ("diag 2,4,0x500\n"
+ : "=d" (__rc) : "d" (__nr), "0" (__p1) : "memory", "cc");
+ return __rc;
+}
+
+static inline long kvm_hypercall2(unsigned long nr, unsigned long p1,
+ unsigned long p2)
+{
+ register unsigned long __nr asm("1") = nr;
+ register unsigned long __p1 asm("2") = p1;
+ register unsigned long __p2 asm("3") = p2;
+ register long __rc asm("2");
+
+ asm volatile ("diag 2,4,0x500\n"
+ : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2)
+ : "memory", "cc");
+ return __rc;
+}
+
+static inline long kvm_hypercall3(unsigned long nr, unsigned long p1,
+ unsigned long p2, unsigned long p3)
+{
+ register unsigned long __nr asm("1") = nr;
+ register unsigned long __p1 asm("2") = p1;
+ register unsigned long __p2 asm("3") = p2;
+ register unsigned long __p3 asm("4") = p3;
+ register long __rc asm("2");
+
+ asm volatile ("diag 2,4,0x500\n"
+ : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
+ "d" (__p3) : "memory", "cc");
+ return __rc;
+}
+
+
+static inline long kvm_hypercall4(unsigned long nr, unsigned long p1,
+ unsigned long p2, unsigned long p3,
+ unsigned long p4)
+{
+ register unsigned long __nr asm("1") = nr;
+ register unsigned long __p1 asm("2") = p1;
+ register unsigned long __p2 asm("3") = p2;
+ register unsigned long __p3 asm("4") = p3;
+ register unsigned long __p4 asm("5") = p4;
+ register long __rc asm("2");
+
+ asm volatile ("diag 2,4,0x500\n"
+ : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
+ "d" (__p3), "d" (__p4) : "memory", "cc");
+ return __rc;
+}
+
+static inline long kvm_hypercall5(unsigned long nr, unsigned long p1,
+ unsigned long p2, unsigned long p3,
+ unsigned long p4, unsigned long p5)
+{
+ register unsigned long __nr asm("1") = nr;
+ register unsigned long __p1 asm("2") = p1;
+ register unsigned long __p2 asm("3") = p2;
+ register unsigned long __p3 asm("4") = p3;
+ register unsigned long __p4 asm("5") = p4;
+ register unsigned long __p5 asm("6") = p5;
+ register long __rc asm("2");
+
+ asm volatile ("diag 2,4,0x500\n"
+ : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
+ "d" (__p3), "d" (__p4), "d" (__p5) : "memory", "cc");
+ return __rc;
+}
+
+static inline long kvm_hypercall6(unsigned long nr, unsigned long p1,
+ unsigned long p2, unsigned long p3,
+ unsigned long p4, unsigned long p5,
+ unsigned long p6)
+{
+ register unsigned long __nr asm("1") = nr;
+ register unsigned long __p1 asm("2") = p1;
+ register unsigned long __p2 asm("3") = p2;
+ register unsigned long __p3 asm("4") = p3;
+ register unsigned long __p4 asm("5") = p4;
+ register unsigned long __p5 asm("6") = p5;
+ register unsigned long __p6 asm("7") = p6;
+ register long __rc asm("2");
+
+ asm volatile ("diag 2,4,0x500\n"
+ : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
+ "d" (__p3), "d" (__p4), "d" (__p5), "d" (__p6)
+ : "memory", "cc");
+ return __rc;
+}
+
+/* kvm on s390 is always paravirtualization enabled */
static inline int kvm_para_available(void)
{
- return 0;
+ return 1;
}
+/* No feature bits are currently assigned for kvm on s390 */
static inline unsigned int kvm_arch_para_features(void)
{
return 0;
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