s390x/kvm: implement floating-interrupt controller device

This patch implements a floating-interrupt controller device (flic)
which interacts with the s390 flic kvm_device.

Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

2 files changed, 287 insertions, 0 deletions

diff --git a/hw/intc/Makefile.objs b/hw/intc/Makefile.objs
index 60eb936e0d..c8a2318d56 100644
--- a/hw/intc/Makefile.objs
+++ b/hw/intc/Makefile.objs
@@ -25,3 +25,4 @@ obj-$(CONFIG_SH4) += sh_intc.o
 obj-$(CONFIG_XICS) += xics.o
 obj-$(CONFIG_XICS_KVM) += xics_kvm.o
 obj-$(CONFIG_ALLWINNER_A10_PIC) += allwinner-a10-pic.o
+obj-$(CONFIG_S390_FLIC) += s390_flic.o
diff --git a/hw/intc/s390_flic.c b/hw/intc/s390_flic.c
new file mode 100644
index 0000000000..1a7876da78
--- /dev/null
+++ b/hw/intc/s390_flic.c
@@ -0,0 +1,286 @@
+/*
+ * QEMU S390x KVM floating interrupt controller (flic)
+ *
+ * Copyright 2014 IBM Corp.
+ * Author(s): Jens Freimann <jfrei@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+
+#include <sys/ioctl.h>
+#include "qemu/error-report.h"
+#include "hw/sysbus.h"
+#include "sysemu/kvm.h"
+#include "migration/qemu-file.h"
+#include "hw/s390x/s390_flic.h"
+#include "trace.h"
+
+#define FLIC_SAVE_INITIAL_SIZE getpagesize()
+#define FLIC_FAILED (-1UL)
+#define FLIC_SAVEVM_VERSION 1
+
+void s390_flic_init(void)
+{
+    DeviceState *dev;
+    int r;
+
+    if (kvm_enabled()) {
+        dev = qdev_create(NULL, "s390-flic");
+        object_property_add_child(qdev_get_machine(), "s390-flic",
+                                OBJECT(dev), NULL);
+        r = qdev_init(dev);
+        if (r) {
+            error_report("flic: couldn't create qdev");
+        }
+    }
+}
+
+/**
+ * flic_get_all_irqs - store all pending irqs in buffer
+ * @buf: pointer to buffer which is passed to kernel
+ * @len: length of buffer
+ * @flic: pointer to flic device state
+ *
+ * Returns: -ENOMEM if buffer is too small,
+ * -EINVAL if attr.group is invalid,
+ * -EFAULT if copying to userspace failed,
+ * on success return number of stored interrupts
+ */
+static int flic_get_all_irqs(KVMS390FLICState *flic,
+                             void *buf, int len)
+{
+    struct kvm_device_attr attr = {
+        .group = KVM_DEV_FLIC_GET_ALL_IRQS,
+        .addr = (uint64_t) buf,
+        .attr = len,
+    };
+    int rc;
+
+    rc = ioctl(flic->fd, KVM_GET_DEVICE_ATTR, &attr);
+
+    return rc == -1 ? -errno : rc;
+}
+
+/** flic_enqueue_irqs - returns 0 on success
+ * @buf: pointer to buffer which is passed to kernel
+ * @len: length of buffer
+ * @flic: pointer to flic device state
+ *
+ * Returns: -EINVAL if attr.group is unknown
+ */
+static int flic_enqueue_irqs(void *buf, uint64_t len,
+                            KVMS390FLICState *flic)
+{
+    int rc;
+    struct kvm_device_attr attr = {
+        .group = KVM_DEV_FLIC_ENQUEUE,
+        .addr = (uint64_t) buf,
+        .attr = len,
+    };
+
+    rc = ioctl(flic->fd, KVM_SET_DEVICE_ATTR, &attr);
+
+    return rc ? -errno : 0;
+}
+
+/**
+ * __get_all_irqs - store all pending irqs in buffer
+ * @flic: pointer to flic device state
+ * @buf: pointer to pointer to a buffer
+ * @len: length of buffer
+ *
+ * Returns: return value of flic_get_all_irqs
+ * Note: Retry and increase buffer size until flic_get_all_irqs
+ * either returns a value >= 0 or a negative error code.
+ * -ENOMEM is an exception, which means the buffer is too small
+ * and we should try again. Other negative error codes can be
+ * -EFAULT and -EINVAL which we ignore at this point
+ */
+static int __get_all_irqs(KVMS390FLICState *flic,
+                          void **buf, int len)
+{
+    int r;
+
+    do {
+        /* returns -ENOMEM if buffer is too small and number
+         * of queued interrupts on success */
+        r = flic_get_all_irqs(flic, *buf, len);
+        if (r >= 0) {
+            break;
+        }
+        len *= 2;
+        *buf = g_try_realloc(*buf, len);
+        if (!buf) {
+            return -ENOMEM;
+        }
+    } while (r == -ENOMEM && len <= KVM_S390_FLIC_MAX_BUFFER);
+
+    return r;
+}
+
+/**
+ * kvm_flic_save - Save pending floating interrupts
+ * @f: QEMUFile containing migration state
+ * @opaque: pointer to flic device state
+ *
+ * Note: Pass buf and len to kernel. Start with one page and
+ * increase until buffer is sufficient or maxium size is
+ * reached
+ */
+static void kvm_flic_save(QEMUFile *f, void *opaque)
+{
+    KVMS390FLICState *flic = opaque;
+    int len = FLIC_SAVE_INITIAL_SIZE;
+    void *buf;
+    int count;
+
+    buf = g_try_malloc0(len);
+    if (!buf) {
+        /* Storing FLIC_FAILED into the count field here will cause the
+         * target system to fail when attempting to load irqs from the
+         * migration state */
+        error_report("flic: couldn't allocate memory");
+        qemu_put_be64(f, FLIC_FAILED);
+        return;
+    }
+
+    count = __get_all_irqs(flic, &buf, len);
+    if (count < 0) {
+        error_report("flic: couldn't retrieve irqs from kernel, rc %d",
+                     count);
+        /* Storing FLIC_FAILED into the count field here will cause the
+         * target system to fail when attempting to load irqs from the
+         * migration state */
+        qemu_put_be64(f, FLIC_FAILED);
+    } else {
+        qemu_put_be64(f, count);
+        qemu_put_buffer(f, (uint8_t *) buf,
+                        count * sizeof(struct kvm_s390_irq));
+    }
+    g_free(buf);
+}
+
+/**
+ * kvm_flic_load - Load pending floating interrupts
+ * @f: QEMUFile containing migration state
+ * @opaque: pointer to flic device state
+ * @version_id: version id for migration
+ *
+ * Returns: value of flic_enqueue_irqs, -EINVAL on error
+ * Note: Do nothing when no interrupts where stored
+ * in QEMUFile
+ */
+static int kvm_flic_load(QEMUFile *f, void *opaque, int version_id)
+{
+    uint64_t len = 0;
+    uint64_t count = 0;
+    void *buf = NULL;
+    int r = 0;
+
+    if (version_id != FLIC_SAVEVM_VERSION) {
+        r = -EINVAL;
+        goto out;
+    }
+
+    count = qemu_get_be64(f);
+    len = count * sizeof(struct kvm_s390_irq);
+    if (count == FLIC_FAILED) {
+        r = -EINVAL;
+        goto out;
+    }
+    if (count == 0) {
+        r = 0;
+        goto out;
+    }
+    buf = g_try_malloc0(len);
+    if (!buf) {
+        r = -ENOMEM;
+        goto out;
+    }
+
+    if (qemu_get_buffer(f, (uint8_t *) buf, len) != len) {
+        r = -EINVAL;
+        goto out_free;
+    }
+    r = flic_enqueue_irqs(buf, len, (struct KVMS390FLICState *) opaque);
+
+out_free:
+    g_free(buf);
+out:
+    return r;
+}
+
+static void kvm_s390_flic_realize(DeviceState *dev, Error **errp)
+{
+    KVMS390FLICState *flic_state = KVM_S390_FLIC(dev);
+    struct kvm_create_device cd = {0};
+    int ret;
+
+    flic_state->fd = -1;
+    if (!kvm_check_extension(kvm_state, KVM_CAP_DEVICE_CTRL)) {
+        trace_flic_no_device_api(errno);
+        return;
+    }
+
+    cd.type = KVM_DEV_TYPE_FLIC;
+    ret = kvm_vm_ioctl(kvm_state, KVM_CREATE_DEVICE, &cd);
+    if (ret < 0) {
+        trace_flic_create_device(errno);
+        return;
+    }
+    flic_state->fd = cd.fd;
+
+    /* Register savevm handler for floating interrupts */
+    register_savevm(NULL, "s390-flic", 0, 1, kvm_flic_save,
+                    kvm_flic_load, (void *) flic_state);
+}
+
+static void kvm_s390_flic_unrealize(DeviceState *dev, Error **errp)
+{
+    KVMS390FLICState *flic_state = KVM_S390_FLIC(dev);
+
+    unregister_savevm(DEVICE(flic_state), "s390-flic", flic_state);
+}
+
+static void kvm_s390_flic_reset(DeviceState *dev)
+{
+    KVMS390FLICState *flic = KVM_S390_FLIC(dev);
+    struct kvm_device_attr attr = {
+        .group = KVM_DEV_FLIC_CLEAR_IRQS,
+    };
+    int rc = 0;
+
+    if (flic->fd == -1) {
+        return;
+    }
+
+    rc = ioctl(flic->fd, KVM_SET_DEVICE_ATTR, &attr);
+    if (rc) {
+        trace_flic_reset_failed(errno);
+    }
+}
+
+static void kvm_s390_flic_class_init(ObjectClass *oc, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(oc);
+
+    dc->realize = kvm_s390_flic_realize;
+    dc->unrealize = kvm_s390_flic_unrealize;
+    dc->reset = kvm_s390_flic_reset;
+}
+
+static const TypeInfo kvm_s390_flic_info = {
+    .name          = TYPE_KVM_S390_FLIC,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(KVMS390FLICState),
+    .class_init    = kvm_s390_flic_class_init,
+};
+
+static void kvm_s390_flic_register_types(void)
+{
+    type_register_static(&kvm_s390_flic_info);
+}
+
+type_init(kvm_s390_flic_register_types)