Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 356 insertions, 0 deletions

diff --git a/hw/rtc/pl031.c b/hw/rtc/pl031.c
new file mode 100644
index 000000000..e7ced90b0
--- /dev/null
+++ b/hw/rtc/pl031.c
@@ -0,0 +1,356 @@
+/*
+ * ARM AMBA PrimeCell PL031 RTC
+ *
+ * Copyright (c) 2007 CodeSourcery
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Contributions after 2012-01-13 are licensed under the terms of the
+ * GNU GPL, version 2 or (at your option) any later version.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "hw/rtc/pl031.h"
+#include "migration/vmstate.h"
+#include "hw/irq.h"
+#include "hw/qdev-properties.h"
+#include "hw/sysbus.h"
+#include "qemu/timer.h"
+#include "sysemu/sysemu.h"
+#include "qemu/cutils.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+#include "trace.h"
+#include "qapi/qapi-events-misc-target.h"
+
+#define RTC_DR      0x00    /* Data read register */
+#define RTC_MR      0x04    /* Match register */
+#define RTC_LR      0x08    /* Data load register */
+#define RTC_CR      0x0c    /* Control register */
+#define RTC_IMSC    0x10    /* Interrupt mask and set register */
+#define RTC_RIS     0x14    /* Raw interrupt status register */
+#define RTC_MIS     0x18    /* Masked interrupt status register */
+#define RTC_ICR     0x1c    /* Interrupt clear register */
+
+static const unsigned char pl031_id[] = {
+    0x31, 0x10, 0x14, 0x00,         /* Device ID        */
+    0x0d, 0xf0, 0x05, 0xb1          /* Cell ID      */
+};
+
+static void pl031_update(PL031State *s)
+{
+    uint32_t flags = s->is & s->im;
+
+    trace_pl031_irq_state(flags);
+    qemu_set_irq(s->irq, flags);
+}
+
+static void pl031_interrupt(void * opaque)
+{
+    PL031State *s = (PL031State *)opaque;
+
+    s->is = 1;
+    trace_pl031_alarm_raised();
+    pl031_update(s);
+}
+
+static uint32_t pl031_get_count(PL031State *s)
+{
+    int64_t now = qemu_clock_get_ns(rtc_clock);
+    return s->tick_offset + now / NANOSECONDS_PER_SECOND;
+}
+
+static void pl031_set_alarm(PL031State *s)
+{
+    uint32_t ticks;
+
+    /* The timer wraps around.  This subtraction also wraps in the same way,
+       and gives correct results when alarm < now_ticks.  */
+    ticks = s->mr - pl031_get_count(s);
+    trace_pl031_set_alarm(ticks);
+    if (ticks == 0) {
+        timer_del(s->timer);
+        pl031_interrupt(s);
+    } else {
+        int64_t now = qemu_clock_get_ns(rtc_clock);
+        timer_mod(s->timer, now + (int64_t)ticks * NANOSECONDS_PER_SECOND);
+    }
+}
+
+static uint64_t pl031_read(void *opaque, hwaddr offset,
+                           unsigned size)
+{
+    PL031State *s = (PL031State *)opaque;
+    uint64_t r;
+
+    switch (offset) {
+    case RTC_DR:
+        r = pl031_get_count(s);
+        break;
+    case RTC_MR:
+        r = s->mr;
+        break;
+    case RTC_IMSC:
+        r = s->im;
+        break;
+    case RTC_RIS:
+        r = s->is;
+        break;
+    case RTC_LR:
+        r = s->lr;
+        break;
+    case RTC_CR:
+        /* RTC is permanently enabled.  */
+        r = 1;
+        break;
+    case RTC_MIS:
+        r = s->is & s->im;
+        break;
+    case 0xfe0 ... 0xfff:
+        r = pl031_id[(offset - 0xfe0) >> 2];
+        break;
+    case RTC_ICR:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "pl031: read of write-only register at offset 0x%x\n",
+                      (int)offset);
+        r = 0;
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "pl031_read: Bad offset 0x%x\n", (int)offset);
+        r = 0;
+        break;
+    }
+
+    trace_pl031_read(offset, r);
+    return r;
+}
+
+static void pl031_write(void * opaque, hwaddr offset,
+                        uint64_t value, unsigned size)
+{
+    PL031State *s = (PL031State *)opaque;
+
+    trace_pl031_write(offset, value);
+
+    switch (offset) {
+    case RTC_LR: {
+        struct tm tm;
+
+        s->tick_offset += value - pl031_get_count(s);
+
+        qemu_get_timedate(&tm, s->tick_offset);
+        qapi_event_send_rtc_change(qemu_timedate_diff(&tm));
+
+        pl031_set_alarm(s);
+        break;
+    }
+    case RTC_MR:
+        s->mr = value;
+        pl031_set_alarm(s);
+        break;
+    case RTC_IMSC:
+        s->im = value & 1;
+        pl031_update(s);
+        break;
+    case RTC_ICR:
+        s->is &= ~value;
+        pl031_update(s);
+        break;
+    case RTC_CR:
+        /* Written value is ignored.  */
+        break;
+
+    case RTC_DR:
+    case RTC_MIS:
+    case RTC_RIS:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "pl031: write to read-only register at offset 0x%x\n",
+                      (int)offset);
+        break;
+
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "pl031_write: Bad offset 0x%x\n", (int)offset);
+        break;
+    }
+}
+
+static const MemoryRegionOps pl031_ops = {
+    .read = pl031_read,
+    .write = pl031_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+};
+
+static void pl031_init(Object *obj)
+{
+    PL031State *s = PL031(obj);
+    SysBusDevice *dev = SYS_BUS_DEVICE(obj);
+    struct tm tm;
+
+    memory_region_init_io(&s->iomem, obj, &pl031_ops, s, "pl031", 0x1000);
+    sysbus_init_mmio(dev, &s->iomem);
+
+    sysbus_init_irq(dev, &s->irq);
+    qemu_get_timedate(&tm, 0);
+    s->tick_offset = mktimegm(&tm) -
+        qemu_clock_get_ns(rtc_clock) / NANOSECONDS_PER_SECOND;
+
+    s->timer = timer_new_ns(rtc_clock, pl031_interrupt, s);
+}
+
+static void pl031_finalize(Object *obj)
+{
+    PL031State *s = PL031(obj);
+
+    timer_free(s->timer);
+}
+
+static int pl031_pre_save(void *opaque)
+{
+    PL031State *s = opaque;
+
+    /*
+     * The PL031 device model code uses the tick_offset field, which is
+     * the offset between what the guest RTC should read and what the
+     * QEMU rtc_clock reads:
+     *  guest_rtc = rtc_clock + tick_offset
+     * and so
+     *  tick_offset = guest_rtc - rtc_clock
+     *
+     * We want to migrate this offset, which sounds straightforward.
+     * Unfortunately older versions of QEMU migrated a conversion of this
+     * offset into an offset from the vm_clock. (This was in turn an
+     * attempt to be compatible with even older QEMU versions, but it
+     * has incorrect behaviour if the rtc_clock is not the same as the
+     * vm_clock.) So we put the actual tick_offset into a migration
+     * subsection, and the backwards-compatible time-relative-to-vm_clock
+     * in the main migration state.
+     *
+     * Calculate base time relative to QEMU_CLOCK_VIRTUAL:
+     */
+    int64_t delta = qemu_clock_get_ns(rtc_clock) - qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+    s->tick_offset_vmstate = s->tick_offset + delta / NANOSECONDS_PER_SECOND;
+
+    return 0;
+}
+
+static int pl031_pre_load(void *opaque)
+{
+    PL031State *s = opaque;
+
+    s->tick_offset_migrated = false;
+    return 0;
+}
+
+static int pl031_post_load(void *opaque, int version_id)
+{
+    PL031State *s = opaque;
+
+    /*
+     * If we got the tick_offset subsection, then we can just use
+     * the value in that. Otherwise the source is an older QEMU and
+     * has given us the offset from the vm_clock; convert it back to
+     * an offset from the rtc_clock. This will cause time to incorrectly
+     * go backwards compared to the host RTC, but this is unavoidable.
+     */
+
+    if (!s->tick_offset_migrated) {
+        int64_t delta = qemu_clock_get_ns(rtc_clock) -
+            qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+        s->tick_offset = s->tick_offset_vmstate -
+            delta / NANOSECONDS_PER_SECOND;
+    }
+    pl031_set_alarm(s);
+    return 0;
+}
+
+static int pl031_tick_offset_post_load(void *opaque, int version_id)
+{
+    PL031State *s = opaque;
+
+    s->tick_offset_migrated = true;
+    return 0;
+}
+
+static bool pl031_tick_offset_needed(void *opaque)
+{
+    PL031State *s = opaque;
+
+    return s->migrate_tick_offset;
+}
+
+static const VMStateDescription vmstate_pl031_tick_offset = {
+    .name = "pl031/tick-offset",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = pl031_tick_offset_needed,
+    .post_load = pl031_tick_offset_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(tick_offset, PL031State),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription vmstate_pl031 = {
+    .name = "pl031",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .pre_save = pl031_pre_save,
+    .pre_load = pl031_pre_load,
+    .post_load = pl031_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(tick_offset_vmstate, PL031State),
+        VMSTATE_UINT32(mr, PL031State),
+        VMSTATE_UINT32(lr, PL031State),
+        VMSTATE_UINT32(cr, PL031State),
+        VMSTATE_UINT32(im, PL031State),
+        VMSTATE_UINT32(is, PL031State),
+        VMSTATE_END_OF_LIST()
+    },
+    .subsections = (const VMStateDescription*[]) {
+        &vmstate_pl031_tick_offset,
+        NULL
+    }
+};
+
+static Property pl031_properties[] = {
+    /*
+     * True to correctly migrate the tick offset of the RTC. False to
+     * obtain backward migration compatibility with older QEMU versions,
+     * at the expense of the guest RTC going backwards compared with the
+     * host RTC when the VM is saved/restored if using -rtc host.
+     * (Even if set to 'true' older QEMU can migrate forward to newer QEMU;
+     * 'false' also permits newer QEMU to migrate to older QEMU.)
+     */
+    DEFINE_PROP_BOOL("migrate-tick-offset",
+                     PL031State, migrate_tick_offset, true),
+    DEFINE_PROP_END_OF_LIST()
+};
+
+static void pl031_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->vmsd = &vmstate_pl031;
+    device_class_set_props(dc, pl031_properties);
+}
+
+static const TypeInfo pl031_info = {
+    .name          = TYPE_PL031,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(PL031State),
+    .instance_init = pl031_init,
+    .instance_finalize = pl031_finalize,
+    .class_init    = pl031_class_init,
+};
+
+static void pl031_register_types(void)
+{
+    type_register_static(&pl031_info);
+}
+
+type_init(pl031_register_types)