qemu/hw/virtio/virtio-rng.c

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/*
* A virtio device implementing a hardware random number generator.
*
* Copyright 2012 Red Hat, Inc.
* Copyright 2012 Amit Shah <amit.shah@redhat.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 "qemu/osdep.h"
2016-03-14 11:01:28 +03:00
#include "qapi/error.h"
#include "qemu/iov.h"
#include "qemu/module.h"
#include "qemu/timer.h"
#include "hw/virtio/virtio.h"
#include "hw/qdev-properties.h"
#include "hw/virtio/virtio-rng.h"
#include "sysemu/rng.h"
#include "sysemu/runstate.h"
#include "qom/object_interfaces.h"
#include "trace.h"
static bool is_guest_ready(VirtIORNG *vrng)
{
VirtIODevice *vdev = VIRTIO_DEVICE(vrng);
if (virtio_queue_ready(vrng->vq)
&& (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
return true;
}
trace_virtio_rng_guest_not_ready(vrng);
return false;
}
static size_t get_request_size(VirtQueue *vq, unsigned quota)
{
unsigned int in, out;
virtqueue_get_avail_bytes(vq, &in, &out, quota, 0);
return in;
}
static void virtio_rng_process(VirtIORNG *vrng);
/* Send data from a char device over to the guest */
static void chr_read(void *opaque, const void *buf, size_t size)
{
VirtIORNG *vrng = opaque;
VirtIODevice *vdev = VIRTIO_DEVICE(vrng);
VirtQueueElement *elem;
size_t len;
int offset;
if (!is_guest_ready(vrng)) {
return;
}
/* we can't modify the virtqueue until
* our state is fully synced
*/
if (!runstate_check(RUN_STATE_RUNNING)) {
trace_virtio_rng_cpu_is_stopped(vrng, size);
return;
}
vrng->quota_remaining -= size;
offset = 0;
while (offset < size) {
elem = virtqueue_pop(vrng->vq, sizeof(VirtQueueElement));
if (!elem) {
break;
}
trace_virtio_rng_popped(vrng);
len = iov_from_buf(elem->in_sg, elem->in_num,
0, buf + offset, size - offset);
offset += len;
virtqueue_push(vrng->vq, elem, len);
trace_virtio_rng_pushed(vrng, len);
g_free(elem);
}
virtio_notify(vdev, vrng->vq);
if (!virtio_queue_empty(vrng->vq)) {
/* If we didn't drain the queue, call virtio_rng_process
* to take care of asking for more data as appropriate.
*/
virtio_rng_process(vrng);
}
}
static void virtio_rng_process(VirtIORNG *vrng)
{
size_t size;
unsigned quota;
if (!is_guest_ready(vrng)) {
return;
}
if (vrng->activate_timer) {
timer_mod(vrng->rate_limit_timer,
qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms);
vrng->activate_timer = false;
}
if (vrng->quota_remaining < 0) {
quota = 0;
} else {
quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX);
}
size = get_request_size(vrng->vq, quota);
trace_virtio_rng_request(vrng, size, quota);
size = MIN(vrng->quota_remaining, size);
if (size) {
rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);
}
}
static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIORNG *vrng = VIRTIO_RNG(vdev);
virtio_rng_process(vrng);
}
static uint64_t get_features(VirtIODevice *vdev, uint64_t f, Error **errp)
{
return f;
}
static void virtio_rng_vm_state_change(void *opaque, int running,
RunState state)
{
Fix for crash after migration in virtio-rng on bi-endian targets VirtIO devices now remember which endianness they're operating in in order to support targets which may have guests of either endianness, such as powerpc. This endianness state is transferred in a subsection of the virtio device's information. With virtio-rng this can lead to an abort after a loadvm hitting the assert() in virtio_is_big_endian(). This can be reproduced by doing a migrate and load from file on a bi-endian target with a virtio-rng device. The actual guest state isn't particularly important to triggering this. The cause is that virtio_rng_load_device() calls virtio_rng_process() which accesses the ring and thus needs the endianness. However, virtio_rng_process() is called via virtio_load() before it loads the subsections. Essentially the ->load callback in VirtioDeviceClass should only be used for actually reading the device state from the stream, not for post-load re-initialization. This patch fixes the bug by moving the virtio_rng_process() after the call to virtio_load(). Better yet would be to convert virtio to use vmsd and have the virtio_rng_process() as a post_load callback, but that's a bigger project for another day. This is bugfix, and should be considered for the 2.2 branch. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Message-id: 1417067290-20715-1-git-send-email-david@gibson.dropbear.id.au Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-11-27 08:48:10 +03:00
VirtIORNG *vrng = opaque;
trace_virtio_rng_vm_state_change(vrng, running, state);
/* We may have an element ready but couldn't process it due to a quota
* limit or because CPU was stopped. Make sure to try again when the
* CPU restart.
*/
if (running && is_guest_ready(vrng)) {
virtio_rng_process(vrng);
}
}
static void check_rate_limit(void *opaque)
{
VirtIORNG *vrng = opaque;
vrng->quota_remaining = vrng->conf.max_bytes;
virtio_rng_process(vrng);
vrng->activate_timer = true;
}
static void virtio_rng_set_status(VirtIODevice *vdev, uint8_t status)
{
VirtIORNG *vrng = VIRTIO_RNG(vdev);
if (!vdev->vm_running) {
return;
}
vdev->status = status;
/* Something changed, try to process buffers */
virtio_rng_process(vrng);
}
static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIORNG *vrng = VIRTIO_RNG(dev);
if (vrng->conf.period_ms <= 0) {
error_setg(errp, "'period' parameter expects a positive integer");
return;
}
/* Workaround: Property parsing does not enforce unsigned integers,
* So this is a hack to reject such numbers. */
if (vrng->conf.max_bytes > INT64_MAX) {
error_setg(errp, "'max-bytes' parameter must be non-negative, "
"and less than 2^63");
return;
}
if (vrng->conf.rng == NULL) {
Object *default_backend = object_new(TYPE_RNG_BUILTIN);
if (!user_creatable_complete(USER_CREATABLE(default_backend),
error: Eliminate error_propagate() with Coccinelle, part 1 When all we do with an Error we receive into a local variable is propagating to somewhere else, we can just as well receive it there right away. Convert if (!foo(..., &err)) { ... error_propagate(errp, err); ... return ... } to if (!foo(..., errp)) { ... ... return ... } where nothing else needs @err. Coccinelle script: @rule1 forall@ identifier fun, err, errp, lbl; expression list args, args2; binary operator op; constant c1, c2; symbol false; @@ if ( ( - fun(args, &err, args2) + fun(args, errp, args2) | - !fun(args, &err, args2) + !fun(args, errp, args2) | - fun(args, &err, args2) op c1 + fun(args, errp, args2) op c1 ) ) { ... when != err when != lbl: when strict - error_propagate(errp, err); ... when != err ( return; | return c2; | return false; ) } @rule2 forall@ identifier fun, err, errp, lbl; expression list args, args2; expression var; binary operator op; constant c1, c2; symbol false; @@ - var = fun(args, &err, args2); + var = fun(args, errp, args2); ... when != err if ( ( var | !var | var op c1 ) ) { ... when != err when != lbl: when strict - error_propagate(errp, err); ... when != err ( return; | return c2; | return false; | return var; ) } @depends on rule1 || rule2@ identifier err; @@ - Error *err = NULL; ... when != err Not exactly elegant, I'm afraid. The "when != lbl:" is necessary to avoid transforming if (fun(args, &err)) { goto out } ... out: error_propagate(errp, err); even though other paths to label out still need the error_propagate(). For an actual example, see sclp_realize(). Without the "when strict", Coccinelle transforms vfio_msix_setup(), incorrectly. I don't know what exactly "when strict" does, only that it helps here. The match of return is narrower than what I want, but I can't figure out how to express "return where the operand doesn't use @err". For an example where it's too narrow, see vfio_intx_enable(). Silently fails to convert hw/arm/armsse.c, because Coccinelle gets confused by ARMSSE being used both as typedef and function-like macro there. Converted manually. Line breaks tidied up manually. One nested declaration of @local_err deleted manually. Preexisting unwanted blank line dropped in hw/riscv/sifive_e.c. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200707160613.848843-35-armbru@redhat.com>
2020-07-07 19:06:02 +03:00
errp)) {
object_unref(default_backend);
return;
}
object_property_add_child(OBJECT(dev), "default-backend",
qom: Drop parameter @errp of object_property_add() & friends The only way object_property_add() can fail is when a property with the same name already exists. Since our property names are all hardcoded, failure is a programming error, and the appropriate way to handle it is passing &error_abort. Same for its variants, except for object_property_add_child(), which additionally fails when the child already has a parent. Parentage is also under program control, so this is a programming error, too. We have a bit over 500 callers. Almost half of them pass &error_abort, slightly fewer ignore errors, one test case handles errors, and the remaining few callers pass them to their own callers. The previous few commits demonstrated once again that ignoring programming errors is a bad idea. Of the few ones that pass on errors, several violate the Error API. The Error ** argument must be NULL, &error_abort, &error_fatal, or a pointer to a variable containing NULL. Passing an argument of the latter kind twice without clearing it in between is wrong: if the first call sets an error, it no longer points to NULL for the second call. ich9_pm_add_properties(), sparc32_ledma_realize(), sparc32_dma_realize(), xilinx_axidma_realize(), xilinx_enet_realize() are wrong that way. When the one appropriate choice of argument is &error_abort, letting users pick the argument is a bad idea. Drop parameter @errp and assert the preconditions instead. There's one exception to "duplicate property name is a programming error": the way object_property_add() implements the magic (and undocumented) "automatic arrayification". Don't drop @errp there. Instead, rename object_property_add() to object_property_try_add(), and add the obvious wrapper object_property_add(). Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20200505152926.18877-15-armbru@redhat.com> [Two semantic rebase conflicts resolved]
2020-05-05 18:29:22 +03:00
default_backend);
/* The child property took a reference, we can safely drop ours now */
object_unref(default_backend);
qom: Put name parameter before value / visitor parameter The object_property_set_FOO() setters take property name and value in an unusual order: void object_property_set_FOO(Object *obj, FOO_TYPE value, const char *name, Error **errp) Having to pass value before name feels grating. Swap them. Same for object_property_set(), object_property_get(), and object_property_parse(). Convert callers with this Coccinelle script: @@ identifier fun = { object_property_get, object_property_parse, object_property_set_str, object_property_set_link, object_property_set_bool, object_property_set_int, object_property_set_uint, object_property_set, object_property_set_qobject }; expression obj, v, name, errp; @@ - fun(obj, v, name, errp) + fun(obj, name, v, errp) Chokes on hw/arm/musicpal.c's lcd_refresh() with the unhelpful error message "no position information". Convert that one manually. Fails to convert hw/arm/armsse.c, because Coccinelle gets confused by ARMSSE being used both as typedef and function-like macro there. Convert manually. Fails to convert hw/rx/rx-gdbsim.c, because Coccinelle gets confused by RXCPU being used both as typedef and function-like macro there. Convert manually. The other files using RXCPU that way don't need conversion. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200707160613.848843-27-armbru@redhat.com> [Straightforwad conflict with commit 2336172d9b "audio: set default value for pcspk.iobase property" resolved]
2020-07-07 19:05:54 +03:00
object_property_set_link(OBJECT(dev), "rng", default_backend,
&error_abort);
}
vrng->rng = vrng->conf.rng;
if (vrng->rng == NULL) {
error_setg(errp, "'rng' parameter expects a valid object");
return;
}
virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0);
vrng->vq = virtio_add_queue(vdev, 8, handle_input);
vrng->quota_remaining = vrng->conf.max_bytes;
vrng->rate_limit_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
check_rate_limit, vrng);
vrng->activate_timer = true;
vrng->vmstate = qemu_add_vm_change_state_handler(virtio_rng_vm_state_change,
vrng);
}
qdev: Unrealize must not fail Devices may have component devices and buses. Device realization may fail. Realization is recursive: a device's realize() method realizes its components, and device_set_realized() realizes its buses (which should in turn realize the devices on that bus, except bus_set_realized() doesn't implement that, yet). When realization of a component or bus fails, we need to roll back: unrealize everything we realized so far. If any of these unrealizes failed, the device would be left in an inconsistent state. Must not happen. device_set_realized() lets it happen: it ignores errors in the roll back code starting at label child_realize_fail. Since realization is recursive, unrealization must be recursive, too. But how could a partly failed unrealize be rolled back? We'd have to re-realize, which can fail. This design is fundamentally broken. device_set_realized() does not roll back at all. Instead, it keeps unrealizing, ignoring further errors. It can screw up even for a device with no buses: if the lone dc->unrealize() fails, it still unregisters vmstate, and calls listeners' unrealize() callback. bus_set_realized() does not roll back either. Instead, it stops unrealizing. Fortunately, no unrealize method can fail, as we'll see below. To fix the design error, drop parameter @errp from all the unrealize methods. Any unrealize method that uses @errp now needs an update. This leads us to unrealize() methods that can fail. Merely passing it to another unrealize method cannot cause failure, though. Here are the ones that do other things with @errp: * virtio_serial_device_unrealize() Fails when qbus_set_hotplug_handler() fails, but still does all the other work. On failure, the device would stay realized with its resources completely gone. Oops. Can't happen, because qbus_set_hotplug_handler() can't actually fail here. Pass &error_abort to qbus_set_hotplug_handler() instead. * hw/ppc/spapr_drc.c's unrealize() Fails when object_property_del() fails, but all the other work is already done. On failure, the device would stay realized with its vmstate registration gone. Oops. Can't happen, because object_property_del() can't actually fail here. Pass &error_abort to object_property_del() instead. * spapr_phb_unrealize() Fails and bails out when remove_drcs() fails, but other work is already done. On failure, the device would stay realized with some of its resources gone. Oops. remove_drcs() fails only when chassis_from_bus()'s object_property_get_uint() fails, and it can't here. Pass &error_abort to remove_drcs() instead. Therefore, no unrealize method can fail before this patch. device_set_realized()'s recursive unrealization via bus uses object_property_set_bool(). Can't drop @errp there, so pass &error_abort. We similarly unrealize with object_property_set_bool() elsewhere, always ignoring errors. Pass &error_abort instead. Several unrealize methods no longer handle errors from other unrealize methods: virtio_9p_device_unrealize(), virtio_input_device_unrealize(), scsi_qdev_unrealize(), ... Much of the deleted error handling looks wrong anyway. One unrealize methods no longer ignore such errors: usb_ehci_pci_exit(). Several realize methods no longer ignore errors when rolling back: v9fs_device_realize_common(), pci_qdev_unrealize(), spapr_phb_realize(), usb_qdev_realize(), vfio_ccw_realize(), virtio_device_realize(). Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20200505152926.18877-17-armbru@redhat.com>
2020-05-05 18:29:24 +03:00
static void virtio_rng_device_unrealize(DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIORNG *vrng = VIRTIO_RNG(dev);
qemu_del_vm_change_state_handler(vrng->vmstate);
timer_del(vrng->rate_limit_timer);
timer_free(vrng->rate_limit_timer);
virtio_del_queue(vdev, 0);
virtio_cleanup(vdev);
}
static const VMStateDescription vmstate_virtio_rng = {
.name = "virtio-rng",
.minimum_version_id = 1,
.version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_VIRTIO_DEVICE,
VMSTATE_END_OF_LIST()
},
};
static Property virtio_rng_properties[] = {
/* Set a default rate limit of 2^47 bytes per minute or roughly 2TB/s. If
* you have an entropy source capable of generating more entropy than this
* and you can pass it through via virtio-rng, then hats off to you. Until
* then, this is unlimited for all practical purposes.
*/
DEFINE_PROP_UINT64("max-bytes", VirtIORNG, conf.max_bytes, INT64_MAX),
DEFINE_PROP_UINT32("period", VirtIORNG, conf.period_ms, 1 << 16),
DEFINE_PROP_LINK("rng", VirtIORNG, conf.rng, TYPE_RNG_BACKEND, RngBackend *),
DEFINE_PROP_END_OF_LIST(),
};
static void virtio_rng_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
device_class_set_props(dc, virtio_rng_properties);
dc->vmsd = &vmstate_virtio_rng;
set_bit(DEVICE_CATEGORY_MISC, dc->categories);
vdc->realize = virtio_rng_device_realize;
vdc->unrealize = virtio_rng_device_unrealize;
vdc->get_features = get_features;
vdc->set_status = virtio_rng_set_status;
}
static const TypeInfo virtio_rng_info = {
.name = TYPE_VIRTIO_RNG,
.parent = TYPE_VIRTIO_DEVICE,
.instance_size = sizeof(VirtIORNG),
.class_init = virtio_rng_class_init,
};
static void virtio_register_types(void)
{
type_register_static(&virtio_rng_info);
}
type_init(virtio_register_types)