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Merge branch '2022-06-08-virtio-harden-and-test-vring' into next

Browse Source 
To quote the author:
Make the virtio ring code resilient against corruption of the buffers
shared with the device.

It follows the example of Linux by keeping a private copy of the
descriptors and metadata for state tracking and only ever writing to the
descriptors that are shared with the device. I was able to test these
hardening steps in the sandbox by simulating device writes to the
queues.
This commit is contained in:
Tom Rini 2022-06-08 11:15:28 -04:00
commit c0e63bf468
8 changed files with 330 additions and 137 deletions
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96
drivers/virtio/virtio_ring.c
View File

@ -16,21 +16,40 @@
#include <linux/bug.h>
#include <linux/compat.h>
static unsigned int virtqueue_attach_desc(struct virtqueue *vq, unsigned int i,
struct virtio_sg *sg, u16 flags)
{
struct vring_desc_shadow *desc_shadow = &vq->vring_desc_shadow[i];
struct vring_desc *desc = &vq->vring.desc[i];
/* Update the shadow descriptor. */
desc_shadow->addr = (u64)(uintptr_t)sg->addr;
desc_shadow->len = sg->length;
desc_shadow->flags = flags;
/* Update the shared descriptor to match the shadow. */
desc->addr = cpu_to_virtio64(vq->vdev, desc_shadow->addr);
desc->len = cpu_to_virtio32(vq->vdev, desc_shadow->len);
desc->flags = cpu_to_virtio16(vq->vdev, desc_shadow->flags);
desc->next = cpu_to_virtio16(vq->vdev, desc_shadow->next);
return desc_shadow->next;
}
int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[],
unsigned int out_sgs, unsigned int in_sgs)
{
struct vring_desc *desc;
unsigned int total_sg = out_sgs + in_sgs;
unsigned int i, n, avail, descs_used, uninitialized_var(prev);
unsigned int descs_used = out_sgs + in_sgs;
unsigned int i, n, avail, uninitialized_var(prev);
int head;
WARN_ON(total_sg == 0);
WARN_ON(descs_used == 0);
head = vq->free_head;
desc = vq->vring.desc;
i = head;
descs_used = total_sg;
if (vq->num_free < descs_used) {
debug("Can't add buf len %i - avail = %i\n",
@ -45,30 +64,17 @@ int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[],
return -ENOSPC;
}
for (n = 0; n < out_sgs; n++) {
struct virtio_sg *sg = sgs[n];
desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT);
desc[i].addr = cpu_to_virtio64(vq->vdev, (u64)(size_t)sg->addr);
desc[i].len = cpu_to_virtio32(vq->vdev, sg->length);
for (n = 0; n < descs_used; n++) {
u16 flags = VRING_DESC_F_NEXT;
if (n >= out_sgs)
flags |= VRING_DESC_F_WRITE;
prev = i;
i = virtio16_to_cpu(vq->vdev, desc[i].next);
}
for (; n < (out_sgs + in_sgs); n++) {
struct virtio_sg *sg = sgs[n];
desc[i].flags = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT |
VRING_DESC_F_WRITE);
desc[i].addr = cpu_to_virtio64(vq->vdev,
(u64)(uintptr_t)sg->addr);
desc[i].len = cpu_to_virtio32(vq->vdev, sg->length);
prev = i;
i = virtio16_to_cpu(vq->vdev, desc[i].next);
i = virtqueue_attach_desc(vq, i, sgs[n], flags);
}
/* Last one doesn't continue */
desc[prev].flags &= cpu_to_virtio16(vq->vdev, ~VRING_DESC_F_NEXT);
vq->vring_desc_shadow[prev].flags &= ~VRING_DESC_F_NEXT;
desc[prev].flags = cpu_to_virtio16(vq->vdev, vq->vring_desc_shadow[prev].flags);
/* We're using some buffers from the free list. */
vq->num_free -= descs_used;
@ -76,6 +82,9 @@ int virtqueue_add(struct virtqueue *vq, struct virtio_sg *sgs[],
/* Update free pointer */
vq->free_head = i;
/* Mark the descriptor as the head of a chain. */
vq->vring_desc_shadow[head].chain_head = true;
/*
* Put entry in available array (but don't update avail->idx
* until they do sync).
@ -137,17 +146,19 @@ void virtqueue_kick(struct virtqueue *vq)
static void detach_buf(struct virtqueue *vq, unsigned int head)
{
unsigned int i;
__virtio16 nextflag = cpu_to_virtio16(vq->vdev, VRING_DESC_F_NEXT);
/* Unmark the descriptor as the head of a chain. */
vq->vring_desc_shadow[head].chain_head = false;
/* Put back on free list: unmap first-level descriptors and find end */
i = head;
while (vq->vring.desc[i].flags & nextflag) {
i = virtio16_to_cpu(vq->vdev, vq->vring.desc[i].next);
while (vq->vring_desc_shadow[i].flags & VRING_DESC_F_NEXT) {
i = vq->vring_desc_shadow[i].next;
vq->num_free++;
}
vq->vring.desc[i].next = cpu_to_virtio16(vq->vdev, vq->free_head);
vq->vring_desc_shadow[i].next = vq->free_head;
vq->free_head = head;
/* Plus final descriptor */
@ -189,6 +200,12 @@ void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len)
return NULL;
}
if (unlikely(!vq->vring_desc_shadow[i].chain_head)) {
printf("(%s.%d): id %u is not a head\n",
vq->vdev->name, vq->index, i);
return NULL;
}
detach_buf(vq, i);
vq->last_used_idx++;
/*
@ -200,8 +217,7 @@ void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len)
virtio_store_mb(&vring_used_event(&vq->vring),
cpu_to_virtio16(vq->vdev, vq->last_used_idx));
return (void *)(uintptr_t)virtio64_to_cpu(vq->vdev,
vq->vring.desc[i].addr);
return (void *)(uintptr_t)vq->vring_desc_shadow[i].addr;
}
static struct virtqueue *__vring_new_virtqueue(unsigned int index,
@ -210,6 +226,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index,
{
unsigned int i;
struct virtqueue *vq;
struct vring_desc_shadow *vring_desc_shadow;
struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
struct udevice *vdev = uc_priv->vdev;
@ -217,10 +234,17 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index,
if (!vq)
return NULL;
vring_desc_shadow = calloc(vring.num, sizeof(struct vring_desc_shadow));
if (!vring_desc_shadow) {
free(vq);
return NULL;
}
vq->vdev = vdev;
vq->index = index;
vq->num_free = vring.num;
vq->vring = vring;
vq->vring_desc_shadow = vring_desc_shadow;
vq->last_used_idx = 0;
vq->avail_flags_shadow = 0;
vq->avail_idx_shadow = 0;
@ -238,7 +262,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index,
/* Put everything in free lists */
vq->free_head = 0;
for (i = 0; i < vring.num - 1; i++)
vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
vq->vring_desc_shadow[i].next = i + 1;
return vq;
}
@ -291,6 +315,7 @@ struct virtqueue *vring_create_virtqueue(unsigned int index, unsigned int num,
void vring_del_virtqueue(struct virtqueue *vq)
{
free(vq->vring.desc);
free(vq->vring_desc_shadow);
list_del(&vq->list);
free(vq);
}
@ -336,11 +361,12 @@ void virtqueue_dump(struct virtqueue *vq)
printf("\tlast_used_idx %u, avail_flags_shadow %u, avail_idx_shadow %u\n",
vq->last_used_idx, vq->avail_flags_shadow, vq->avail_idx_shadow);
printf("Descriptor dump:\n");
printf("Shadow descriptor dump:\n");
for (i = 0; i < vq->vring.num; i++) {
printf("\tdesc[%u] = { 0x%llx, len %u, flags %u, next %u }\n",
i, vq->vring.desc[i].addr, vq->vring.desc[i].len,
vq->vring.desc[i].flags, vq->vring.desc[i].next);
struct vring_desc_shadow *desc = &vq->vring_desc_shadow[i];
printf("\tdesc_shadow[%u] = { 0x%llx, len %u, flags %u, next %u }\n",
i, desc->addr, desc->len, desc->flags, desc->next);
}
printf("Avail ring dump:\n");

3
drivers/virtio/virtio_rng.c
View File

@ -41,6 +41,9 @@ static int virtio_rng_read(struct udevice *dev, void *data, size_t len)
while (!virtqueue_get_buf(priv->rng_vq, &rsize))
;
if (rsize > sg.length)
return -EIO;
memcpy(ptr, buf, rsize);
len -= rsize;
ptr += rsize;

4
drivers/virtio/virtio_sandbox.c
View File

@ -160,8 +160,8 @@ static int virtio_sandbox_probe(struct udevice *udev)
struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
/* fake some information for testing */
priv->device_features = VIRTIO_F_VERSION_1;
uc_priv->device = VIRTIO_ID_BLOCK;
priv->device_features = BIT_ULL(VIRTIO_F_VERSION_1);
uc_priv->device = VIRTIO_ID_RNG;
uc_priv->vendor = ('u' << 24) | ('b' << 16) | ('o' << 8) | 't';
return 0;

12
include/virtio_ring.h
View File

@ -55,6 +55,16 @@ struct vring_desc {
__virtio16 next;
};
/* Shadow of struct vring_desc in guest byte order. */
struct vring_desc_shadow {
u64 addr;
u32 len;
u16 flags;
u16 next;
/* Metadata about the descriptor. */
bool chain_head;
};
struct vring_avail {
__virtio16 flags;
__virtio16 idx;
@ -89,6 +99,7 @@ struct vring {
* @index: the zero-based ordinal number for this queue
* @num_free: number of elements we expect to be able to fit
* @vring: actual memory layout for this queue
* @vring_desc_shadow: guest-only copy of descriptors
* @event: host publishes avail event idx
* @free_head: head of free buffer list
* @num_added: number we've added since last sync
@ -102,6 +113,7 @@ struct virtqueue {
unsigned int index;
unsigned int num_free;
struct vring vring;
struct vring_desc_shadow *vring_desc_shadow;
bool event;
unsigned int free_head;
unsigned int num_added;

6
test/dm/Makefile
View File

@ -107,7 +107,11 @@ obj-$(CONFIG_TEE) += tee.o
obj-$(CONFIG_TIMER) += timer.o
obj-$(CONFIG_DM_USB) += usb.o
obj-$(CONFIG_DM_VIDEO) += video.o
obj-$(CONFIG_VIRTIO_SANDBOX) += virtio.o
ifeq ($(CONFIG_VIRTIO_SANDBOX),y)
obj-y += virtio.o
obj-$(CONFIG_VIRTIO_RNG) += virtio_device.o
obj-$(CONFIG_VIRTIO_RNG) += virtio_rng.o
endif
ifeq ($(CONFIG_WDT_GPIO)$(CONFIG_WDT_SANDBOX),yy)
obj-y += wdt.o
endif

99
test/dm/virtio.c
View File

@ -7,7 +7,6 @@
#include <dm.h>
#include <virtio_types.h>
#include <virtio.h>
#include <virtio_ring.h>
#include <dm/device-internal.h>
#include <dm/root.h>
#include <dm/test.h>
@ -15,78 +14,6 @@
#include <test/test.h>
#include <test/ut.h>
/* Basic test of the virtio uclass */
static int dm_test_virtio_base(struct unit_test_state *uts)
{
struct udevice *bus, *dev;
u8 status;
/* check probe success */
ut_assertok(uclass_first_device(UCLASS_VIRTIO, &bus));
ut_assertnonnull(bus);
/* check the child virtio-blk device is bound */
ut_assertok(device_find_first_child(bus, &dev));
ut_assertnonnull(dev);
ut_assertok(strcmp(dev->name, "virtio-blk#0"));
/* check driver status */
ut_assertok(virtio_get_status(dev, &status));
ut_asserteq(VIRTIO_CONFIG_S_ACKNOWLEDGE, status);
return 0;
}
DM_TEST(dm_test_virtio_base, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
/* Test all of the virtio uclass ops */
static int dm_test_virtio_all_ops(struct unit_test_state *uts)
{
struct udevice *bus, *dev;
struct virtio_dev_priv *uc_priv;
uint offset = 0, len = 0, nvqs = 1;
void *buffer = NULL;
u8 status;
u32 counter;
u64 features;
struct virtqueue *vqs[2];
/* check probe success */
ut_assertok(uclass_first_device(UCLASS_VIRTIO, &bus));
ut_assertnonnull(bus);
/* check the child virtio-blk device is bound */
ut_assertok(device_find_first_child(bus, &dev));
ut_assertnonnull(dev);
/*
* fake the virtio device probe by filling in uc_priv->vdev
* which is used by virtio_find_vqs/virtio_del_vqs.
*/
uc_priv = dev_get_uclass_priv(bus);
ut_assertnonnull(uc_priv);
uc_priv->vdev = dev;
/* test virtio_xxx APIs */
ut_assertok(virtio_get_config(dev, offset, buffer, len));
ut_assertok(virtio_set_config(dev, offset, buffer, len));
ut_asserteq(-ENOSYS, virtio_generation(dev, &counter));
ut_assertok(virtio_set_status(dev, VIRTIO_CONFIG_S_DRIVER_OK));
ut_assertok(virtio_get_status(dev, &status));
ut_asserteq(VIRTIO_CONFIG_S_DRIVER_OK, status);
ut_assertok(virtio_reset(dev));
ut_assertok(virtio_get_status(dev, &status));
ut_asserteq(0, status);
ut_assertok(virtio_get_features(dev, &features));
ut_asserteq(VIRTIO_F_VERSION_1, features);
ut_assertok(virtio_set_features(dev));
ut_assertok(virtio_find_vqs(dev, nvqs, vqs));
ut_assertok(virtio_del_vqs(dev));
ut_assertok(virtio_notify(dev, vqs[0]));
return 0;
}
DM_TEST(dm_test_virtio_all_ops, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
/* Test of the virtio driver that does not have required driver ops */
static int dm_test_virtio_missing_ops(struct unit_test_state *uts)
{
@ -104,29 +31,3 @@ static int dm_test_virtio_missing_ops(struct unit_test_state *uts)
return 0;
}
DM_TEST(dm_test_virtio_missing_ops, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
/* Test removal of virtio device driver */
static int dm_test_virtio_remove(struct unit_test_state *uts)
{
struct udevice *bus, *dev;
/* check probe success */
ut_assertok(uclass_first_device(UCLASS_VIRTIO, &bus));
ut_assertnonnull(bus);
/* check the child virtio-blk device is bound */
ut_assertok(device_find_first_child(bus, &dev));
ut_assertnonnull(dev);
/* set driver status to VIRTIO_CONFIG_S_DRIVER_OK */
ut_assertok(virtio_set_status(dev, VIRTIO_CONFIG_S_DRIVER_OK));
/* check the device can be successfully removed */
dev_or_flags(dev, DM_FLAG_ACTIVATED);
ut_asserteq(-EKEYREJECTED, device_remove(bus, DM_REMOVE_ACTIVE_ALL));
ut_asserteq(false, device_active(dev));
return 0;
}
DM_TEST(dm_test_virtio_remove, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);

195
test/dm/virtio_device.c Normal file
View File

@ -0,0 +1,195 @@
// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
*/
#include <common.h>
#include <dm.h>
#include <virtio_types.h>
#include <virtio.h>
#include <virtio_ring.h>
#include <dm/device-internal.h>
#include <dm/root.h>
#include <dm/test.h>
#include <dm/uclass-internal.h>
#include <test/test.h>
#include <test/ut.h>
/* Basic test of the virtio uclass */
static int dm_test_virtio_base(struct unit_test_state *uts)
{
struct udevice *bus, *dev;
u8 status;
/* check probe success */
ut_assertok(uclass_first_device(UCLASS_VIRTIO, &bus));
ut_assertnonnull(bus);
/* check the child virtio-rng device is bound */
ut_assertok(device_find_first_child(bus, &dev));
ut_assertnonnull(dev);
ut_asserteq_str("virtio-rng#0", dev->name);
/* check driver status */
ut_assertok(virtio_get_status(dev, &status));
ut_asserteq(VIRTIO_CONFIG_S_ACKNOWLEDGE, status);
/* probe the virtio-rng driver */
ut_assertok(device_probe(dev));
/* check the device was reset and the driver picked up the device */
ut_assertok(virtio_get_status(dev, &status));
ut_asserteq(VIRTIO_CONFIG_S_DRIVER |
VIRTIO_CONFIG_S_DRIVER_OK |
VIRTIO_CONFIG_S_FEATURES_OK, status);
return 0;
}
DM_TEST(dm_test_virtio_base, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
/* Test all of the virtio uclass ops */
static int dm_test_virtio_all_ops(struct unit_test_state *uts)
{
struct udevice *bus, *dev;
struct virtio_dev_priv *uc_priv;
uint offset = 0, len = 0, nvqs = 1;
void *buffer = NULL;
u8 status;
u32 counter;
u64 features;
struct virtqueue *vqs[2];
/* check probe success */
ut_assertok(uclass_first_device(UCLASS_VIRTIO, &bus));
ut_assertnonnull(bus);
/* check the child virtio-rng device is bound */
ut_assertok(device_find_first_child(bus, &dev));
ut_assertnonnull(dev);
/*
* fake the virtio device probe by filling in uc_priv->vdev
* which is used by virtio_find_vqs/virtio_del_vqs.
*/
uc_priv = dev_get_uclass_priv(bus);
ut_assertnonnull(uc_priv);
uc_priv->vdev = dev;
/* test virtio_xxx APIs */
ut_assertok(virtio_get_config(dev, offset, buffer, len));
ut_assertok(virtio_set_config(dev, offset, buffer, len));
ut_asserteq(-ENOSYS, virtio_generation(dev, &counter));
ut_assertok(virtio_set_status(dev, VIRTIO_CONFIG_S_DRIVER_OK));
ut_assertok(virtio_get_status(dev, &status));
ut_asserteq(VIRTIO_CONFIG_S_DRIVER_OK, status);
ut_assertok(virtio_reset(dev));
ut_assertok(virtio_get_status(dev, &status));
ut_asserteq(0, status);
ut_assertok(virtio_get_features(dev, &features));
ut_asserteq_64(BIT_ULL(VIRTIO_F_VERSION_1), features);
ut_assertok(virtio_set_features(dev));
ut_assertok(virtio_find_vqs(dev, nvqs, vqs));
ut_assertok(virtio_notify(dev, vqs[0]));
ut_assertok(virtio_del_vqs(dev));
return 0;
}
DM_TEST(dm_test_virtio_all_ops, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
/* Test removal of virtio device driver */
static int dm_test_virtio_remove(struct unit_test_state *uts)
{
struct udevice *bus, *dev;
/* check probe success */
ut_assertok(uclass_first_device(UCLASS_VIRTIO, &bus));
ut_assertnonnull(bus);
/* check the child virtio-rng device is bound */
ut_assertok(device_find_first_child(bus, &dev));
ut_assertnonnull(dev);
/* set driver status to VIRTIO_CONFIG_S_DRIVER_OK */
ut_assertok(virtio_set_status(dev, VIRTIO_CONFIG_S_DRIVER_OK));
/* check the device can be successfully removed */
dev_or_flags(dev, DM_FLAG_ACTIVATED);
ut_asserteq(-EKEYREJECTED, device_remove(bus, DM_REMOVE_ACTIVE_ALL));
ut_asserteq(false, device_active(dev));
return 0;
}
DM_TEST(dm_test_virtio_remove, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
/* Test all of the virtio ring */
static int dm_test_virtio_ring(struct unit_test_state *uts)
{
struct udevice *bus, *dev;
struct virtio_dev_priv *uc_priv;
struct virtqueue *vq;
struct virtio_sg sg[2];
struct virtio_sg *sgs[2];
unsigned int len;
u8 buffer[2][32];
/* check probe success */
ut_assertok(uclass_first_device(UCLASS_VIRTIO, &bus));
ut_assertnonnull(bus);
/* check the child virtio-blk device is bound */
ut_assertok(device_find_first_child(bus, &dev));
ut_assertnonnull(dev);
/*
* fake the virtio device probe by filling in uc_priv->vdev
* which is used by virtio_find_vqs/virtio_del_vqs.
*/
uc_priv = dev_get_uclass_priv(bus);
ut_assertnonnull(uc_priv);
uc_priv->vdev = dev;
/* prepare the scatter-gather buffer */
sg[0].addr = buffer[0];
sg[0].length = sizeof(buffer[0]);
sg[1].addr = buffer[1];
sg[1].length = sizeof(buffer[1]);
sgs[0] = &sg[0];
sgs[1] = &sg[1];
/* read a buffer and report written size from device */
ut_assertok(virtio_find_vqs(dev, 1, &vq));
ut_assertok(virtqueue_add(vq, sgs, 0, 1));
vq->vring.used->idx = 1;
vq->vring.used->ring[0].id = 0;
vq->vring.used->ring[0].len = 0x53355885;
ut_asserteq_ptr(buffer, virtqueue_get_buf(vq, &len));
ut_asserteq(0x53355885, len);
ut_assertok(virtio_del_vqs(dev));
/* rejects used descriptors that aren't a chain head */
ut_assertok(virtio_find_vqs(dev, 1, &vq));
ut_assertok(virtqueue_add(vq, sgs, 0, 2));
vq->vring.used->idx = 1;
vq->vring.used->ring[0].id = 1;
vq->vring.used->ring[0].len = 0x53355885;
ut_assertnull(virtqueue_get_buf(vq, &len));
ut_assertok(virtio_del_vqs(dev));
/* device changes to descriptor are ignored */
ut_assertok(virtio_find_vqs(dev, 1, &vq));
ut_assertok(virtqueue_add(vq, sgs, 0, 1));
vq->vring.desc[0].addr = cpu_to_virtio64(dev, 0xbadbad11);
vq->vring.desc[0].len = cpu_to_virtio32(dev, 0x11badbad);
vq->vring.desc[0].flags = cpu_to_virtio16(dev, VRING_DESC_F_NEXT);
vq->vring.desc[0].next = cpu_to_virtio16(dev, U16_MAX);
vq->vring.used->idx = 1;
vq->vring.used->ring[0].id = 0;
vq->vring.used->ring[0].len = 6;
ut_asserteq_ptr(buffer, virtqueue_get_buf(vq, &len));
ut_asserteq(6, len);
ut_assertok(virtio_del_vqs(dev));
return 0;
}
DM_TEST(dm_test_virtio_ring, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);

52
test/dm/virtio_rng.c Normal file
View File

@ -0,0 +1,52 @@
// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2022 Google, Inc.
* Written by Andrew Scull <ascull@google.com>
*/
#include <common.h>
#include <dm.h>
#include <virtio_types.h>
#include <virtio.h>
#include <virtio_ring.h>
#include <dm/device-internal.h>
#include <dm/test.h>
#include <rng.h>
#include <test/test.h>
#include <test/ut.h>
/* This is a brittle means of getting access to the virtqueue */
struct virtio_rng_priv {
struct virtqueue *rng_vq;
};
/* Test the virtio-rng driver validates the used size */
static int dm_test_virtio_rng_check_len(struct unit_test_state *uts)
{
struct udevice *bus, *dev;
struct virtio_rng_priv *priv;
u8 buffer[16];
/* check probe success */
ut_assertok(uclass_first_device(UCLASS_VIRTIO, &bus));
ut_assertnonnull(bus);
/* check the child virtio-rng device is bound */
ut_assertok(device_find_first_child(bus, &dev));
ut_assertnonnull(dev);
/* probe the virtio-rng driver */
ut_assertok(device_probe(dev));
/* simulate the device returning the buffer with too much data */
priv = dev_get_priv(dev);
priv->rng_vq->vring.used->idx = 1;
priv->rng_vq->vring.used->ring[0].id = 0;
priv->rng_vq->vring.used->ring[0].len = U32_MAX;
/* check the driver gracefully handles the error */
ut_asserteq(-EIO, dm_rng_read(dev, buffer, sizeof(buffer)));
return 0;
}
DM_TEST(dm_test_virtio_rng_check_len, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);