Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Pull request

This includes the atomic_ -> qatomic_ rename that touches many files and is
prone to conflicts.

# gpg: Signature made Wed 23 Sep 2020 17:08:43 BST
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  qemu/atomic.h: rename atomic_ to qatomic_
  tests: add test-fdmon-epoll
  fdmon-poll: reset npfd when upgrading to fdmon-epoll
  gitmodules: add qemu.org vbootrom submodule
  gitmodules: switch to qemu.org meson mirror
  gitmodules: switch to qemu.org qboot mirror
  docs/system: clarify deprecation schedule
  virtio-crypto: don't modify elem->in/out_sg
  virtio-blk: undo destructive iov_discard_*() operations
  util/iov: add iov_discard_undo()
  virtio: add vhost-user-fs-ccw device
  libvhost-user: handle endianness as mandated by the spec
  MAINTAINERS: add Stefan Hajnoczi as block/nvme.c maintainer

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

12 files changed, 327 insertions, 84 deletions

diff --git a/tests/atomic64-bench.c b/tests/atomic64-bench.c
index 121a8c14f4..e474753d34 100644
--- a/tests/atomic64-bench.c
+++ b/tests/atomic64-bench.c
@@ -56,17 +56,17 @@ static void *thread_func(void *arg)
 {
     struct thread_info *info = arg;
 
-    atomic_inc(&n_ready_threads);
-    while (!atomic_read(&test_start)) {
+    qatomic_inc(&n_ready_threads);
+    while (!qatomic_read(&test_start)) {
         cpu_relax();
     }
 
-    while (!atomic_read(&test_stop)) {
+    while (!qatomic_read(&test_stop)) {
         unsigned int index;
 
         info->r = xorshift64star(info->r);
         index = info->r & (range - 1);
-        atomic_read_i64(&counts[index].i64);
+        qatomic_read_i64(&counts[index].i64);
         info->accesses++;
     }
     return NULL;
@@ -76,13 +76,13 @@ static void run_test(void)
 {
     unsigned int i;
 
-    while (atomic_read(&n_ready_threads) != n_threads) {
+    while (qatomic_read(&n_ready_threads) != n_threads) {
         cpu_relax();
     }
 
-    atomic_set(&test_start, true);
+    qatomic_set(&test_start, true);
     g_usleep(duration * G_USEC_PER_SEC);
-    atomic_set(&test_stop, true);
+    qatomic_set(&test_stop, true);
 
     for (i = 0; i < n_threads; i++) {
         qemu_thread_join(&threads[i]);
diff --git a/tests/atomic_add-bench.c b/tests/atomic_add-bench.c
index 5666f6bbff..f05471ab45 100644
--- a/tests/atomic_add-bench.c
+++ b/tests/atomic_add-bench.c
@@ -53,12 +53,12 @@ static void *thread_func(void *arg)
 {
     struct thread_info *info = arg;
 
-    atomic_inc(&n_ready_threads);
-    while (!atomic_read(&test_start)) {
+    qatomic_inc(&n_ready_threads);
+    while (!qatomic_read(&test_start)) {
         cpu_relax();
     }
 
-    while (!atomic_read(&test_stop)) {
+    while (!qatomic_read(&test_stop)) {
         unsigned int index;
 
         info->r = xorshift64star(info->r);
@@ -68,7 +68,7 @@ static void *thread_func(void *arg)
             counts[index].val += 1;
             qemu_mutex_unlock(&counts[index].lock);
         } else {
-            atomic_inc(&counts[index].val);
+            qatomic_inc(&counts[index].val);
         }
     }
     return NULL;
@@ -78,13 +78,13 @@ static void run_test(void)
 {
     unsigned int i;
 
-    while (atomic_read(&n_ready_threads) != n_threads) {
+    while (qatomic_read(&n_ready_threads) != n_threads) {
         cpu_relax();
     }
 
-    atomic_set(&test_start, true);
+    qatomic_set(&test_start, true);
     g_usleep(duration * G_USEC_PER_SEC);
-    atomic_set(&test_stop, true);
+    qatomic_set(&test_stop, true);
 
     for (i = 0; i < n_threads; i++) {
         qemu_thread_join(&threads[i]);
diff --git a/tests/iothread.c b/tests/iothread.c
index d3a2ee9a01..afde12b4ef 100644
--- a/tests/iothread.c
+++ b/tests/iothread.c
@@ -74,7 +74,7 @@ static void *iothread_run(void *opaque)
     qemu_cond_signal(&iothread->init_done_cond);
     qemu_mutex_unlock(&iothread->init_done_lock);
 
-    while (!atomic_read(&iothread->stopping)) {
+    while (!qatomic_read(&iothread->stopping)) {
         aio_poll(iothread->ctx, true);
     }
 
diff --git a/tests/meson.build b/tests/meson.build
index 8c3e930687..04072a64ca 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -170,6 +170,9 @@ if have_block
   if 'CONFIG_NETTLE' in config_host or 'CONFIG_GCRYPT' in config_host
     tests += {'test-crypto-pbkdf': [io]}
   endif
+  if 'CONFIG_EPOLL_CREATE1' in config_host
+    tests += {'test-fdmon-epoll': [testblock]}
+  endif
   benchs += {
      'benchmark-crypto-hash': [crypto],
      'benchmark-crypto-hmac': [crypto],
diff --git a/tests/qht-bench.c b/tests/qht-bench.c
index 362f03cb03..2e5b70ccd0 100644
--- a/tests/qht-bench.c
+++ b/tests/qht-bench.c
@@ -209,13 +209,13 @@ static void *thread_func(void *p)
 
     rcu_register_thread();
 
-    atomic_inc(&n_ready_threads);
-    while (!atomic_read(&test_start)) {
+    qatomic_inc(&n_ready_threads);
+    while (!qatomic_read(&test_start)) {
         cpu_relax();
     }
 
     rcu_read_lock();
-    while (!atomic_read(&test_stop)) {
+    while (!qatomic_read(&test_stop)) {
         info->seed = xorshift64star(info->seed);
         info->func(info);
     }
@@ -423,13 +423,13 @@ static void run_test(void)
 {
     int i;
 
-    while (atomic_read(&n_ready_threads) != n_rw_threads + n_rz_threads) {
+    while (qatomic_read(&n_ready_threads) != n_rw_threads + n_rz_threads) {
         cpu_relax();
     }
 
-    atomic_set(&test_start, true);
+    qatomic_set(&test_start, true);
     g_usleep(duration * G_USEC_PER_SEC);
-    atomic_set(&test_stop, true);
+    qatomic_set(&test_stop, true);
 
     for (i = 0; i < n_rw_threads; i++) {
         qemu_thread_join(&rw_threads[i]);
diff --git a/tests/rcutorture.c b/tests/rcutorture.c
index 732f03abda..de6f649058 100644
--- a/tests/rcutorture.c
+++ b/tests/rcutorture.c
@@ -123,7 +123,7 @@ static void *rcu_read_perf_test(void *arg)
     rcu_register_thread();
 
     *(struct rcu_reader_data **)arg = &rcu_reader;
-    atomic_inc(&nthreadsrunning);
+    qatomic_inc(&nthreadsrunning);
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
     }
@@ -149,7 +149,7 @@ static void *rcu_update_perf_test(void *arg)
     rcu_register_thread();
 
     *(struct rcu_reader_data **)arg = &rcu_reader;
-    atomic_inc(&nthreadsrunning);
+    qatomic_inc(&nthreadsrunning);
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
     }
@@ -172,7 +172,7 @@ static void perftestinit(void)
 
 static void perftestrun(int nthreads, int duration, int nreaders, int nupdaters)
 {
-    while (atomic_read(&nthreadsrunning) < nthreads) {
+    while (qatomic_read(&nthreadsrunning) < nthreads) {
         g_usleep(1000);
     }
     goflag = GOFLAG_RUN;
@@ -259,8 +259,8 @@ static void *rcu_read_stress_test(void *arg)
     }
     while (goflag == GOFLAG_RUN) {
         rcu_read_lock();
-        p = atomic_rcu_read(&rcu_stress_current);
-        if (atomic_read(&p->mbtest) == 0) {
+        p = qatomic_rcu_read(&rcu_stress_current);
+        if (qatomic_read(&p->mbtest) == 0) {
             n_mberror++;
         }
         rcu_read_lock();
@@ -268,7 +268,7 @@ static void *rcu_read_stress_test(void *arg)
             garbage++;
         }
         rcu_read_unlock();
-        pc = atomic_read(&p->age);
+        pc = qatomic_read(&p->age);
         rcu_read_unlock();
         if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0)) {
             pc = RCU_STRESS_PIPE_LEN;
@@ -301,7 +301,7 @@ static void *rcu_read_stress_test(void *arg)
 static void *rcu_update_stress_test(void *arg)
 {
     int i, rcu_stress_idx = 0;
-    struct rcu_stress *cp = atomic_read(&rcu_stress_current);
+    struct rcu_stress *cp = qatomic_read(&rcu_stress_current);
 
     rcu_register_thread();
     *(struct rcu_reader_data **)arg = &rcu_reader;
@@ -319,11 +319,11 @@ static void *rcu_update_stress_test(void *arg)
         p = &rcu_stress_array[rcu_stress_idx];
         /* catching up with ourselves would be a bug */
         assert(p != cp);
-        atomic_set(&p->mbtest, 0);
+        qatomic_set(&p->mbtest, 0);
         smp_mb();
-        atomic_set(&p->age, 0);
-        atomic_set(&p->mbtest, 1);
-        atomic_rcu_set(&rcu_stress_current, p);
+        qatomic_set(&p->age, 0);
+        qatomic_set(&p->mbtest, 1);
+        qatomic_rcu_set(&rcu_stress_current, p);
         cp = p;
         /*
          * New RCU structure is now live, update pipe counts on old
@@ -331,7 +331,7 @@ static void *rcu_update_stress_test(void *arg)
          */
         for (i = 0; i < RCU_STRESS_PIPE_LEN; i++) {
             if (i != rcu_stress_idx) {
-                atomic_set(&rcu_stress_array[i].age,
+                qatomic_set(&rcu_stress_array[i].age,
                            rcu_stress_array[i].age + 1);
             }
         }
diff --git a/tests/test-aio-multithread.c b/tests/test-aio-multithread.c
index d3144be7e0..a555cc8835 100644
--- a/tests/test-aio-multithread.c
+++ b/tests/test-aio-multithread.c
@@ -118,16 +118,16 @@ static bool schedule_next(int n)
 {
     Coroutine *co;
 
-    co = atomic_xchg(&to_schedule[n], NULL);
+    co = qatomic_xchg(&to_schedule[n], NULL);
     if (!co) {
-        atomic_inc(&count_retry);
+        qatomic_inc(&count_retry);
         return false;
     }
 
     if (n == id) {
-        atomic_inc(&count_here);
+        qatomic_inc(&count_here);
     } else {
-        atomic_inc(&count_other);
+        qatomic_inc(&count_other);
     }
 
     aio_co_schedule(ctx[n], co);
@@ -143,13 +143,13 @@ static coroutine_fn void test_multi_co_schedule_entry(void *opaque)
 {
     g_assert(to_schedule[id] == NULL);
 
-    while (!atomic_mb_read(&now_stopping)) {
+    while (!qatomic_mb_read(&now_stopping)) {
         int n;
 
         n = g_test_rand_int_range(0, NUM_CONTEXTS);
         schedule_next(n);
 
-        atomic_mb_set(&to_schedule[id], qemu_coroutine_self());
+        qatomic_mb_set(&to_schedule[id], qemu_coroutine_self());
         qemu_coroutine_yield();
         g_assert(to_schedule[id] == NULL);
     }
@@ -171,7 +171,7 @@ static void test_multi_co_schedule(int seconds)
 
     g_usleep(seconds * 1000000);
 
-    atomic_mb_set(&now_stopping, true);
+    qatomic_mb_set(&now_stopping, true);
     for (i = 0; i < NUM_CONTEXTS; i++) {
         ctx_run(i, finish_cb, NULL);
         to_schedule[i] = NULL;
@@ -202,7 +202,7 @@ static CoMutex comutex;
 
 static void coroutine_fn test_multi_co_mutex_entry(void *opaque)
 {
-    while (!atomic_mb_read(&now_stopping)) {
+    while (!qatomic_mb_read(&now_stopping)) {
         qemu_co_mutex_lock(&comutex);
         counter++;
         qemu_co_mutex_unlock(&comutex);
@@ -212,9 +212,9 @@ static void coroutine_fn test_multi_co_mutex_entry(void *opaque)
          * exits before the coroutine is woken up, causing a spurious
          * assertion failure.
          */
-        atomic_inc(&atomic_counter);
+        qatomic_inc(&atomic_counter);
     }
-    atomic_dec(&running);
+    qatomic_dec(&running);
 }
 
 static void test_multi_co_mutex(int threads, int seconds)
@@ -236,7 +236,7 @@ static void test_multi_co_mutex(int threads, int seconds)
 
     g_usleep(seconds * 1000000);
 
-    atomic_mb_set(&now_stopping, true);
+    qatomic_mb_set(&now_stopping, true);
     while (running > 0) {
         g_usleep(100000);
     }
@@ -296,9 +296,9 @@ static void mcs_mutex_lock(void)
 
     nodes[id].next = -1;
     nodes[id].locked = 1;
-    prev = atomic_xchg(&mutex_head, id);
+    prev = qatomic_xchg(&mutex_head, id);
     if (prev != -1) {
-        atomic_set(&nodes[prev].next, id);
+        qatomic_set(&nodes[prev].next, id);
         qemu_futex_wait(&nodes[id].locked, 1);
     }
 }
@@ -306,13 +306,13 @@ static void mcs_mutex_lock(void)
 static void mcs_mutex_unlock(void)
 {
     int next;
-    if (atomic_read(&nodes[id].next) == -1) {
-        if (atomic_read(&mutex_head) == id &&
-            atomic_cmpxchg(&mutex_head, id, -1) == id) {
+    if (qatomic_read(&nodes[id].next) == -1) {
+        if (qatomic_read(&mutex_head) == id &&
+            qatomic_cmpxchg(&mutex_head, id, -1) == id) {
             /* Last item in the list, exit.  */
             return;
         }
-        while (atomic_read(&nodes[id].next) == -1) {
+        while (qatomic_read(&nodes[id].next) == -1) {
             /* mcs_mutex_lock did the xchg, but has not updated
              * nodes[prev].next yet.
              */
@@ -320,20 +320,20 @@ static void mcs_mutex_unlock(void)
     }
 
     /* Wake up the next in line.  */
-    next = atomic_read(&nodes[id].next);
+    next = qatomic_read(&nodes[id].next);
     nodes[next].locked = 0;
     qemu_futex_wake(&nodes[next].locked, 1);
 }
 
 static void test_multi_fair_mutex_entry(void *opaque)
 {
-    while (!atomic_mb_read(&now_stopping)) {
+    while (!qatomic_mb_read(&now_stopping)) {
         mcs_mutex_lock();
         counter++;
         mcs_mutex_unlock();
-        atomic_inc(&atomic_counter);
+        qatomic_inc(&atomic_counter);
     }
-    atomic_dec(&running);
+    qatomic_dec(&running);
 }
 
 static void test_multi_fair_mutex(int threads, int seconds)
@@ -355,7 +355,7 @@ static void test_multi_fair_mutex(int threads, int seconds)
 
     g_usleep(seconds * 1000000);
 
-    atomic_mb_set(&now_stopping, true);
+    qatomic_mb_set(&now_stopping, true);
     while (running > 0) {
         g_usleep(100000);
     }
@@ -383,13 +383,13 @@ static QemuMutex mutex;
 
 static void test_multi_mutex_entry(void *opaque)
 {
-    while (!atomic_mb_read(&now_stopping)) {
+    while (!qatomic_mb_read(&now_stopping)) {
         qemu_mutex_lock(&mutex);
         counter++;
         qemu_mutex_unlock(&mutex);
-        atomic_inc(&atomic_counter);
+        qatomic_inc(&atomic_counter);
     }
-    atomic_dec(&running);
+    qatomic_dec(&running);
 }
 
 static void test_multi_mutex(int threads, int seconds)
@@ -411,7 +411,7 @@ static void test_multi_mutex(int threads, int seconds)
 
     g_usleep(seconds * 1000000);
 
-    atomic_mb_set(&now_stopping, true);
+    qatomic_mb_set(&now_stopping, true);
     while (running > 0) {
         g_usleep(100000);
     }
diff --git a/tests/test-fdmon-epoll.c b/tests/test-fdmon-epoll.c
new file mode 100644
index 0000000000..11fd8a2fa9
--- /dev/null
+++ b/tests/test-fdmon-epoll.c
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * fdmon-epoll tests
+ *
+ * Copyright (c) 2020 Red Hat, Inc.
+ */
+
+#include "qemu/osdep.h"
+#include "block/aio.h"
+#include "qapi/error.h"
+#include "qemu/main-loop.h"
+
+static AioContext *ctx;
+
+static void dummy_fd_handler(EventNotifier *notifier)
+{
+    event_notifier_test_and_clear(notifier);
+}
+
+static void add_event_notifiers(EventNotifier *notifiers, size_t n)
+{
+    for (size_t i = 0; i < n; i++) {
+        event_notifier_init(&notifiers[i], false);
+        aio_set_event_notifier(ctx, &notifiers[i], false,
+                               dummy_fd_handler, NULL);
+    }
+}
+
+static void remove_event_notifiers(EventNotifier *notifiers, size_t n)
+{
+    for (size_t i = 0; i < n; i++) {
+        aio_set_event_notifier(ctx, &notifiers[i], false, NULL, NULL);
+        event_notifier_cleanup(&notifiers[i]);
+    }
+}
+
+/* Check that fd handlers work when external clients are disabled */
+static void test_external_disabled(void)
+{
+    EventNotifier notifiers[100];
+
+    /* fdmon-epoll is only enabled when many fd handlers are registered */
+    add_event_notifiers(notifiers, G_N_ELEMENTS(notifiers));
+
+    event_notifier_set(&notifiers[0]);
+    assert(aio_poll(ctx, true));
+
+    aio_disable_external(ctx);
+    event_notifier_set(&notifiers[0]);
+    assert(aio_poll(ctx, true));
+    aio_enable_external(ctx);
+
+    remove_event_notifiers(notifiers, G_N_ELEMENTS(notifiers));
+}
+
+int main(int argc, char **argv)
+{
+    /*
+     * This code relies on the fact that fdmon-io_uring disables itself when
+     * the glib main loop is in use. The main loop uses fdmon-poll and upgrades
+     * to fdmon-epoll when the number of fds exceeds a threshold.
+     */
+    qemu_init_main_loop(&error_fatal);
+    ctx = qemu_get_aio_context();
+
+    while (g_main_context_iteration(NULL, false)) {
+        /* Do nothing */
+    }
+
+    g_test_init(&argc, &argv, NULL);
+    g_test_add_func("/fdmon-epoll/external-disabled", test_external_disabled);
+    return g_test_run();
+}
diff --git a/tests/test-iov.c b/tests/test-iov.c
index 458ca25099..9c415e2f1f 100644
--- a/tests/test-iov.c
+++ b/tests/test-iov.c
@@ -26,6 +26,12 @@ static void iov_free(struct iovec *iov, unsigned niov)
     g_free(iov);
 }
 
+static bool iov_equals(const struct iovec *a, const struct iovec *b,
+                       unsigned niov)
+{
+    return memcmp(a, b, sizeof(a[0]) * niov) == 0;
+}
+
 static void test_iov_bytes(struct iovec *iov, unsigned niov,
                            size_t offset, size_t bytes)
 {
@@ -335,6 +341,87 @@ static void test_discard_front(void)
     iov_free(iov, iov_cnt);
 }
 
+static void test_discard_front_undo(void)
+{
+    IOVDiscardUndo undo;
+    struct iovec *iov;
+    struct iovec *iov_tmp;
+    struct iovec *iov_orig;
+    unsigned int iov_cnt;
+    unsigned int iov_cnt_tmp;
+    size_t size;
+
+    /* Discard zero bytes */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_tmp = iov;
+    iov_cnt_tmp = iov_cnt;
+    iov_discard_front_undoable(&iov_tmp, &iov_cnt_tmp, 0, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+
+    /* Discard more bytes than vector size */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_tmp = iov;
+    iov_cnt_tmp = iov_cnt;
+    size = iov_size(iov, iov_cnt);
+    iov_discard_front_undoable(&iov_tmp, &iov_cnt_tmp, size + 1, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+
+    /* Discard entire vector */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_tmp = iov;
+    iov_cnt_tmp = iov_cnt;
+    size = iov_size(iov, iov_cnt);
+    iov_discard_front_undoable(&iov_tmp, &iov_cnt_tmp, size, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+
+    /* Discard within first element */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_tmp = iov;
+    iov_cnt_tmp = iov_cnt;
+    size = g_test_rand_int_range(1, iov->iov_len);
+    iov_discard_front_undoable(&iov_tmp, &iov_cnt_tmp, size, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+
+    /* Discard entire first element */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_tmp = iov;
+    iov_cnt_tmp = iov_cnt;
+    iov_discard_front_undoable(&iov_tmp, &iov_cnt_tmp, iov->iov_len, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+
+    /* Discard within second element */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_tmp = iov;
+    iov_cnt_tmp = iov_cnt;
+    size = iov->iov_len + g_test_rand_int_range(1, iov[1].iov_len);
+    iov_discard_front_undoable(&iov_tmp, &iov_cnt_tmp, size, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+}
+
 static void test_discard_back(void)
 {
     struct iovec *iov;
@@ -404,6 +491,82 @@ static void test_discard_back(void)
     iov_free(iov, iov_cnt);
 }
 
+static void test_discard_back_undo(void)
+{
+    IOVDiscardUndo undo;
+    struct iovec *iov;
+    struct iovec *iov_orig;
+    unsigned int iov_cnt;
+    unsigned int iov_cnt_tmp;
+    size_t size;
+
+    /* Discard zero bytes */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_cnt_tmp = iov_cnt;
+    iov_discard_back_undoable(iov, &iov_cnt_tmp, 0, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+
+    /* Discard more bytes than vector size */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_cnt_tmp = iov_cnt;
+    size = iov_size(iov, iov_cnt);
+    iov_discard_back_undoable(iov, &iov_cnt_tmp, size + 1, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+
+    /* Discard entire vector */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_cnt_tmp = iov_cnt;
+    size = iov_size(iov, iov_cnt);
+    iov_discard_back_undoable(iov, &iov_cnt_tmp, size, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+
+    /* Discard within last element */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_cnt_tmp = iov_cnt;
+    size = g_test_rand_int_range(1, iov[iov_cnt - 1].iov_len);
+    iov_discard_back_undoable(iov, &iov_cnt_tmp, size, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+
+    /* Discard entire last element */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_cnt_tmp = iov_cnt;
+    size = iov[iov_cnt - 1].iov_len;
+    iov_discard_back_undoable(iov, &iov_cnt_tmp, size, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+
+    /* Discard within second-to-last element */
+    iov_random(&iov, &iov_cnt);
+    iov_orig = g_memdup(iov, sizeof(iov[0]) * iov_cnt);
+    iov_cnt_tmp = iov_cnt;
+    size = iov[iov_cnt - 1].iov_len +
+           g_test_rand_int_range(1, iov[iov_cnt - 2].iov_len);
+    iov_discard_back_undoable(iov, &iov_cnt_tmp, size, &undo);
+    iov_discard_undo(&undo);
+    assert(iov_equals(iov, iov_orig, iov_cnt));
+    g_free(iov_orig);
+    iov_free(iov, iov_cnt);
+}
+
 int main(int argc, char **argv)
 {
     g_test_init(&argc, &argv, NULL);
@@ -412,5 +575,7 @@ int main(int argc, char **argv)
     g_test_add_func("/basic/iov/io", test_io);
     g_test_add_func("/basic/iov/discard-front", test_discard_front);
     g_test_add_func("/basic/iov/discard-back", test_discard_back);
+    g_test_add_func("/basic/iov/discard-front-undo", test_discard_front_undo);
+    g_test_add_func("/basic/iov/discard-back-undo", test_discard_back_undo);
     return g_test_run();
 }
diff --git a/tests/test-logging.c b/tests/test-logging.c
index 8b1522cfed..ccb819f193 100644
--- a/tests/test-logging.c
+++ b/tests/test-logging.c
@@ -133,7 +133,7 @@ static void test_logfile_write(gconstpointer data)
      */
     qemu_set_log_filename(file_path, &error_abort);
     rcu_read_lock();
-    logfile = atomic_rcu_read(&qemu_logfile);
+    logfile = qatomic_rcu_read(&qemu_logfile);
     orig_fd = logfile->fd;
     g_assert(logfile && logfile->fd);
     fprintf(logfile->fd, "%s 1st write to file\n", __func__);
@@ -141,7 +141,7 @@ static void test_logfile_write(gconstpointer data)
 
     /* Change the logfile and ensure that the handle is still valid. */
     qemu_set_log_filename(file_path1, &error_abort);
-    logfile2 = atomic_rcu_read(&qemu_logfile);
+    logfile2 = qatomic_rcu_read(&qemu_logfile);
     g_assert(logfile->fd == orig_fd);
     g_assert(logfile2->fd != logfile->fd);
     fprintf(logfile->fd, "%s 2nd write to file\n", __func__);
diff --git a/tests/test-rcu-list.c b/tests/test-rcu-list.c
index 92be51ec50..49641e1936 100644
--- a/tests/test-rcu-list.c
+++ b/tests/test-rcu-list.c
@@ -106,7 +106,7 @@ static void reclaim_list_el(struct rcu_head *prcu)
     struct list_element *el = container_of(prcu, struct list_element, rcu);
     g_free(el);
     /* Accessed only from call_rcu thread.  */
-    atomic_set_i64(&n_reclaims, n_reclaims + 1);
+    qatomic_set_i64(&n_reclaims, n_reclaims + 1);
 }
 
 #if TEST_LIST_TYPE == 1
@@ -172,16 +172,16 @@ static void *rcu_q_reader(void *arg)
     rcu_register_thread();
 
     *(struct rcu_reader_data **)arg = &rcu_reader;
-    atomic_inc(&nthreadsrunning);
-    while (atomic_read(&goflag) == GOFLAG_INIT) {
+    qatomic_inc(&nthreadsrunning);
+    while (qatomic_read(&goflag) == GOFLAG_INIT) {
         g_usleep(1000);
     }
 
-    while (atomic_read(&goflag) == GOFLAG_RUN) {
+    while (qatomic_read(&goflag) == GOFLAG_RUN) {
         rcu_read_lock();
         TEST_LIST_FOREACH_RCU(el, &Q_list_head, entry) {
             n_reads_local++;
-            if (atomic_read(&goflag) == GOFLAG_STOP) {
+            if (qatomic_read(&goflag) == GOFLAG_STOP) {
                 break;
             }
         }
@@ -207,12 +207,12 @@ static void *rcu_q_updater(void *arg)
     struct list_element *el, *prev_el;
 
     *(struct rcu_reader_data **)arg = &rcu_reader;
-    atomic_inc(&nthreadsrunning);
-    while (atomic_read(&goflag) == GOFLAG_INIT) {
+    qatomic_inc(&nthreadsrunning);
+    while (qatomic_read(&goflag) == GOFLAG_INIT) {
         g_usleep(1000);
     }
 
-    while (atomic_read(&goflag) == GOFLAG_RUN) {
+    while (qatomic_read(&goflag) == GOFLAG_RUN) {
         target_el = select_random_el(RCU_Q_LEN);
         j = 0;
         /* FOREACH_RCU could work here but let's use both macros */
@@ -226,7 +226,7 @@ static void *rcu_q_updater(void *arg)
                 break;
             }
         }
-        if (atomic_read(&goflag) == GOFLAG_STOP) {
+        if (qatomic_read(&goflag) == GOFLAG_STOP) {
             break;
         }
         target_el = select_random_el(RCU_Q_LEN);
@@ -248,7 +248,7 @@ static void *rcu_q_updater(void *arg)
     qemu_mutex_lock(&counts_mutex);
     n_nodes += n_nodes_local;
     n_updates += n_updates_local;
-    atomic_set_i64(&n_nodes_removed, n_nodes_removed + n_removed_local);
+    qatomic_set_i64(&n_nodes_removed, n_nodes_removed + n_removed_local);
     qemu_mutex_unlock(&counts_mutex);
     return NULL;
 }
@@ -271,13 +271,13 @@ static void rcu_qtest_init(void)
 static void rcu_qtest_run(int duration, int nreaders)
 {
     int nthreads = nreaders + 1;
-    while (atomic_read(&nthreadsrunning) < nthreads) {
+    while (qatomic_read(&nthreadsrunning) < nthreads) {
         g_usleep(1000);
     }
 
-    atomic_set(&goflag, GOFLAG_RUN);
+    qatomic_set(&goflag, GOFLAG_RUN);
     sleep(duration);
-    atomic_set(&goflag, GOFLAG_STOP);
+    qatomic_set(&goflag, GOFLAG_STOP);
     wait_all_threads();
 }
 
@@ -302,21 +302,23 @@ static void rcu_qtest(const char *test, int duration, int nreaders)
         n_removed_local++;
     }
     qemu_mutex_lock(&counts_mutex);
-    atomic_set_i64(&n_nodes_removed, n_nodes_removed + n_removed_local);
+    qatomic_set_i64(&n_nodes_removed, n_nodes_removed + n_removed_local);
     qemu_mutex_unlock(&counts_mutex);
     synchronize_rcu();
-    while (atomic_read_i64(&n_nodes_removed) > atomic_read_i64(&n_reclaims)) {
+    while (qatomic_read_i64(&n_nodes_removed) >
+           qatomic_read_i64(&n_reclaims)) {
         g_usleep(100);
         synchronize_rcu();
     }
     if (g_test_in_charge) {
-        g_assert_cmpint(atomic_read_i64(&n_nodes_removed), ==,
-                        atomic_read_i64(&n_reclaims));
+        g_assert_cmpint(qatomic_read_i64(&n_nodes_removed), ==,
+                        qatomic_read_i64(&n_reclaims));
     } else {
         printf("%s: %d readers; 1 updater; nodes read: "  \
                "%lld, nodes removed: %"PRIi64"; nodes reclaimed: %"PRIi64"\n",
                test, nthreadsrunning - 1, n_reads,
-               atomic_read_i64(&n_nodes_removed), atomic_read_i64(&n_reclaims));
+               qatomic_read_i64(&n_nodes_removed),
+               qatomic_read_i64(&n_reclaims));
         exit(0);
     }
 }
diff --git a/tests/test-thread-pool.c b/tests/test-thread-pool.c
index 0b675923f6..70dc6314a1 100644
--- a/tests/test-thread-pool.c
+++ b/tests/test-thread-pool.c
@@ -21,15 +21,15 @@ typedef struct {
 static int worker_cb(void *opaque)
 {
     WorkerTestData *data = opaque;
-    return atomic_fetch_inc(&data->n);
+    return qatomic_fetch_inc(&data->n);
 }
 
 static int long_cb(void *opaque)
 {
     WorkerTestData *data = opaque;
-    if (atomic_cmpxchg(&data->n, 0, 1) == 0) {
+    if (qatomic_cmpxchg(&data->n, 0, 1) == 0) {
         g_usleep(2000000);
-        atomic_or(&data->n, 2);
+        qatomic_or(&data->n, 2);
     }
     return 0;
 }
@@ -172,7 +172,7 @@ static void do_test_cancel(bool sync)
     /* Cancel the jobs that haven't been started yet.  */
     num_canceled = 0;
     for (i = 0; i < 100; i++) {
-        if (atomic_cmpxchg(&data[i].n, 0, 4) == 0) {
+        if (qatomic_cmpxchg(&data[i].n, 0, 4) == 0) {
             data[i].ret = -ECANCELED;
             if (sync) {
                 bdrv_aio_cancel(data[i].aiocb);
@@ -186,7 +186,7 @@ static void do_test_cancel(bool sync)
     g_assert_cmpint(num_canceled, <, 100);
 
     for (i = 0; i < 100; i++) {
-        if (data[i].aiocb && atomic_read(&data[i].n) < 4) {
+        if (data[i].aiocb && qatomic_read(&data[i].n) < 4) {
             if (sync) {
                 /* Canceling the others will be a blocking operation.  */
                 bdrv_aio_cancel(data[i].aiocb);