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qemu-kvm/SOURCES/kvm-virtio-Drop-out-of-coro...

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From b99a7e5e5631af3ee806fd0d78d7c7056eb559b5 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Tue, 5 Sep 2023 16:50:02 +0200
Subject: [PATCH] virtio: Drop out of coroutine context in virtio_load()
RH-Author: Kevin Wolf <kwolf@redhat.com>
RH-MergeRequest: 319: virtio: Drop out of coroutine context in virtio_load() [9.3.0.z 0day]
RH-Jira: RHEL-4453
RH-Acked-by: Hanna Czenczek <hreitz@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Commit: [1/1] 6ae1d5a464e27bfaf892e093febcaf211a1ff5ec
virtio_load() as a whole should run in coroutine context because it
reads from the migration stream and we don't want this to block.
However, it calls virtio_set_features_nocheck() and devices don't
expect their .set_features callback to run in a coroutine and therefore
call functions that may not be called in coroutine context. To fix this,
drop out of coroutine context for calling virtio_set_features_nocheck().
Without this fix, the following crash was reported:
#0 __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
#1 0x00007efc738c05d3 in __pthread_kill_internal (signo=6, threadid=<optimized out>) at pthread_kill.c:78
#2 0x00007efc73873d26 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#3 0x00007efc738477f3 in __GI_abort () at abort.c:79
#4 0x00007efc7384771b in __assert_fail_base (fmt=0x7efc739dbcb8 "", assertion=assertion@entry=0x560aebfbf5cf "!qemu_in_coroutine()",
file=file@entry=0x560aebfcd2d4 "../block/graph-lock.c", line=line@entry=275, function=function@entry=0x560aebfcd34d "void bdrv_graph_rdlock_main_loop(void)") at assert.c:92
#5 0x00007efc7386ccc6 in __assert_fail (assertion=0x560aebfbf5cf "!qemu_in_coroutine()", file=0x560aebfcd2d4 "../block/graph-lock.c", line=275,
function=0x560aebfcd34d "void bdrv_graph_rdlock_main_loop(void)") at assert.c:101
#6 0x0000560aebcd8dd6 in bdrv_register_buf ()
#7 0x0000560aeb97ed97 in ram_block_added.llvm ()
#8 0x0000560aebb8303f in ram_block_add.llvm ()
#9 0x0000560aebb834fa in qemu_ram_alloc_internal.llvm ()
#10 0x0000560aebb2ac98 in vfio_region_mmap ()
#11 0x0000560aebb3ea0f in vfio_bars_register ()
#12 0x0000560aebb3c628 in vfio_realize ()
#13 0x0000560aeb90f0c2 in pci_qdev_realize ()
#14 0x0000560aebc40305 in device_set_realized ()
#15 0x0000560aebc48e07 in property_set_bool.llvm ()
#16 0x0000560aebc46582 in object_property_set ()
#17 0x0000560aebc4cd58 in object_property_set_qobject ()
#18 0x0000560aebc46ba7 in object_property_set_bool ()
#19 0x0000560aeb98b3ca in qdev_device_add_from_qdict ()
#20 0x0000560aebb1fbaf in virtio_net_set_features ()
#21 0x0000560aebb46b51 in virtio_set_features_nocheck ()
#22 0x0000560aebb47107 in virtio_load ()
#23 0x0000560aeb9ae7ce in vmstate_load_state ()
#24 0x0000560aeb9d2ee9 in qemu_loadvm_state_main ()
#25 0x0000560aeb9d45e1 in qemu_loadvm_state ()
#26 0x0000560aeb9bc32c in process_incoming_migration_co.llvm ()
#27 0x0000560aebeace56 in coroutine_trampoline.llvm ()
Cc: qemu-stable@nongnu.org
Buglink: https://issues.redhat.com/browse/RHEL-832
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230905145002.46391-3-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 92e2e6a867334a990f8d29f07ca34e3162fdd6ec)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
hw/virtio/virtio.c | 45 ++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 40 insertions(+), 5 deletions(-)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 98c4819fcc..0010a9a5f1 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2825,8 +2825,9 @@ static int virtio_device_put(QEMUFile *f, void *opaque, size_t size,
}
/* A wrapper for use as a VMState .get function */
-static int virtio_device_get(QEMUFile *f, void *opaque, size_t size,
- const VMStateField *field)
+static int coroutine_mixed_fn
+virtio_device_get(QEMUFile *f, void *opaque, size_t size,
+ const VMStateField *field)
{
VirtIODevice *vdev = VIRTIO_DEVICE(opaque);
DeviceClass *dc = DEVICE_CLASS(VIRTIO_DEVICE_GET_CLASS(vdev));
@@ -2853,6 +2854,39 @@ static int virtio_set_features_nocheck(VirtIODevice *vdev, uint64_t val)
return bad ? -1 : 0;
}
+typedef struct VirtioSetFeaturesNocheckData {
+ Coroutine *co;
+ VirtIODevice *vdev;
+ uint64_t val;
+ int ret;
+} VirtioSetFeaturesNocheckData;
+
+static void virtio_set_features_nocheck_bh(void *opaque)
+{
+ VirtioSetFeaturesNocheckData *data = opaque;
+
+ data->ret = virtio_set_features_nocheck(data->vdev, data->val);
+ aio_co_wake(data->co);
+}
+
+static int coroutine_mixed_fn
+virtio_set_features_nocheck_maybe_co(VirtIODevice *vdev, uint64_t val)
+{
+ if (qemu_in_coroutine()) {
+ VirtioSetFeaturesNocheckData data = {
+ .co = qemu_coroutine_self(),
+ .vdev = vdev,
+ .val = val,
+ };
+ aio_bh_schedule_oneshot(qemu_get_current_aio_context(),
+ virtio_set_features_nocheck_bh, &data);
+ qemu_coroutine_yield();
+ return data.ret;
+ } else {
+ return virtio_set_features_nocheck(vdev, val);
+ }
+}
+
int virtio_set_features(VirtIODevice *vdev, uint64_t val)
{
int ret;
@@ -2906,7 +2940,8 @@ size_t virtio_get_config_size(const VirtIOConfigSizeParams *params,
return config_size;
}
-int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
+int coroutine_mixed_fn
+virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
{
int i, ret;
int32_t config_len;
@@ -3023,14 +3058,14 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
* host_features.
*/
uint64_t features64 = vdev->guest_features;
- if (virtio_set_features_nocheck(vdev, features64) < 0) {
+ if (virtio_set_features_nocheck_maybe_co(vdev, features64) < 0) {
error_report("Features 0x%" PRIx64 " unsupported. "
"Allowed features: 0x%" PRIx64,
features64, vdev->host_features);
return -1;
}
} else {
- if (virtio_set_features_nocheck(vdev, features) < 0) {
+ if (virtio_set_features_nocheck_maybe_co(vdev, features) < 0) {
error_report("Features 0x%x unsupported. "
"Allowed features: 0x%" PRIx64,
features, vdev->host_features);
--
2.39.3
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