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virtio-mem: Add support for suspend+wake-up with plugged memory 

Before, the virtio-mem device would unplug all the memory with any reset
of the device, including during the wake-up of the guest from a
suspended state. Due to this, the virtio-mem driver in the Linux kernel
disallowed suspend-to-ram requests in the guest when the
VIRTIO_MEM_F_PERSISTENT_SUSPEND feature is not exposed by QEMU.

This patch adds the code to skip the reset on wake-up and exposes
theVIRTIO_MEM_F_PERSISTENT_SUSPEND feature to the guest kernel driver
when suspending is possible in QEMU (currently only x86).

Message-ID: <20240904103722.946194-5-jmarcin@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Juraj Marcin <jmarcin@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
This commit is contained in:
Juraj Marcin 2024-09-04 12:37:15 +02:00 committed by David Hildenbrand
parent c009a311e9
commit 1f5f49056d
2 changed files with 13 additions and 0 deletions
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10
hw/virtio/virtio-mem.c
View File

@ -890,6 +890,9 @@ static uint64_t virtio_mem_get_features(VirtIODevice *vdev, uint64_t features,
if (vmem->unplugged_inaccessible == ON_OFF_AUTO_ON) {
virtio_add_feature(&features, VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE);
}
if (qemu_wakeup_suspend_enabled()) {
virtio_add_feature(&features, VIRTIO_MEM_F_PERSISTENT_SUSPEND);
}
return features;
}
@ -1848,6 +1851,13 @@ static void virtio_mem_system_reset_hold(Object *obj, ResetType type)
{
VirtIOMEM *vmem = VIRTIO_MEM(obj);
/*
* When waking up from standby/suspend-to-ram, do not unplug any memory.
*/
if (type == RESET_TYPE_WAKEUP) {
return;
}
/*
* During usual resets, we will unplug all memory and shrink the usable
* region size. This is, however, not possible in all scenarios. Then,

3
hw/virtio/virtio-qmp.c
View File

@ -450,6 +450,9 @@ static const qmp_virtio_feature_map_t virtio_mem_feature_map[] = {
FEATURE_ENTRY(VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE, \
"VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE: Unplugged memory cannot be "
"accessed"),
FEATURE_ENTRY(VIRTIO_MEM_F_PERSISTENT_SUSPEND, \
"VIRTIO_MEM_F_PERSISTENT_SUSPND: Plugged memory will remain "
"plugged when suspending+resuming"),
{ -1, "" }
};
#endif