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[PATCH v1 5/5] vhost-user-blk: dynamically resize config space based on
From: |
Daniil Tatianin |
Subject: |
[PATCH v1 5/5] vhost-user-blk: dynamically resize config space based on features |
Date: |
Wed, 24 Aug 2022 12:18:37 +0300 |
Make vhost-user-blk backwards compatible when migrating from older VMs
running with modern features turned off, the same way it was done for
virtio-blk in 20764be0421c ("virtio-blk: set config size depending on the
features enabled")
It's currently impossible to migrate from an older VM with
vhost-user-blk (with disable-legacy=off) because of errors like this:
qemu-system-x86_64: get_pci_config_device: Bad config data: i=0x10 read: 41
device: 1 cmask: ff wmask: 80 w1cmask:0
qemu-system-x86_64: Failed to load PCIDevice:config
qemu-system-x86_64: Failed to load virtio-blk:virtio
qemu-system-x86_64: error while loading state for instance 0x0 of device
'0000:00:05.0:00.0:02.0/virtio-blk'
qemu-system-x86_64: load of migration failed: Invalid argument
This is caused by the newer (destination) VM requiring a bigger BAR0
alignment because it has to cover a bigger configuration space, which
isn't actually needed since those additional config fields are not
active (write-zeroes/discard).
Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
---
hw/block/vhost-user-blk.c | 15 ++++++++-------
include/hw/virtio/vhost-user-blk.h | 1 +
2 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 64f3457373..d18a7a2cd4 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -23,6 +23,7 @@
#include "hw/qdev-core.h"
#include "hw/qdev-properties.h"
#include "hw/qdev-properties-system.h"
+#include "hw/virtio/virtio-blk-common.h"
#include "hw/virtio/vhost.h"
#include "hw/virtio/vhost-user-blk.h"
#include "hw/virtio/virtio.h"
@@ -63,7 +64,7 @@ static void vhost_user_blk_update_config(VirtIODevice *vdev,
uint8_t *config)
/* Our num_queues overrides the device backend */
virtio_stw_p(vdev, &s->blkcfg.num_queues, s->num_queues);
- memcpy(config, &s->blkcfg, sizeof(struct virtio_blk_config));
+ memcpy(config, &s->blkcfg, s->config_size);
}
static void vhost_user_blk_set_config(VirtIODevice *vdev, const uint8_t
*config)
@@ -96,8 +97,7 @@ static int vhost_user_blk_handle_config_change(struct
vhost_dev *dev)
Error *local_err = NULL;
ret = vhost_dev_get_config(dev, (uint8_t *)&blkcfg,
- sizeof(struct virtio_blk_config),
- &local_err);
+ s->config_size, &local_err);
if (ret < 0) {
error_report_err(local_err);
return ret;
@@ -106,7 +106,7 @@ static int vhost_user_blk_handle_config_change(struct
vhost_dev *dev)
/* valid for resize only */
if (blkcfg.capacity != s->blkcfg.capacity) {
s->blkcfg.capacity = blkcfg.capacity;
- memcpy(dev->vdev->config, &s->blkcfg, sizeof(struct
virtio_blk_config));
+ memcpy(dev->vdev->config, &s->blkcfg, s->config_size);
virtio_notify_config(dev->vdev);
}
@@ -444,7 +444,7 @@ static int vhost_user_blk_realize_connect(VHostUserBlk *s,
Error **errp)
assert(s->connected);
ret = vhost_dev_get_config(&s->dev, (uint8_t *)&s->blkcfg,
- sizeof(struct virtio_blk_config), errp);
+ s->config_size, errp);
if (ret < 0) {
qemu_chr_fe_disconnect(&s->chardev);
vhost_dev_cleanup(&s->dev);
@@ -489,8 +489,9 @@ static void vhost_user_blk_device_realize(DeviceState *dev,
Error **errp)
return;
}
- virtio_init(vdev, VIRTIO_ID_BLOCK,
- sizeof(struct virtio_blk_config));
+ s->config_size = virtio_blk_common_get_config_size(s->host_features);
+
+ virtio_init(vdev, VIRTIO_ID_BLOCK, s->config_size);
s->virtqs = g_new(VirtQueue *, s->num_queues);
for (i = 0; i < s->num_queues; i++) {
diff --git a/include/hw/virtio/vhost-user-blk.h
b/include/hw/virtio/vhost-user-blk.h
index 6252095c45..b7810360b9 100644
--- a/include/hw/virtio/vhost-user-blk.h
+++ b/include/hw/virtio/vhost-user-blk.h
@@ -52,6 +52,7 @@ struct VHostUserBlk {
bool started_vu;
uint64_t host_features;
+ size_t config_size;
};
#endif
--
2.25.1