Currently, attaching zoned block devices (i.e., storage devices compliant to ZAC/ZBC standards) using several virtio methods doesn't work properly as zoned devices appear as regular block devices at the guest. This may cause unexpected i/o errors and, potentially, some data corruption.
To be more precise, attaching a zoned device via virtio-pci-blk, virtio-scsi-pci/scsi-disk or virtio-scsi-pci/scsi-hd demonstrates the above behavior. The virtio-scsi-pci/scsi-block method works with a recent patch. The virtio-scsi-pci/scsi-generic method also appears to handle zoned devices without problems. This patch set adds code to check if the backing device that is being opened is a zoned Host Managed device. If this is the case, the patch prohibits attaching such device for all use cases lacking proper zoned support. Host Aware zoned block devices are designed to work as regular block devices at a guest system that does not support ZBD. Therefore, this patch set doesn't prohibit attachment of Host Aware devices. Considering that there is still a couple of different working ways to attach a ZBD, this patch set provides a reasonable short-term solution for this problem. What about long term? It appears to be beneficial to add proper ZBD support to virtio-blk. In order to support this use case properly, some virtio-blk protocol changes will be necessary. They are needed to allow the host code to propagate some ZBD properties that are required for virtio guest driver to configure the guest block device as ZBD, such as zoned device model, zone size and the total number of zones. Further, some support needs to be added for REPORT ZONES command as well as for zone operations, such as OPEN ZONE, CLOSE ZONE, FINISH ZONE and RESET ZONE. These additions to the protocol are relatively straightforward, but they need to be approved by the virtio TC and the whole process may take some time. ZBD support for virtio-scsi-pci/scsi-disk and virtio-scsi-pci/scsi-hd does not seem as necessary. Users will be expected to attach zoned block devices via virtio-scsi-pci/scsi-block instead. This patch set contains some Linux-specific code. This code is necessary to obtain Zoned Block Device model value from Linux sysfs. History: v1 -> v2: - rework the code to be permission-based - always allow Host Aware devices to be attached - add fix for Host Aware attachments aka RCAP output snoop v2 -> v3: - drop the patch for RCAP output snoop - merged separately Dmitry Fomichev (4): block: Add zoned device model property raw: Recognize zoned backing devices block/ide/scsi: Set BLK_PERM_SUPPORT_ZONED raw: Don't open ZBDs if backend can't handle them block.c | 19 +++++++++ block/file-posix.c | 88 +++++++++++++++++++++++++++++++++------ block/raw-format.c | 8 ++++ hw/block/block.c | 8 +++- hw/block/fdc.c | 4 +- hw/block/nvme.c | 2 +- hw/block/virtio-blk.c | 2 +- hw/block/xen-block.c | 2 +- hw/ide/qdev.c | 2 +- hw/scsi/scsi-disk.c | 13 +++--- hw/scsi/scsi-generic.c | 2 +- hw/usb/dev-storage.c | 2 +- include/block/block.h | 21 +++++++++- include/block/block_int.h | 4 ++ include/hw/block/block.h | 3 +- 15 files changed, 150 insertions(+), 30 deletions(-) -- 2.21.0