[PULL 17/17] docs/zoned-storage:add zoned emulation use case

[Stefan Hajnoczi <stefanha@redhat.com>]

From: Sam Li <faithilikerun@gmail.com>

Add the documentation about the example of using virtio-blk driver
to pass the zoned block devices through to the guest.

Signed-off-by: Sam Li <faithilikerun@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
[Fix rST syntax
--Stefan]
Message-Id: <20230407082528.18841-6-faithilikerun@gmail.com>
---
 docs/devel/zoned-storage.rst | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/docs/devel/zoned-storage.rst b/docs/devel/zoned-storage.rst
index da78db2783..e02500c8a3 100644
--- a/docs/devel/zoned-storage.rst
+++ b/docs/devel/zoned-storage.rst
@@ -41,3 +41,22 @@ APIs for zoned storage emulation or testing.
 For example, to test zone_report on a null_blk device using qemu-io is::
 
   $ path/to/qemu-io --image-opts -n driver=host_device,filename=/dev/nullb0 -c "zrp offset nr_zones"
+
+To expose the host's zoned block device through virtio-blk, the command line
+can be (includes the -device parameter)::
+
+  -blockdev node-name=drive0,driver=host_device,filename=/dev/nullb0,cache.direct=on \
+      -device virtio-blk-pci,drive=drive0
+
+Or only use the -drive parameter::
+
+  -driver driver=host_device,file=/dev/nullb0,if=virtio,cache.direct=on
+
+Additionally, QEMU has several ways of supporting zoned storage, including:
+(1) Using virtio-scsi: --device scsi-block allows for the passing through of
+SCSI ZBC devices, enabling the attachment of ZBC or ZAC HDDs to QEMU.
+(2) PCI device pass-through: While NVMe ZNS emulation is available for testing
+purposes, it cannot yet pass through a zoned device from the host. To pass on
+the NVMe ZNS device to the guest, use VFIO PCI pass the entire NVMe PCI adapter
+through to the guest. Likewise, an HDD HBA can be passed on to QEMU all HDDs
+attached to the HBA.
-- 
2.40.0