Bug 804924

Summary: qemu-kvm fails to hide a host device being written when passthrough it with usb-host
Product: Red Hat Enterprise Linux 6 Reporter: Shaolong Hu <shu>
Component: qemu-kvmAssignee: Virtualization Maintenance <virt-maint>
Status: CLOSED NOTABUG QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 6.3CC: acathrow, bsarathy, juzhang, kraxel, michen, mkenneth, virt-maint
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2012-03-20 08:48:55 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description Shaolong Hu 2012-03-20 08:11:30 UTC 
Description of problem:
------------------------
qemu-kvm fails to hide a host device being written when passthrough it with usb-host.

Version-Release number of selected component (if applicable):
--------------------------------------------------------------
qemu-kvm-0.12.1.2-2.249.el6.bz796118.1.x86_64
(i hit this when testing bz796118, i think in this case this build equals to 249)

How reproducible:
------------------
100%

Steps to Reproduce:
--------------------
1. plug two usb stick to host

2.[root@shu ~]# ls -il /dev/sd*
  6199 brw-rw----. 1 root disk 8,   0 Mar 20 22:01 /dev/sda
  6200 brw-rw----. 1 root disk 8,   1 Mar 20 22:01 /dev/sda1
  6201 brw-rw----. 1 root disk 8,   2 Mar 20 22:01 /dev/sda2
320354 brw-rw----. 1 root disk 8, 112 Mar 20 22:50 /dev/sdh
320520 brw-rw----. 1 root disk 8, 113 Mar 20 22:50 /dev/sdh1
320478 brw-rw----. 1 root disk 8, 128 Mar 20 22:50 /dev/sdi
320613 brw-rw----. 1 root disk 8, 129 Mar 20 22:50 /dev/sdi1

3. read from usb stick

[root@shu ~]# while true; do dd if=/dev/sdh1 of=/dev/null bs=1K count=1 &  dd if=/dev/sdi1 of=/dev/null bs=1K count=1 &  done

4. run qemu-kvm with "-device usb-host,hostbus=1,hostaddr=4,id=hostdev0 -device usb-host,hostbus=1,hostaddr=5,id=hostdev1"

5. [root@shu ~]# ls -il /dev/sd*
6199 brw-rw----. 1 root disk 8, 0 Mar 20 22:01 /dev/sda
6200 brw-rw----. 1 root disk 8, 1 Mar 20 22:01 /dev/sda1
6201 brw-rw----. 1 root disk 8, 2 Mar 20 22:01 /dev/sda2

6. at this time, dd will report open file error

7. by far all is expected, now let's write to the usb stick, then do 1-6:

 [root@shu ~]# ls -il /dev/sd*
  6199 brw-rw----. 1 root disk 8,   0 Mar 20 22:01 /dev/sda
  6200 brw-rw----. 1 root disk 8,   1 Mar 20 22:01 /dev/sda1
  6201 brw-rw----. 1 root disk 8,   2 Mar 20 22:01 /dev/sda2
262062 brw-rw----. 1 root disk 8, 112 Mar 20 22:44 /dev/sdh
262116 brw-rw----. 1 root disk 8, 113 Mar 20 22:47 /dev/sdh1
262171 brw-rw----. 1 root disk 8, 128 Mar 20 22:44 /dev/sdi
262224 brw-rw----. 1 root disk 8, 129 Mar 20 22:47 /dev/sdi1

9. [root@shu ~]# while true; do dd if=/dev/zero of=/dev/sdh1 bs=1K count=1 &  dd if=/dev/zero of=/dev/sdi1 bs=1K count=1 &  done

10. [root@shu ~]# ls -il /dev/sd*
  6199 brw-rw----. 1 root disk 8, 0 Mar 20 22:01 /dev/sda
  6200 brw-rw----. 1 root disk 8, 1 Mar 20 22:01 /dev/sda1
  6201 brw-rw----. 1 root disk 8, 2 Mar 20 22:01 /dev/sda2
297186 -rw-r--r--. 1 root root 1024 Mar 20 22:47 /dev/sdh1
297151 -rw-r--r--. 1 root root 1024 Mar 20 22:47 /dev/sdi1

11. now, /dev/sdh1 and /dev/sdi1 is reserved, but they are common file, and inode number changes, dd continues to write at this point, no error prompt.


Actual results:
----------------
fdisk -l in guest shows the two usb stick passthroughed, but i am not sure if they can be used correctly, for formatting a 16G usb stick on uchi may take forever.

Expected results:
-----------------
hide /dev/sdh1 and /dev/sdi1, writing to them shows error.
Comment 2 Shaolong Hu 2012-03-20 08:16:01 UTC 
in last comment, between step 9 and 10, should add one more step:
 
run qemu-kvm with "-device usb-host,hostbus=1,hostaddr=4,id=hostdev0 -device
usb-host,hostbus=1,hostaddr=5,id=hostdev1"


btw, when test this, with uchi only, no ehci.
Comment 3 Gerd Hoffmann 2012-03-20 08:48:55 UTC 
Everything works perfectly fine.  /dev/sdh1 and /dev/sdi1 go away.  dd creates a regular file then and writes to it.  Add "conv=nocreat" to the dd command line will make dd error out instead, which should fix your testcase.
Comment 4 Shaolong Hu 2012-03-20 08:57:59 UTC 
(In reply to comment #3)
> Everything works perfectly fine.  /dev/sdh1 and /dev/sdi1 go away.  dd creates
> a regular file then and writes to it.  Add "conv=nocreat" to the dd command
> line will make dd error out instead, which should fix your testcase.

Thanks for specifying~