On 12/13/2012 12:05 PM, Osier Yang wrote:
Since "rawio" and "cdbfilter" are only valid for "lun", this groups them together; And since both of them intend to allow the unprivledged user to use the SG_IO commands, they must be
s/unprivledged/unprivileged/
exclusive. --- docs/formatdomain.html.in | 13 +++++++++- docs/schemas/domaincommon.rng | 52 ++++++++++++++++++++++++++++------------ 2 files changed, 48 insertions(+), 17 deletions(-)
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index 8e234fd..8c7c682 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -1395,7 +1395,18 @@ rawio='yes', rawio capability will be enabled for all disks in the domain (because, in the case of QEMU, this capability can only be set on a per-process basis). This attribute is only - valid when device is "lun". + valid when device is "lun". NB, <code>rawio</code> intends to + confine the capability per-device, however, current QEMU + implementation gives the domain process broader capability + than that (per-process basis, affects all the domain disks). + To confine the capability as much as possible for QEMU driver + as this stage, <code>cdbfilter</code> is recommended. + The optional <code>cdbfilter</code> attribute + (<span class="since">since 1.0.1</span>) indicates whether the + kernel will filter unprivileged SG_IO for the disk, valid settings + are "yes" or "no" (defaults to "yes"). Note that it's exclusive + with attribute <code>rawio</code>; Same with <code>rawio</code>, + <code>cdbfilter</code> is only valid for device 'lun'.
Hmm, this doesn't seem like the smartest of designs. If I'm understanding you right, we have: rawio cdbfilter result missing missing kernel prevents SG_IO missing no kernel prevents SG_IO missing yes SG_IO allowed for disk no missing kernel prevents SG_IO no no kernel prevents SG_IO no yes SG_IO allowed for disk yes missing SG_IO allowed for process yes no SG_IO allowed for process yes yes error Why not simplify things, and have a single attribute rawio, with multiple values? rawio result missing kernel prevents SG_IO no kernel prevents SG_IO yes SG_IO allowed for process cdb SG_IO allowed for disk where we document that 'yes' works on more kernel versions than 'cdb', but that 'cdb' (new to 1.0.1) is more secure.
The optional <code>snapshot</code> attribute indicates the default behavior of the disk during disk snapshots: "internal" requires a file format such as qcow2 that can store both the diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index 14344e2..c8cdfd7 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -971,24 +971,44 @@ --> <define name="disk"> <element name="disk"> - <optional> - <attribute name="device"> - <choice> - <value>floppy</value> - <value>disk</value> - <value>cdrom</value> - <value>lun</value> - </choice> - </attribute> - </optional> - <optional> - <attribute name="rawio"> + <choice> + <group> + <optional> + <attribute name="device"> + <choice> + <value>floppy</value> + <value>disk</value> + <value>cdrom</value> + </choice> + </attribute> + </optional> + </group>
I like that you split this up, to enforce that rawio only appears with device='lun'. However...
+ <group> + <optional> + <attribute name="device"> + <value>lun</value> + </attribute> + </optional>
This device='lun' should not be <optional>, since the default when device= is omitted is 'disk' (that is, unless you want the absence of device= and the presence of rawio='...' to imply a lun, but I think we should require an explicit use of lun before allowing rawio=).
<choice> - <value>yes</value> - <value>no</value> + <optional> + <attribute name="rawio"> + <choice> + <value>yes</value> + <value>no</value> + </choice> + </attribute> + </optional> + <optional> + <attribute name="cdbfilter"> + <choice> + <value>yes</value> + <value>no</value> + </choice>
And this part would need a major rework if you go with my idea of a tri-state attribute value for rawio instead of introducing yet another attribute.
+ </attribute> + </optional> </choice> - </attribute> - </optional> + </group> + </choice> <optional> <ref name="snapshot"/> </optional>
-- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org