src/qemu/qemu_command.c | 9 +++++++++ tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml | 3 +++ 2 files changed, 12 insertions(+)
In order for memory locking to work, the hard limit on memory
locking (and usage) has to be set appropriately by the user.
The documentation mentions the requirement already: with this
patch, it's going to be enforced by runtime checks as well,
by forbidding a non-compliant guest from starting at all.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1316774
---
Changes from [v1]
* Address review feeback:
- check in BuildCommandLine rather than in PostParse,
so that non-compliant guests will merely fail to
start rather than disappear completely.
[v1] https://www.redhat.com/archives/libvir-list/2017-February/msg00180.html
src/qemu/qemu_command.c | 9 +++++++++
tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml | 3 +++
2 files changed, 12 insertions(+)
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 1396661..ca3bcdc 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -7340,6 +7340,15 @@ qemuBuildMemCommandLine(virCommandPtr cmd,
qemuBuildMemPathStr(cfg, def, qemuCaps, cmd) < 0)
return -1;
+ /* Memory locking can only work properly if the memory locking limit
+ * for the QEMU process has been raised appropriately: the default one
+ * is extrememly low, so there's no way the guest will fit in there */
+ if (def->mem.locked && !virMemoryLimitIsSet(def->mem.hard_limit)) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+ _("Setting <memoryBacking><locked> requires "
+ "<memtune><hard_limit> to be set as well"));
+ return -1;
+ }
if (def->mem.locked && !virQEMUCapsGet(qemuCaps, QEMU_CAPS_REALTIME_MLOCK)) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
_("memory locking not supported by QEMU binary"));
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml b/tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml
index 20a5eaa..2046663 100644
--- a/tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml
+++ b/tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml
@@ -3,6 +3,9 @@
<uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
<memory unit='KiB'>219136</memory>
<currentMemory unit='KiB'>219136</currentMemory>
+ <memtune>
+ <hard_limit unit='KiB'>256000</hard_limit>
+ </memtune>
<memoryBacking>
<locked/>
</memoryBacking>
--
2.7.4
--
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On Tue, Feb 07, 2017 at 12:35:03PM +0100, Andrea Bolognani wrote: > In order for memory locking to work, the hard limit on memory > locking (and usage) has to be set appropriately by the user. > > The documentation mentions the requirement already: with this > patch, it's going to be enforced by runtime checks as well, > by forbidding a non-compliant guest from starting at all. > > Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1316774 > --- > Changes from [v1] > > * Address review feeback: > - check in BuildCommandLine rather than in PostParse, > so that non-compliant guests will merely fail to > start rather than disappear completely. > > [v1] https://www.redhat.com/archives/libvir-list/2017-February/msg00180.html NACK, see my review for v1. This should be implemented in qemuDomainDefValidate. Pavel > > src/qemu/qemu_command.c | 9 +++++++++ > tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml | 3 +++ > 2 files changed, 12 insertions(+) > > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c > index 1396661..ca3bcdc 100644 > --- a/src/qemu/qemu_command.c > +++ b/src/qemu/qemu_command.c > @@ -7340,6 +7340,15 @@ qemuBuildMemCommandLine(virCommandPtr cmd, > qemuBuildMemPathStr(cfg, def, qemuCaps, cmd) < 0) > return -1; > > + /* Memory locking can only work properly if the memory locking limit > + * for the QEMU process has been raised appropriately: the default one > + * is extrememly low, so there's no way the guest will fit in there */ > + if (def->mem.locked && !virMemoryLimitIsSet(def->mem.hard_limit)) { > + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", > + _("Setting <memoryBacking><locked> requires " > + "<memtune><hard_limit> to be set as well")); > + return -1; > + } > if (def->mem.locked && !virQEMUCapsGet(qemuCaps, QEMU_CAPS_REALTIME_MLOCK)) { > virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", > _("memory locking not supported by QEMU binary")); > diff --git a/tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml b/tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml > index 20a5eaa..2046663 100644 > --- a/tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml > +++ b/tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml > @@ -3,6 +3,9 @@ > <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid> > <memory unit='KiB'>219136</memory> > <currentMemory unit='KiB'>219136</currentMemory> > + <memtune> > + <hard_limit unit='KiB'>256000</hard_limit> > + </memtune> > <memoryBacking> > <locked/> > </memoryBacking> > -- > 2.7.4 > > -- > libvir-list mailing list > libvir-list@redhat.com > https://www.redhat.com/mailman/listinfo/libvir-list -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
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