10:29 a.m.
return -ENOBLURB;
Andrea Bolognani (2):
qemu: Invert condition nesting in qemuDomainDefValidate()
qemu: Enforce vCPU hotplug granularity constraints
src/qemu/qemu_domain.c | 56 +++++++++++++++++++---
tests/qemuxml2argvdata/cpu-hotplug-granularity.xml | 18 +++++++
tests/qemuxml2argvtest.c | 3 ++
3 files changed, 71 insertions(+), 6 deletions(-)
create mode 100644 tests/qemuxml2argvdata/cpu-hotplug-granularity.xml
--
2.14.3
10:29 a.m.
New subject: [libvirt] [PATCH 1/2] qemu: Invert condition nesting in qemuDomainDefValidate()
While at the moment we're only performing a single check that is
connected to vCPU hotplugging, we're going to introduce a second
one soon. Move the topology check underneath the capability check
to make that easier; as a bonus, doing so allows us to reduce the
scope of the 'topologycpus' variable.
Signed-off-by: Andrea Bolognani <abologna(a)redhat.com>
---
src/qemu/qemu_domain.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 74b82450b..e93333669 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -3299,7 +3299,6 @@ qemuDomainDefValidate(const virDomainDef *def,
{
virQEMUDriverPtr driver = opaque;
virQEMUCapsPtr qemuCaps = NULL;
- unsigned int topologycpus;
int ret = -1;
if (!(qemuCaps = virQEMUCapsCacheLookup(driver->qemuCapsCache,
@@ -3359,11 +3358,15 @@ qemuDomainDefValidate(const virDomainDef *def,
}
}
- /* qemu as of 2.5.0 rejects SMP topologies that don't match the cpu count */
- if (virDomainDefGetVcpusTopology(def, &topologycpus) == 0 &&
- topologycpus != virDomainDefGetVcpusMax(def)) {
- /* presence of query-hotpluggable-cpus should be a good enough witness */
- if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS)) {
+ /* QEMU 2.7 (detected via the availability of query-hotpluggable-cpus)
+ * enforces stricter rules than previous versions when it comes to guest
+ * CPU topology. Verify known constraints are respected */
+ if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS)) {
+ unsigned int topologycpus;
+
+ /* Max vCPU count and overall vCPU topology must agree */
+ if (virDomainDefGetVcpusTopology(def, &topologycpus) == 0 &&
+ topologycpus != virDomainDefGetVcpusMax(def)) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
_("CPU topology doesn't match maximum vcpu
count"));
goto cleanup;
--
2.14.3
6:18 a.m.
New subject: [libvirt] [PATCH 1/2] qemu: Invert condition nesting in qemuDomainDefValidate()
On Thu, Dec 14, 2017 at 17:29:50 +0100, Andrea Bolognani wrote:
While at the moment we're only performing a single check that is
connected to vCPU hotplugging, we're going to introduce a second
one soon. Move the topology check underneath the capability check
to make that easier; as a bonus, doing so allows us to reduce the
scope of the 'topologycpus' variable.
You know that generally we prefer variables declared at the top scope?
Also you change the version of qemu in the comment without explanation
here. Rather than bragging how you reduced scope, please document that
change.
Signed-off-by: Andrea Bolognani <abologna(a)redhat.com>
---
src/qemu/qemu_domain.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 74b82450b..e93333669 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -3299,7 +3299,6 @@ qemuDomainDefValidate(const virDomainDef *def,
{
virQEMUDriverPtr driver = opaque;
virQEMUCapsPtr qemuCaps = NULL;
- unsigned int topologycpus;
int ret = -1;
if (!(qemuCaps = virQEMUCapsCacheLookup(driver->qemuCapsCache,
@@ -3359,11 +3358,15 @@ qemuDomainDefValidate(const virDomainDef *def,
}
}
- /* qemu as of 2.5.0 rejects SMP topologies that don't match the cpu count */
- if (virDomainDefGetVcpusTopology(def, &topologycpus) == 0 &&
- topologycpus != virDomainDefGetVcpusMax(def)) {
- /* presence of query-hotpluggable-cpus should be a good enough witness */
- if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS)) {
+ /* QEMU 2.7 (detected via the availability of query-hotpluggable-cpus)
+ * enforces stricter rules than previous versions when it comes to guest
+ * CPU topology. Verify known constraints are respected */
+ if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS)) {
+ unsigned int topologycpus;
+
+ /* Max vCPU count and overall vCPU topology must agree */
+ if (virDomainDefGetVcpusTopology(def, &topologycpus) == 0 &&
+ topologycpus != virDomainDefGetVcpusMax(def)) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
_("CPU topology doesn't match maximum vcpu
count"));
goto cleanup;
The code looks okay, but I want to see a justification on the changed
version.
7:11 a.m.
New subject: [libvirt] [PATCH 1/2] qemu: Invert condition nesting in qemuDomainDefValidate()
On Fri, 2017-12-15 at 13:18 +0100, Peter Krempa wrote:
On Thu, Dec 14, 2017 at 17:29:50 +0100, Andrea Bolognani wrote:
> While at the moment we're only performing a single check that is
> connected to vCPU hotplugging, we're going to introduce a second
> one soon. Move the topology check underneath the capability check
> to make that easier; as a bonus, doing so allows us to reduce the
> scope of the 'topologycpus' variable.
You know that generally we prefer variables declared at the top scope?
Is that so? I've seen several instances of the opposite, and it
makes to me not to pollute the function scope with one-use
variables when there are usually enough variables that actually
need to be accessed throughout the function. But I can leave the
declaration where it is if you like it better that way.
Also you change the version of qemu in the comment without
explanation
here. Rather than bragging how you reduced scope, please document that
change.
Right, I meant to include the explanation but forgot :)
It's very simple, anyway: the version number was wrong, since
QEMU introduced query-hotpluggable-cpus in 2.7 rather than 2.5.
--
Andrea Bolognani / Red Hat / Virtualization
7:20 a.m.
New subject: [libvirt] [PATCH 1/2] qemu: Invert condition nesting in qemuDomainDefValidate()
On Fri, Dec 15, 2017 at 14:11:41 +0100, Andrea Bolognani wrote:
On Fri, 2017-12-15 at 13:18 +0100, Peter Krempa wrote:
> On Thu, Dec 14, 2017 at 17:29:50 +0100, Andrea Bolognani wrote:
> > While at the moment we're only performing a single check that is
> > connected to vCPU hotplugging, we're going to introduce a second
> > one soon. Move the topology check underneath the capability check
> > to make that easier; as a bonus, doing so allows us to reduce the
> > scope of the 'topologycpus' variable.
>
> You know that generally we prefer variables declared at the top scope?
Is that so? I've seen several instances of the opposite, and it
makes to me not to pollute the function scope with one-use
variables when there are usually enough variables that actually
need to be accessed throughout the function. But I can leave the
declaration where it is if you like it better that way.
Fair enough. We only state that we should declare it at the beginning of
a scope, so while generally most are declared at function scoep, this
does not violate the contributor guidelines.
> Also you change the version of qemu in the comment without explanation
> here. Rather than bragging how you reduced scope, please document that
> change.
Right, I meant to include the explanation but forgot :)
It's very simple, anyway: the version number was wrong, since
QEMU introduced query-hotpluggable-cpus in 2.7 rather than 2.5.
While this is true for the presence of query-hotpluggable-cpus. The
paragraph is specifically saying that QEMU rejects such configurations
starting from 2.5., but the code checks them only since
query-hotpluggable-cpus (which was introduced in 2.7).
Your modification is thus incorrect. You can add statement that
query-hotpluggable-cpus was added in 2.7. but mangling it as you did is
not correct in my opinion.
7:31 a.m.
New subject: [libvirt] [PATCH 1/2] qemu: Invert condition nesting in qemuDomainDefValidate()
On Fri, 2017-12-15 at 14:20 +0100, Peter Krempa wrote:
> > You know that generally we prefer variables declared at the
top scope?
>
> Is that so? I've seen several instances of the opposite, and it
> makes to me not to pollute the function scope with one-use
> variables when there are usually enough variables that actually
> need to be accessed throughout the function. But I can leave the
> declaration where it is if you like it better that way.
Fair enough. We only state that we should declare it at the beginning of
a scope, so while generally most are declared at function scoep, this
does not violate the contributor guidelines.
Cool, I'll still move it to the inner scope then.
> It's very simple, anyway: the version number was wrong,
since
> QEMU introduced query-hotpluggable-cpus in 2.7 rather than 2.5.
While this is true for the presence of query-hotpluggable-cpus. The
paragraph is specifically saying that QEMU rejects such configurations
starting from 2.5., but the code checks them only since
query-hotpluggable-cpus (which was introduced in 2.7).
Your modification is thus incorrect. You can add statement that
query-hotpluggable-cpus was added in 2.7. but mangling it as you did is
not correct in my opinion.
I see, that's a nuance I was not aware of. I'll amend the comment
so that it tells the whole story.
--
Andrea Bolognani / Red Hat / Virtualization
10:29 a.m.
New subject: [libvirt] [PATCH 2/2] qemu: Enforce vCPU hotplug granularity constraints
QEMU 2.7 and newer don't allow guests to start unless the initial
vCPUs count is a multiple of the vCPU hotplug granularity, so
validate it and report an error if needed.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1283700
Signed-off-by: Andrea Bolognani <abologna(a)redhat.com>
---
src/qemu/qemu_domain.c | 41 ++++++++++++++++++++++
tests/qemuxml2argvdata/cpu-hotplug-granularity.xml | 18 ++++++++++
tests/qemuxml2argvtest.c | 3 ++
3 files changed, 62 insertions(+)
create mode 100644 tests/qemuxml2argvdata/cpu-hotplug-granularity.xml
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index e93333669..632f330f7 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -3289,6 +3289,36 @@ qemuDomainDefValidateVideo(const virDomainDef *def)
}
+/**
+ * qemuDomainDefGetVcpuHotplugGranularity:
+ * @def: domain definition
+ * @granularity: return location for vCPU hotplug granularity
+ *
+ * With QEMU 2.7 and newer, vCPUs can only be hotplugged @granularity at
+ * a time; because of that, QEMU will not allow guests to start unless the
+ * initial number of vCPUs is a multiple of @granularity.
+ *
+ * Returns 0 on success, 1 if topology is not configured and -1 on error.
+ */
+static int
+qemuDomainDefGetVcpuHotplugGranularity(const virDomainDef *def,
+ unsigned int *granularity)
+{
+ if (!granularity)
+ return -1;
+
+ if (!def->cpu || def->cpu->sockets == 0)
+ return 1;
+
+ if (qemuDomainIsPSeries(def))
+ *granularity = def->cpu->threads;
+ else
+ *granularity = 1;
+
+ return 0;
+}
+
+
#define QEMU_MAX_VCPUS_WITHOUT_EIM 255
@@ -3363,6 +3393,7 @@ qemuDomainDefValidate(const virDomainDef *def,
* CPU topology. Verify known constraints are respected */
if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS)) {
unsigned int topologycpus;
+ unsigned int granularity;
/* Max vCPU count and overall vCPU topology must agree */
if (virDomainDefGetVcpusTopology(def, &topologycpus) == 0 &&
@@ -3371,6 +3402,16 @@ qemuDomainDefValidate(const virDomainDef *def,
_("CPU topology doesn't match maximum vcpu
count"));
goto cleanup;
}
+
+ /* vCPU hotplug granularity must be respected */
+ if (qemuDomainDefGetVcpuHotplugGranularity(def, &granularity) == 0
&&
+ (virDomainDefGetVcpus(def) % granularity) != 0) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+ _("vCPUs count must be a multiple of the vCPU "
+ "hotplug granularity (%u)"),
+ granularity);
+ goto cleanup;
+ }
}
if (ARCH_IS_X86(def->os.arch) &&
diff --git a/tests/qemuxml2argvdata/cpu-hotplug-granularity.xml
b/tests/qemuxml2argvdata/cpu-hotplug-granularity.xml
new file mode 100644
index 000000000..a94f41e46
--- /dev/null
+++ b/tests/qemuxml2argvdata/cpu-hotplug-granularity.xml
@@ -0,0 +1,18 @@
+<domain type='qemu'>
+ <name>guest</name>
+ <uuid>1ccfd97d-5eb4-478a-bbe6-88d254c16db7</uuid>
+ <memory unit='KiB'>524288</memory>
+ <vcpu placement='static' current='2'>8</vcpu>
+ <os>
+ <type arch='ppc64' machine='pseries'>hvm</type>
+ </os>
+ <cpu>
+ <topology sockets='1' cores='2' threads='4'/>
+ </cpu>
+ <devices>
+ <emulator>/usr/bin/qemu-system-ppc64</emulator>
+ <controller type='pci' model='pci-root'/>
+ <controller type='usb' model='none'/>
+ <memballoon model='none'/>
+ </devices>
+</domain>
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index ca24e0bbb..10ab8d787 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -2900,6 +2900,9 @@ mymain(void)
QEMU_CAPS_DEVICE_INTEL_IOMMU);
DO_TEST("cpu-hotplug-startup", QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS);
+ DO_TEST_PARSE_ERROR("cpu-hotplug-granularity",
+ QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS);
+
DO_TEST("virtio-options", QEMU_CAPS_VIRTIO_SCSI,
QEMU_CAPS_VIRTIO_KEYBOARD,
QEMU_CAPS_VIRTIO_MOUSE, QEMU_CAPS_VIRTIO_TABLET,
QEMU_CAPS_VIRTIO_INPUT_HOST,
--
2.14.3
6:22 a.m.
New subject: [libvirt] [PATCH 2/2] qemu: Enforce vCPU hotplug granularity constraints
On Thu, Dec 14, 2017 at 17:29:51 +0100, Andrea Bolognani wrote:
QEMU 2.7 and newer don't allow guests to start unless the
initial
vCPUs count is a multiple of the vCPU hotplug granularity, so
validate it and report an error if needed.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1283700
Signed-off-by: Andrea Bolognani <abologna(a)redhat.com>
---
src/qemu/qemu_domain.c | 41 ++++++++++++++++++++++
tests/qemuxml2argvdata/cpu-hotplug-granularity.xml | 18 ++++++++++
tests/qemuxml2argvtest.c | 3 ++
3 files changed, 62 insertions(+)
create mode 100644 tests/qemuxml2argvdata/cpu-hotplug-granularity.xml
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index e93333669..632f330f7 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -3289,6 +3289,36 @@ qemuDomainDefValidateVideo(const virDomainDef *def)
}
+/**
+ * qemuDomainDefGetVcpuHotplugGranularity:
+ * @def: domain definition
+ * @granularity: return location for vCPU hotplug granularity
+ *
+ * With QEMU 2.7 and newer, vCPUs can only be hotplugged @granularity at
+ * a time; because of that, QEMU will not allow guests to start unless the
+ * initial number of vCPUs is a multiple of @granularity.
+ *
+ * Returns 0 on success, 1 if topology is not configured and -1 on error.
+ */
+static int
+qemuDomainDefGetVcpuHotplugGranularity(const virDomainDef *def,
+ unsigned int *granularity)
+{
+ if (!granularity)
+ return -1;
Why?
+
+ if (!def->cpu || def->cpu->sockets == 0)
+ return 1;
I think we assume '1' as threads here if it's not specified.
+
+ if (qemuDomainIsPSeries(def))
+ *granularity = def->cpu->threads;
+ else
+ *granularity = 1;
Why not just return the granularity rather than this weirdness?
+
+ return 0;
+}
+
+
7:17 a.m.
New subject: [libvirt] [PATCH 2/2] qemu: Enforce vCPU hotplug granularity constraints
On Fri, 2017-12-15 at 13:22 +0100, Peter Krempa wrote:
> +
> + if (!def->cpu || def->cpu->sockets == 0)
> + return 1;
I think we assume '1' as threads here if it's not specified.
Okay.
> +
> + if (qemuDomainIsPSeries(def))
> + *granularity = def->cpu->threads;
> + else
> + *granularity = 1;
Why not just return the granularity rather than this weirdness?
Sure, I can do that.
Does the rest of the patch look reasonable, or do you want to
point out anything else before I respin?
--
Andrea Bolognani / Red Hat / Virtualization
2569
days inactive
2570
days old
8 comments
2 participants
participants (2)
-
Andrea Bolognani -
Peter Krempa