153 lines
6.5 KiB
Diff
153 lines
6.5 KiB
Diff
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From de94232ffb9eef84bb72631979f59bbadfc3cb9e Mon Sep 17 00:00:00 2001
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Message-ID: <de94232ffb9eef84bb72631979f59bbadfc3cb9e.1707394626.git.jdenemar@redhat.com>
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From: Michal Privoznik <mprivozn@redhat.com>
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Date: Thu, 4 Jan 2024 10:03:36 +0100
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Subject: [PATCH] conf: Introduce dynamicMemslots attribute for virtio-mem
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Introduced in v8.2.0-rc0~74^2~2, QEMU now allows setting
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.dynamic-memslots attribute for virtio-mem-pci devices. When
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turned on, it allows memory exposed to guest to be split into
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multiple memslots and thus smaller memory footprint (see the
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original commit for detailed explanation).
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Therefore, introduce new <target/> attribute which will control
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that QEMU knob.
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Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
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Reviewed-by: Peter Krempa <pkrempa@redhat.com>
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(cherry picked from commit 53258205854e649bc82310542373df004a4734ab)
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Resolves: https://issues.redhat.com/browse/RHEL-15316
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Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
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---
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docs/formatdomain.rst | 13 +++++++++++++
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src/conf/domain_conf.c | 18 +++++++++++++++++-
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src/conf/domain_conf.h | 1 +
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src/conf/schemas/domaincommon.rng | 5 +++++
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.../memory-hotplug-virtio-mem.xml | 2 +-
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5 files changed, 37 insertions(+), 2 deletions(-)
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diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
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index 298ad46a45..34b2564909 100644
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--- a/docs/formatdomain.rst
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+++ b/docs/formatdomain.rst
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@@ -8437,6 +8437,19 @@ Example: usage of the memory devices
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The ``node`` subelement configures the guest NUMA node to attach the memory
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to. The element shall be used only if the guest has NUMA nodes configured.
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+ For ``virtio-mem`` optional attribute ``dynamicMemslots`` can be specified
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+ (accepted values "yes"/"no") which allows hypervisor to spread memory into
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+ multiple memory slots (allocate them dynamically based on the amount of
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+ memory exposed to the guest), resulting in smaller memory footprint. But be
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+ aware this may affect vhost-user devices. When enabled, older vhost-user
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+ device implementations (such as virtiofs) may refuse to initialize resulting
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+ in failed domain startup or device hotplug. When only modern vhost-user
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+ based devices will be used or when no vhost-user devices are expected to be
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+ used it's beneficial to enable this feature. The current default is
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+ hypervisor dependant (for QEMU is "no"). If the default changes and you are
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+ having difficulties with vhost-user devices, try toggling this to "no".
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+ :since:`Since 10.1.0 and QEMU 8.2.0`
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+
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The following optional elements may be used:
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``label``
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diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
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index 6211d2a51b..ac06fa39f6 100644
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--- a/src/conf/domain_conf.c
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+++ b/src/conf/domain_conf.c
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@@ -13543,6 +13543,10 @@ virDomainMemoryTargetDefParseXML(xmlNodePtr node,
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&def->target.virtio_mem.requestedsize, false, false) < 0)
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return -1;
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+ if (virXMLPropTristateBool(node, "dynamicMemslots", VIR_XML_PROP_NONE,
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+ &def->target.virtio_mem.dynamicMemslots) < 0)
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+ return -1;
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+
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addrNode = virXPathNode("./address", ctxt);
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addr = &def->target.virtio_mem.address;
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break;
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@@ -21217,6 +21221,12 @@ virDomainMemoryDefCheckABIStability(virDomainMemoryDef *src,
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src->target.virtio_mem.address);
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return false;
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}
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+
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+ if (src->target.virtio_mem.dynamicMemslots != dst->target.virtio_mem.dynamicMemslots) {
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+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
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+ _("Target memory device 'dynamicMemslots' property doesn't match source memory device"));
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+ return false;
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+ }
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break;
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case VIR_DOMAIN_MEMORY_MODEL_DIMM:
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@@ -25432,6 +25442,7 @@ virDomainMemoryTargetDefFormat(virBuffer *buf,
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unsigned int flags)
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{
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g_auto(virBuffer) childBuf = VIR_BUFFER_INIT_CHILD(buf);
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+ g_auto(virBuffer) attrBuf = VIR_BUFFER_INITIALIZER;
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virBufferAsprintf(&childBuf, "<size unit='KiB'>%llu</size>\n", def->size);
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if (def->targetNode >= 0)
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@@ -25471,6 +25482,11 @@ virDomainMemoryTargetDefFormat(virBuffer *buf,
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if (def->target.virtio_mem.address)
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virBufferAsprintf(&childBuf, "<address base='0x%llx'/>\n",
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def->target.virtio_mem.address);
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+
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+ if (def->target.virtio_mem.dynamicMemslots) {
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+ virBufferAsprintf(&attrBuf, " dynamicMemslots='%s'",
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+ virTristateBoolTypeToString(def->target.virtio_mem.dynamicMemslots));
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+ }
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break;
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case VIR_DOMAIN_MEMORY_MODEL_SGX_EPC:
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@@ -25480,7 +25496,7 @@ virDomainMemoryTargetDefFormat(virBuffer *buf,
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break;
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}
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- virXMLFormatElement(buf, "target", NULL, &childBuf);
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+ virXMLFormatElement(buf, "target", &attrBuf, &childBuf);
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}
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static int
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diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
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index d176bda5f8..bd283d42df 100644
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--- a/src/conf/domain_conf.h
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+++ b/src/conf/domain_conf.h
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@@ -2676,6 +2676,7 @@ struct _virDomainMemoryDef {
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unsigned long long currentsize; /* kibibytes, valid for an active
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domain only and parsed */
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unsigned long long address; /* address where memory is mapped */
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+ virTristateBool dynamicMemslots;
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} virtio_mem;
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struct {
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} sgx_epc;
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diff --git a/src/conf/schemas/domaincommon.rng b/src/conf/schemas/domaincommon.rng
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index a34427c330..df44cd9857 100644
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--- a/src/conf/schemas/domaincommon.rng
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+++ b/src/conf/schemas/domaincommon.rng
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@@ -7268,6 +7268,11 @@
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<define name="memorydev-target">
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<element name="target">
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+ <optional>
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+ <attribute name="dynamicMemslots">
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+ <ref name="virYesNo"/>
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+ </attribute>
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+ </optional>
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<interleave>
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<element name="size">
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<ref name="scaledInteger"/>
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diff --git a/tests/qemuxml2argvdata/memory-hotplug-virtio-mem.xml b/tests/qemuxml2argvdata/memory-hotplug-virtio-mem.xml
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index 52fa6b14e9..20282a131b 100644
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--- a/tests/qemuxml2argvdata/memory-hotplug-virtio-mem.xml
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+++ b/tests/qemuxml2argvdata/memory-hotplug-virtio-mem.xml
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@@ -60,7 +60,7 @@
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<nodemask>1-3</nodemask>
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<pagesize unit='KiB'>2048</pagesize>
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</source>
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- <target>
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+ <target dynamicMemslots='yes'>
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<size unit='KiB'>2097152</size>
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<node>0</node>
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<block unit='KiB'>2048</block>
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--
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2.43.0
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