From 45a585374500f4e4f1684c9dafe89269344c79b1 Mon Sep 17 00:00:00 2001

Message-Id: <45a585374500f4e4f1684c9dafe89269344c79b1@dist-git>

From: Michal Privoznik <mprivozn@redhat.com>

Date: Tue, 7 Mar 2023 14:05:54 +0100

Subject: [PATCH] qemuBuildThreadContextProps: Prune .node-affinity wrt

 <emulatorpin/>

When a thread-context object is specified on the cmd line, then

QEMU spawns a thread and sets its affinity to the list of NUMA

nodes specified in .node-affinity attribute. And this works just

fine, until the main QEMU thread itself is not restricted.

Because of v5.3.0-rc1~18 we restrict the main emulator thread

even before QEMU is executed and thus then it tries to set

affinity of a thread-context thread, it inevitably fails with:

  Setting CPU affinity failed: Invalid argument

Now, we could lift the pinning temporarily, let QEMU spawn all

thread-context threads, and enforce pinning again, but that would

require some form of communication with QEMU (maybe -preconfig?).

But that would still be wrong, because it would circumvent

<emulatorpin/>.

Technically speaking, thread-context is an internal

implementation detail of QEMU, and if it weren't for it, the main

emulator thread would be doing the allocation. Therefore, we

should honor the pinning and prune the list of node so that

inaccessible ones are dropped.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2154750

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

Reviewed-by: Kristina Hanicova <khanicov@redhat.com>

Reviewed-by: Andrea Bolognani <abologna@redhat.com>

(cherry picked from commit df2ef2e706ec5960761bdbf619ea33be99482a15)

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2185039

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

---

 src/qemu/qemu_command.c                       | 25 ++++++++++++++++---

 src/qemu/qemu_command.h                       |  1 +

 ...emory-hotplug-dimm-addr.x86_64-latest.args |  2 +-

 3 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c

index 346967f51c..b36005d248 100644

--- a/src/qemu/qemu_command.c

+++ b/src/qemu/qemu_command.c

@@ -3533,7 +3533,7 @@ qemuBuildMemoryDimmBackendStr(virCommand *cmd,

                                     def, mem, true, false, &nodemask) < 0)

         return -1;

-    if (qemuBuildThreadContextProps(&tcProps, &props, priv, nodemask) < 0)

+    if (qemuBuildThreadContextProps(&tcProps, &props, def, priv, nodemask) < 0)

         return -1;

     if (tcProps &&

@@ -3630,10 +3630,13 @@ qemuBuildMemoryDeviceProps(virQEMUDriverConfig *cfg,

 int

 qemuBuildThreadContextProps(virJSONValue **tcProps,

                             virJSONValue **memProps,

+                            const virDomainDef *def,

                             qemuDomainObjPrivate *priv,

                             virBitmap *nodemask)

 {

     g_autoptr(virJSONValue) props = NULL;

+    virBitmap *emulatorpin = NULL;

+    g_autoptr(virBitmap) emulatorNodes = NULL;

     g_autofree char *tcAlias = NULL;

     const char *memalias = NULL;

     bool prealloc = false;

@@ -3650,6 +3653,22 @@ qemuBuildThreadContextProps(virJSONValue **tcProps,

         !prealloc)

         return 0;

+    emulatorpin = qemuDomainEvaluateCPUMask(def,

+                                            def->cputune.emulatorpin,

+                                            priv->autoNodeset);

+

+    if (emulatorpin && virNumaIsAvailable()) {

+        if (virNumaCPUSetToNodeset(emulatorpin, &emulatorNodes) < 0)

+            return -1;

+

+        virBitmapIntersect(emulatorNodes, nodemask);

+

+        if (virBitmapIsAllClear(emulatorNodes))

+            return 0;

+

+        nodemask = emulatorNodes;

+    }

+

     memalias = virJSONValueObjectGetString(*memProps, "id");

     if (!memalias) {

         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",

@@ -7064,7 +7083,7 @@ qemuBuildMemCommandLineMemoryDefaultBackend(virCommand *cmd,

                                     def, &mem, false, true, &nodemask) < 0)

         return -1;

-    if (qemuBuildThreadContextProps(&tcProps, &props, priv, nodemask) < 0)

+    if (qemuBuildThreadContextProps(&tcProps, &props, def, priv, nodemask) < 0)

         return -1;

     if (tcProps &&

@@ -7393,7 +7412,7 @@ qemuBuildNumaCommandLine(virQEMUDriverConfig *cfg,

             g_autoptr(virJSONValue) tcProps = NULL;

             if (qemuBuildThreadContextProps(&tcProps, &nodeBackends[i],

-                                            priv, nodemask[i]) < 0)

+                                            def, priv, nodemask[i]) < 0)

                 goto cleanup;

             if (tcProps &&

diff --git a/src/qemu/qemu_command.h b/src/qemu/qemu_command.h

index 17f326d13b..5fdb138030 100644

--- a/src/qemu/qemu_command.h

+++ b/src/qemu/qemu_command.h

@@ -153,6 +153,7 @@ qemuBuildMemoryDeviceProps(virQEMUDriverConfig *cfg,

 int

 qemuBuildThreadContextProps(virJSONValue **tcProps,

                             virJSONValue **memProps,

+                            const virDomainDef *def,

                             qemuDomainObjPrivate *priv,

                             virBitmap *nodemask);

diff --git a/tests/qemuxml2argvdata/memory-hotplug-dimm-addr.x86_64-latest.args b/tests/qemuxml2argvdata/memory-hotplug-dimm-addr.x86_64-latest.args

index 4e9bbde448..bbfb0f9a9e 100644

--- a/tests/qemuxml2argvdata/memory-hotplug-dimm-addr.x86_64-latest.args

+++ b/tests/qemuxml2argvdata/memory-hotplug-dimm-addr.x86_64-latest.args

@@ -29,7 +29,7 @@ XDG_CONFIG_HOME=/tmp/lib/domain--1-QEMUGuest1/.config \

 -no-acpi \

 -boot strict=on \

 -device '{"driver":"piix3-usb-uhci","id":"usb","bus":"pci.0","addr":"0x1.0x2"}' \

--object '{"qom-type":"thread-context","id":"tc-memdimm0","node-affinity":[1,2,3]}' \

+-object '{"qom-type":"thread-context","id":"tc-memdimm0","node-affinity":[1,2]}' \

 -object '{"qom-type":"memory-backend-file","id":"memdimm0","mem-path":"/dev/hugepages2M/libvirt/qemu/-1-QEMUGuest1","prealloc":true,"size":536870912,"host-nodes":[1,2,3],"policy":"bind","prealloc-context":"tc-memdimm0"}' \

 -device '{"driver":"pc-dimm","node":0,"memdev":"memdimm0","id":"dimm0","slot":0,"addr":4294967296}' \

 -object '{"qom-type":"memory-backend-ram","id":"memdimm2","size":536870912}' \

-- 

2.40.0