[PATCH 4/4] Check the kvm host cpu max limits in virConnectGetDomainCapabilities()

[Shivaprasad G Bhat <sbhat@xxxxxxxxxxxxxxxxxx>]

The qemu limit and host limit both should be considered for
the domain vcpu max limits.

Signed-off-by: Shivaprasad G Bhat <sbhat@xxxxxxxxxxxxxxxxxx>
---
 docs/formatdomaincaps.html.in  |    4 ++--
 src/conf/domain_capabilities.c |   10 +++++++---
 src/conf/domain_capabilities.h |    1 +
 src/qemu/qemu_capabilities.c   |   13 ++++++++++---
 src/qemu/qemu_capabilities.h   |    3 ++-
 src/qemu/qemu_driver.c         |    2 +-
 tests/domaincapstest.c         |    3 ++-
 7 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/docs/formatdomaincaps.html.in b/docs/formatdomaincaps.html.in
index d5a8414..d28a5b6 100644
--- a/docs/formatdomaincaps.html.in
+++ b/docs/formatdomaincaps.html.in
@@ -86,14 +86,14 @@
 <pre>
 &lt;domainCapabilities&gt;
   ...
-  &lt;vcpu max='255'/&gt;
+  &lt;vcpu max='255' suggested='96'/&gt;
   ...
 &lt;/domainCapabilities&gt;
 </pre>
 
     <dl>
       <dt><code>vcpu</code></dt>
-      <dd>The maximum number of supported virtual CPUs</dd>
+      <dd>The maximum number of supported virtual CPUs. The suggested attribute if present, gives the recommended maximum vcpus for the KVM host.</dd>
     </dl>
 
     <h3><a name="elementsOSBIOS">BIOS bootloader</a></h3>
diff --git a/src/conf/domain_capabilities.c b/src/conf/domain_capabilities.c
index 1676f0e..452cad4 100644
--- a/src/conf/domain_capabilities.c
+++ b/src/conf/domain_capabilities.c
@@ -329,9 +329,13 @@ virDomainCapsFormatInternal(virBufferPtr buf,
     virBufferAsprintf(buf, "<machine>%s</machine>\n", caps->machine);
     virBufferAsprintf(buf, "<arch>%s</arch>\n", arch_str);
 
-    if (caps->maxvcpus)
-        virBufferAsprintf(buf, "<vcpu max='%d'/>\n", caps->maxvcpus);
-
+    if (caps->maxvcpus) {
+        if (!caps->suggestedvcpus)
+            virBufferAsprintf(buf, "<vcpu max='%d'/>\n", caps->maxvcpus);
+        else
+            virBufferAsprintf(buf, "<vcpu max='%d' suggested='%d'/>\n",
+                          caps->maxvcpus, caps->suggestedvcpus);
+    }
     virDomainCapsOSFormat(buf, &caps->os);
 
     virBufferAddLit(buf, "<devices>\n");
diff --git a/src/conf/domain_capabilities.h b/src/conf/domain_capabilities.h
index 492a9cf..f440436 100644
--- a/src/conf/domain_capabilities.h
+++ b/src/conf/domain_capabilities.h
@@ -112,6 +112,7 @@ struct _virDomainCaps {
 
     /* Some machine specific info */
     int maxvcpus;
+    int suggestedvcpus;
 
     virDomainCapsOS os;
     virDomainCapsDeviceDisk disk;
diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 1ef5937..df10aa8 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -38,6 +38,7 @@
 #include "virbitmap.h"
 #include "virnodesuspend.h"
 #include "virnuma.h"
+#include "virhostcpu.h"
 #include "qemu_monitor.h"
 #include "virstring.h"
 #include "qemu_hostdev.h"
@@ -4333,16 +4334,22 @@ int
 virQEMUCapsFillDomainCaps(virDomainCapsPtr domCaps,
                           virQEMUCapsPtr qemuCaps,
                           virFirmwarePtr *firmwares,
-                          size_t nfirmwares)
+                          size_t nfirmwares,
+                          virDomainVirtType virttype)
 {
     virDomainCapsOSPtr os = &domCaps->os;
     virDomainCapsDeviceDiskPtr disk = &domCaps->disk;
     virDomainCapsDeviceHostdevPtr hostdev = &domCaps->hostdev;
     virDomainCapsDeviceGraphicsPtr graphics = &domCaps->graphics;
     virDomainCapsDeviceVideoPtr video = &domCaps->video;
-    int maxvcpus = virQEMUCapsGetMachineMaxCpus(qemuCaps, domCaps->machine);
+    int hostmaxvcpus = 0;
 
-    domCaps->maxvcpus = maxvcpus;
+    domCaps->maxvcpus = virQEMUCapsGetMachineMaxCpus(qemuCaps, domCaps->machine);
+    if (virttype == VIR_DOMAIN_VIRT_KVM) {
+        hostmaxvcpus = virHostCPUGetKVMVCPUs(VIR_HOSTCPU_KVM_MAXVCPUS);
+        domCaps->suggestedvcpus = virHostCPUGetKVMVCPUs(VIR_HOSTCPU_KVM_NR_VCPUS);
+        domCaps->maxvcpus = MIN(domCaps->maxvcpus, hostmaxvcpus);
+    }
 
     if (virQEMUCapsFillDomainOSCaps(os, firmwares, nfirmwares) < 0 ||
         virQEMUCapsFillDomainDeviceDiskCaps(qemuCaps,
diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
index f7ede4a..ffe07e5 100644
--- a/src/qemu/qemu_capabilities.h
+++ b/src/qemu/qemu_capabilities.h
@@ -494,6 +494,7 @@ int virQEMUCapsInitGuestFromBinary(virCapsPtr caps,
 int virQEMUCapsFillDomainCaps(virDomainCapsPtr domCaps,
                               virQEMUCapsPtr qemuCaps,
                               virFirmwarePtr *firmwares,
-                              size_t nfirmwares);
+                              size_t nfirmwares,
+                              virDomainVirtType virttype);
 
 #endif /* __QEMU_CAPABILITIES_H__*/
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 6b316a0..21aa053 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -18485,7 +18485,7 @@ qemuConnectGetDomainCapabilities(virConnectPtr conn,
         goto cleanup;
 
     if (virQEMUCapsFillDomainCaps(domCaps, qemuCaps,
-                                  cfg->firmwares, cfg->nfirmwares) < 0)
+                                  cfg->firmwares, cfg->nfirmwares, virttype) < 0)
         goto cleanup;
 
     ret = virDomainCapsFormat(domCaps);
diff --git a/tests/domaincapstest.c b/tests/domaincapstest.c
index 9fb2c97..ea438e3 100644
--- a/tests/domaincapstest.c
+++ b/tests/domaincapstest.c
@@ -129,7 +129,8 @@ fillQemuCaps(virDomainCapsPtr domCaps,
 
     if (virQEMUCapsFillDomainCaps(domCaps, qemuCaps,
                                   cfg->firmwares,
-                                  cfg->nfirmwares) < 0)
+                                  cfg->nfirmwares,
+                                  VIR_DOMAIN_VIRT_QEMU) < 0)
         goto cleanup;
 
     /* The function above tries to query host's KVM & VFIO capabilities by

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