From: Michal Privoznik <mprivozn@redhat.com>
Date: Tue, 16 Mar 2021 18:09:27 +0000 (+0100)
Subject: qemuDomainSetMemoryFlags: Take virtio-mem into consideration
X-Git-Tag: v7.9.0-rc1~289
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b1c3b5dfecaa37742e30bde00d9d230131e39f83;p=thirdparty%2Flibvirt.git

qemuDomainSetMemoryFlags: Take virtio-mem into consideration

The qemuDomainSetMemoryFlags() allows for memballoon
(<currentMemory/>) changes for both active and inactive guests.
And just before doing any change, we have to make sure that the
new size is not greater than the total memory (<memory/>).

However, the total memory includes not only the regular guest
memory, but also sum of maximum sizes of all virtio-mems (in fact
all memory devices for that matter). But virtio-mem devices are
modified differently (via virDomainUpdateDevice()) and thus the
upper limit for new balloon size has to be lowered.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 9f3154e548..760d30a867 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -2381,12 +2381,28 @@ static int qemuDomainSetMemoryFlags(virDomainPtr dom, unsigned long newmem,
     } else {
         /* resize the current memory */
         unsigned long oldmax = 0;
+        size_t i;
 
-        if (def)
+        if (def) {
             oldmax = virDomainDefGetMemoryTotal(def);
+
+            /* While virtio-mem is regular mem from guest POV, it can't be
+             * modified through this API. */
+            for (i = 0; i < def->nmems; i++) {
+                if (def->mems[i]->model == VIR_DOMAIN_MEMORY_MODEL_VIRTIO_MEM)
+                    oldmax -= def->mems[i]->size;
+            }
+        }
+
         if (persistentDef) {
-            if (!oldmax || oldmax > virDomainDefGetMemoryTotal(persistentDef))
+            if (!def || oldmax > virDomainDefGetMemoryTotal(persistentDef)) {
                 oldmax = virDomainDefGetMemoryTotal(persistentDef);
+
+                for (i = 0; i < persistentDef->nmems; i++) {
+                    if (persistentDef->mems[i]->model == VIR_DOMAIN_MEMORY_MODEL_VIRTIO_MEM)
+                        oldmax -= persistentDef->mems[i]->size;
+                }
+            }
         }
 
         if (newmem > oldmax) {