qemu: Extract logic to determine the mlock limit size for VFIO

New function qemuDomainGetMlockLimitBytes will now handle the
calculation so that it unifies the logic to one place and allows later
reuse.

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 882454156df36e9b6a069af49ac245839168510d..9acf8e42e1408322c944fd92b8c1096c3f37ad4a 100644 (file)
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -11447,22 +11447,8 @@ qemuBuildCommandLine(virConnectPtr conn,
             goto error;
     }
 
-    if (mlock) {
-        unsigned long long memKB;
-
-        /* VFIO requires all of the guest's memory to be
-         * locked resident, plus some amount for IO
-         * space. Alex Williamson suggested adding 1GiB for IO
-         * space just to be safe (some finer tuning might be
-         * nice, though).
-         */
-        if (virMemoryLimitIsSet(def->mem.hard_limit))
-            memKB = def->mem.hard_limit;
-        else
-            memKB = virDomainDefGetMemoryActual(def) + 1024 * 1024;
-
-        virCommandSetMaxMemLock(cmd, memKB * 1024);
-    }
+    if (mlock)
+        virCommandSetMaxMemLock(cmd, qemuDomainGetMlockLimitBytes(def));
 
     if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_MSG_TIMESTAMP) &&
         cfg->logTimestamp)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 890d8ed1117e5dc704b569ad4109d6e443abc41c..f016e8b3f6223256b21835458beb3063496a4eb3 100644 (file)
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -3616,3 +3616,30 @@ qemuDomainUpdateCurrentMemorySize(virQEMUDriverPtr driver,
 
     return 0;
 }
+
+
+/**
+ * qemuDomainGetMlockLimitBytes:
+ *
+ * @def: domain definition
+ *
+ * Returns the size of the memory in bytes that needs to be set as
+ * RLIMIT_MEMLOCK for purpose of VFIO device passthrough.
+ * If a mem.hard_limit is set, then that value is preferred; otherwise, the
+ * value returned may depend upon the architecture or devices present.
+ */
+unsigned long long
+qemuDomainGetMlockLimitBytes(virDomainDefPtr def)
+{
+    unsigned long long memKB;
+
+    /* VFIO requires all of the guest's memory to be locked resident, plus some
+     * amount for IO space. Alex Williamson suggested adding 1GiB for IO space
+     * just to be safe (some finer tuning might be nice, though). */
+    if (virMemoryLimitIsSet(def->mem.hard_limit))
+        memKB = def->mem.hard_limit;
+    else
+        memKB = virDomainDefGetMemoryActual(def) + 1024 * 1024;
+
+    return memKB << 10;
+}

diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 64cd7e1a124ec6f47df1e5c7b3a48560c93b3759..e34370b08b56eaebed915103ee22115f896e8af1 100644 (file)
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -482,4 +482,6 @@ bool qemuDomainMachineIsS390CCW(const virDomainDef *def);
 int qemuDomainUpdateCurrentMemorySize(virQEMUDriverPtr driver,
                                       virDomainObjPtr vm);
 
+unsigned long long qemuDomainGetMlockLimitBytes(virDomainDefPtr def);
+
 #endif /* __QEMU_DOMAIN_H__ */

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 8f2fda996e3faea9b729a78b403773d1b54da122..e7fc036471c21abe639fdf646f8c3b77a12c9dc9 100644 (file)
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -1254,7 +1254,6 @@ qemuDomainAttachHostPCIDevice(virQEMUDriverPtr driver,
     bool teardowncgroup = false;
     bool teardownlabel = false;
     int backend;
-    unsigned long long memKB;
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
     unsigned int flags = 0;
 
@@ -1279,20 +1278,8 @@ qemuDomainAttachHostPCIDevice(virQEMUDriverPtr driver,
             goto error;
         }
 
-        /* VFIO requires all of the guest's memory to be locked
-         * resident (plus an additional 1GiB to cover IO space). During
-         * hotplug, the guest's memory may already be locked, but it
-         * doesn't hurt to "change" the limit to the same value.
-         * NB: the domain's memory tuning parameters are stored as
-         * Kibibytes, but virProcessSetMaxMemLock expects the value in
-         * bytes.
-         */
-        if (virMemoryLimitIsSet(vm->def->mem.hard_limit))
-            memKB = vm->def->mem.hard_limit;
-        else
-            memKB = virDomainDefGetMemoryActual(vm->def) + (1024 * 1024);
-
-        virProcessSetMaxMemLock(vm->pid, memKB * 1024);
+        /* setup memory locking limits, that are necessary for VFIO */
+        virProcessSetMaxMemLock(vm->pid, qemuDomainGetMlockLimitBytes(vm->def));
         break;
 
     default: