From fbc58cfcaeffdd4a350cf6abd67da6006f01b148 Mon Sep 17 00:00:00 2001
From: Peter Krempa <pkrempa@redhat.com>
Date: Fri, 6 Nov 2015 15:51:33 +0100
Subject: [PATCH] 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.
---
 src/qemu/qemu_command.c | 18 ++----------------
 src/qemu/qemu_domain.c  | 27 +++++++++++++++++++++++++++
 src/qemu/qemu_domain.h  |  2 ++
 src/qemu/qemu_hotplug.c | 17 ++---------------
 4 files changed, 33 insertions(+), 31 deletions(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 882454156d..9acf8e42e1 100644
--- 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 890d8ed111..f016e8b3f6 100644
--- 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 64cd7e1a12..e34370b08b 100644
--- 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 8f2fda996e..e7fc036471 100644
--- 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: