From ed413584e982b24442ab860874e307f50d7fdb10 Mon Sep 17 00:00:00 2001

Message-Id: <ed413584e982b24442ab860874e307f50d7fdb10@dist-git>

From: Peter Krempa <pkrempa@redhat.com>

Date: Thu, 12 Nov 2015 08:40:42 +0100

Subject: [PATCH] qemu: Extract logic to determine the mlock limit size for

 VFIO

https://bugzilla.redhat.com/show_bug.cgi?id=1280420

New function qemuDomainGetMlockLimitBytes will now handle the

calculation so that it unifies the logic to one place and allows later

reuse.

(cherry picked from commit fbc58cfcaeffdd4a350cf6abd67da6006f01b148)

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>

---

 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 9c80e0c..7f8a31b 100644

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

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

@@ -11146,22 +11146,8 @@ 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 1528cfd..944817d 100644

--- a/src/qemu/qemu_domain.c

+++ b/src/qemu/qemu_domain.c

@@ -3422,3 +3422,30 @@ 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 e283b58..54e7cd9 100644

--- a/src/qemu/qemu_domain.h

+++ b/src/qemu/qemu_domain.h

@@ -475,4 +475,6 @@ 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 bd96abf..d96f572 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:

-- 

2.6.3