From 7f5b89a15bfcd964c7f2b6ccbf3c03fd867f93b5 Mon Sep 17 00:00:00 2001

Message-Id: <7f5b89a15bfcd964c7f2b6ccbf3c03fd867f93b5@dist-git>

From: Jiri Denemark <jdenemar@redhat.com>

Date: Wed, 22 Jun 2022 15:21:30 +0200

Subject: [PATCH] qemu: Add qemuDomainSetMaxMemLock helper

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qemuDomainAdjustMaxMemLock combined computing the desired limit with

applying it. This patch separates the code to apply a memory locking

limit to a new qemuDomainSetMaxMemLock helper for better reusability.

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

Reviewed-by: Ján Tomko <jtomko@redhat.com>

(cherry picked from commit dff51c7f5760ded8235076f55d082fe4363f2f78)

https://bugzilla.redhat.com/show_bug.cgi?id=2117272

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

---

 src/qemu/qemu_domain.c | 95 ++++++++++++++++++++++++++----------------

 src/qemu/qemu_domain.h |  3 ++

 2 files changed, 61 insertions(+), 37 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c

index ee7d310903..a81789f194 100644

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

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

@@ -9261,6 +9261,61 @@ qemuDomainGetMemLockLimitBytes(virDomainDef *def,

 }

+/**

+ * qemuDomainSetMaxMemLock:

+ * @vm: domain

+ * @limit: the desired memory locking limit

+ * @origPtr: where to store (or load from) the original value of the limit

+ *

+ * Set the memory locking limit for @vm unless it's already big enough. If

+ * @origPtr is non-NULL, the original value of the limit will be store there

+ * and can be restored by calling this function with @limit == 0.

+ *

+ * Returns: 0 on success, -1 otherwise.

+ */

+int

+qemuDomainSetMaxMemLock(virDomainObj *vm,

+                        unsigned long long limit,

+                        unsigned long long *origPtr)

+{

+    unsigned long long current = 0;

+

+    if (virProcessGetMaxMemLock(vm->pid, &current) < 0)

+        return -1;

+

+    if (limit > 0) {

+        VIR_DEBUG("Requested memory lock limit: %llu", limit);

+        /* If the limit is already high enough, we can assume

+         * that some external process is taking care of managing

+         * process limits and we shouldn't do anything ourselves:

+         * we're probably running in a containerized environment

+         * where we don't have enough privilege anyway */

+        if (current >= limit) {

+            VIR_DEBUG("Current limit %llu is big enough", current);

+            return 0;

+        }

+

+        /* If this is the first time adjusting the limit, save the current

+         * value so that we can restore it once memory locking is no longer

+         * required */

+        if (origPtr && *origPtr == 0)

+            *origPtr = current;

+    } else {

+        /* Once memory locking is no longer required, we can restore the

+         * original, usually very low, limit. But only if we actually stored

+         * the original limit before. */

+        if (!origPtr || *origPtr == 0)

+            return 0;

+

+        limit = *origPtr;

+        *origPtr = 0;

+        VIR_DEBUG("Resetting memory lock limit back to %llu", limit);

+    }

+

+    return virProcessSetMaxMemLock(vm->pid, limit);

+}

+

+

 /**

  * qemuDomainAdjustMaxMemLock:

  * @vm: domain

@@ -9282,43 +9337,9 @@ int

 qemuDomainAdjustMaxMemLock(virDomainObj *vm,

                            bool forceVFIO)

 {

-    qemuDomainObjPrivate *priv = vm->privateData;

-    unsigned long long currentMemLock = 0;

-    unsigned long long desiredMemLock = 0;

-

-    desiredMemLock = qemuDomainGetMemLockLimitBytes(vm->def, forceVFIO);

-    if (virProcessGetMaxMemLock(vm->pid, &currentMemLock) < 0)

-        return -1;

-

-    if (desiredMemLock > 0) {

-        if (currentMemLock < desiredMemLock) {

-            /* If this is the first time adjusting the limit, save the current

-             * value so that we can restore it once memory locking is no longer

-             * required */

-            if (priv->originalMemlock == 0) {

-                priv->originalMemlock = currentMemLock;

-            }

-        } else {

-            /* If the limit is already high enough, we can assume

-             * that some external process is taking care of managing

-             * process limits and we shouldn't do anything ourselves:

-             * we're probably running in a containerized environment

-             * where we don't have enough privilege anyway */

-            desiredMemLock = 0;

-        }

-    } else {

-        /* Once memory locking is no longer required, we can restore the

-         * original, usually very low, limit */

-        desiredMemLock = priv->originalMemlock;

-        priv->originalMemlock = 0;

-    }

-

-    if (desiredMemLock > 0 &&

-        virProcessSetMaxMemLock(vm->pid, desiredMemLock) < 0) {

-        return -1;

-    }

-

-    return 0;

+    return qemuDomainSetMaxMemLock(vm,

+                                   qemuDomainGetMemLockLimitBytes(vm->def, forceVFIO),

+                                   &QEMU_DOMAIN_PRIVATE(vm)->originalMemlock);

 }

diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h

index e9497d20de..6d1d23439a 100644

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

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

@@ -789,6 +789,9 @@ int qemuDomainAdjustMaxMemLock(virDomainObj *vm,

                                bool forceVFIO);

 int qemuDomainAdjustMaxMemLockHostdev(virDomainObj *vm,

                                       virDomainHostdevDef *hostdev);

+int qemuDomainSetMaxMemLock(virDomainObj *vm,

+                            unsigned long long limit,

+                            unsigned long long *origPtr);

 int qemuDomainDefValidateMemoryHotplug(const virDomainDef *def,

                                        const virDomainMemoryDef *mem);

-- 

2.35.1