libvirt/libvirt-qemu-Add-qemuDomainSetMaxMemLock-helper.patch

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From 2595c7716b19214b2729b41b86656f96a2cd18bc Mon Sep 17 00:00:00 2001
Message-Id: <2595c7716b19214b2729b41b86656f96a2cd18bc@dist-git>
From: Jiri Denemark <jdenemar@redhat.com>
Date: Wed, 22 Jun 2022 15:21:30 +0200
Subject: [PATCH] qemu: Add qemuDomainSetMaxMemLock helper
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
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=2089433
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