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From: Paolo Bonzini <pbonzini@redhat.com>
To: speck@linutronix.de
Subject: [MODERATED] [PATCH v7 4/5] NX 4
Date: Thu, 24 Oct 2019 18:34:29 +0200	[thread overview]
Message-ID: <1571934870-34323-5-git-send-email-pbonzini@redhat.com> (raw)
In-Reply-To: <1571934870-34323-1-git-send-email-pbonzini@redhat.com>

From: Junaid Shahid <junaids@google.com>
Subject: [PATCH v7 4/5] kvm: Add helper function for creating VM worker

 threads

This adds a function to create a kernel thread associated with a given
VM. In particular, it ensures that the worker thread inherits the
priority and cgroups of the calling thread.

Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/linux/kvm_host.h |  6 ++++
 virt/kvm/kvm_main.c      | 84 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a817e446c9aa..d0f3939f0f6c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1382,4 +1382,10 @@ static inline int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
 }
 #endif /* CONFIG_HAVE_KVM_VCPU_RUN_PID_CHANGE */
 
+typedef int (*kvm_vm_thread_fn_t)(struct kvm *kvm, uintptr_t data);
+
+int kvm_vm_create_worker_thread(struct kvm *kvm, kvm_vm_thread_fn_t thread_fn,
+				uintptr_t data, const char *name,
+				struct task_struct **thread_ptr);
+
 #endif
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index b8534c6b8cf6..35c4d9aac184 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -50,6 +50,7 @@
 #include <linux/bsearch.h>
 #include <linux/io.h>
 #include <linux/lockdep.h>
+#include <linux/kthread.h>
 
 #include <asm/processor.h>
 #include <asm/ioctl.h>
@@ -4379,3 +4380,86 @@ void kvm_exit(void)
 	kvm_vfio_ops_exit();
 }
 EXPORT_SYMBOL_GPL(kvm_exit);
+
+struct kvm_vm_worker_thread_context {
+	struct kvm *kvm;
+	struct task_struct *parent;
+	struct completion init_done;
+	kvm_vm_thread_fn_t thread_fn;
+	uintptr_t data;
+	int err;
+};
+
+static int kvm_vm_worker_thread(void *context)
+{
+	/*
+	 * The init_context is allocated on the stack of the parent thread, so
+	 * we have to locally copy anything that is needed beyond initialization
+	 */
+	struct kvm_vm_worker_thread_context *init_context = context;
+	struct kvm *kvm = init_context->kvm;
+	kvm_vm_thread_fn_t thread_fn = init_context->thread_fn;
+	uintptr_t data = init_context->data;
+	int err;
+
+	err = kthread_park(current);
+	/* kthread_park(current) is never supposed to return an error */
+	WARN_ON(err != 0);
+	if (err)
+		goto init_complete;
+
+	err = cgroup_attach_task_all(init_context->parent, current);
+	if (err) {
+		kvm_err("%s: cgroup_attach_task_all failed with err %d\n",
+			__func__, err);
+		goto init_complete;
+	}
+
+	set_user_nice(current, task_nice(init_context->parent));
+
+init_complete:
+	init_context->err = err;
+	complete(&init_context->init_done);
+	init_context = NULL;
+
+	if (err)
+		return err;
+
+	/* Wait to be woken up by the spawner before proceeding. */
+	kthread_parkme();
+
+	if (!kthread_should_stop())
+		err = thread_fn(kvm, data);
+
+	return err;
+}
+
+int kvm_vm_create_worker_thread(struct kvm *kvm, kvm_vm_thread_fn_t thread_fn,
+				uintptr_t data, const char *name,
+				struct task_struct **thread_ptr)
+{
+	struct kvm_vm_worker_thread_context init_context = {};
+	struct task_struct *thread;
+
+	*thread_ptr = NULL;
+	init_context.kvm = kvm;
+	init_context.parent = current;
+	init_context.thread_fn = thread_fn;
+	init_context.data = data;
+	init_completion(&init_context.init_done);
+
+	thread = kthread_run(kvm_vm_worker_thread, &init_context,
+			     "%s-%d", name, task_pid_nr(current));
+	if (IS_ERR(thread))
+		return PTR_ERR(thread);
+
+	/* kthread_run is never supposed to return NULL */
+	WARN_ON(thread == NULL);
+
+	wait_for_completion(&init_context.init_done);
+
+	if (!init_context.err)
+		*thread_ptr = thread;
+
+	return init_context.err;
+}
-- 
1.8.3.1

  parent reply	other threads:[~2019-10-24 16:34 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-24 16:34 [MODERATED] [PATCH v7 0/5] NX 0 Paolo Bonzini
2019-10-24 16:34 ` [MODERATED] [PATCH v7 1/5] NX 1 Paolo Bonzini
2019-10-30 18:38   ` [MODERATED] " Josh Poimboeuf
2019-10-31 11:05     ` Paolo Bonzini
2019-10-24 16:34 ` [MODERATED] [PATCH v7 2/5] NX 2 Paolo Bonzini
2019-10-24 16:34 ` [MODERATED] [PATCH v7 3/5] NX 3 Paolo Bonzini
2019-10-25  8:37   ` [MODERATED] Re: ***UNCHECKED*** " Joerg Roedel
2019-10-25  8:48     ` Paolo Bonzini
2019-10-25  9:03       ` [MODERATED] Re: ***UNCHECKED*** " Joerg Roedel
2019-10-25  9:08         ` Paolo Bonzini
2019-10-25  9:45           ` [MODERATED] Re: ***UNCHECKED*** " Joerg Roedel
2019-10-25 10:39             ` Paolo Bonzini
2019-10-29 20:33               ` mark gross
2019-10-31 11:02                 ` Paolo Bonzini
2019-10-24 16:34 ` Paolo Bonzini [this message]
2019-10-24 16:34 ` [MODERATED] [PATCH v7 5/5] NX 5 Paolo Bonzini
2019-10-24 18:27 ` [MODERATED] Re: [PATCH v7 0/5] NX 0 Ben Hutchings
2019-10-24 18:56   ` Paolo Bonzini
  -- strict thread matches above, loose matches on Subject: below --
2019-10-24  7:34 [MODERATED] " Paolo Bonzini
2019-10-24  7:34 ` [MODERATED] [PATCH v7 4/5] NX 4 Paolo Bonzini

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