linux-kernel - [PATCH -v8a 6/7] kvm: keep track of which task is running a KVM vcpu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20110201095241.2bdccb8e@annuminas.surriel.com>
Date:	Tue, 1 Feb 2011 09:52:41 -0500
From:	Rik van Riel <riel@...hat.com>
To:	kvm@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Avi Kiviti <avi@...hat.com>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Mike Galbraith <efault@....de>,
	Chris Wright <chrisw@...s-sol.org>,
	"Nakajima, Jun" <jun.nakajima@...el.com>
Subject: [PATCH -v8a 6/7] kvm: keep track of which task is running a KVM
 vcpu

Keep track of which task is running a KVM vcpu.  This helps us
figure out later what task to wake up if we want to boost a
vcpu that got preempted.

Unfortunately there are no guarantees that the same task
always keeps the same vcpu, so we can only track the task
across a single "run" of the vcpu.

Signed-off-by: Rik van Riel <riel@...hat.com>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a055742..9d56ed5 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -81,6 +81,7 @@ struct kvm_vcpu {
 #endif
 	int vcpu_id;
 	struct mutex mutex;
+	struct pid *pid;
 	int   cpu;
 	atomic_t guest_mode;
 	struct kvm_run *run;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5225052..0fa9a48 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -117,6 +117,14 @@ void vcpu_load(struct kvm_vcpu *vcpu)
 	int cpu;
 
 	mutex_lock(&vcpu->mutex);
+	if (unlikely(vcpu->pid != current->pids[PIDTYPE_PID].pid)) {
+		/* The thread running this VCPU changed. */
+		struct pid *oldpid = vcpu->pid;
+		struct pid *newpid = get_task_pid(current, PIDTYPE_PID);
+		rcu_assign_pointer(vcpu->pid, newpid);
+		synchronize_rcu();
+		put_pid(oldpid);
+	}
 	cpu = get_cpu();
 	preempt_notifier_register(&vcpu->preempt_notifier);
 	kvm_arch_vcpu_load(vcpu, cpu);
@@ -185,6 +193,7 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
 	vcpu->cpu = -1;
 	vcpu->kvm = kvm;
 	vcpu->vcpu_id = id;
+	vcpu->pid = NULL;
 	init_waitqueue_head(&vcpu->wq);
 
 	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
@@ -208,6 +217,7 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_init);
 
 void kvm_vcpu_uninit(struct kvm_vcpu *vcpu)
 {
+	put_pid(vcpu->pid);
 	kvm_arch_vcpu_uninit(vcpu);
 	free_page((unsigned long)vcpu->run);
 }
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/