From 0e4524a5d341e719e8ee9ee7db5d58e2c5a4c10e Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Thu, 6 Jul 2017 14:44:28 +0200 Subject: [PATCH] KVM: mark vcpu->pid pointer as rcu protected We do use rcu to protect the pid pointer. Mark it as such and adopt all code to use the proper access methods. This was detected by sparse. "virt/kvm/kvm_main.c:2248:15: error: incompatible types in comparison expression (different address spaces)" Signed-off-by: Christian Borntraeger Reviewed-by: Paolo Bonzini --- include/linux/kvm_host.h | 2 +- virt/kvm/kvm_main.c | 15 +++++++++++---- 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 0b50e7b35ed4..bcd37b855c66 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -234,7 +234,7 @@ struct kvm_vcpu { int guest_fpu_loaded, guest_xcr0_loaded; struct swait_queue_head wq; - struct pid *pid; + struct pid __rcu *pid; int sigset_active; sigset_t sigset; struct kvm_vcpu_stat stat; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 19f0ecb9b93e..fc2d58312fd5 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -293,7 +293,12 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_init); void kvm_vcpu_uninit(struct kvm_vcpu *vcpu) { - put_pid(vcpu->pid); + /* + * no need for rcu_read_lock as VCPU_RUN is the only place that + * will change the vcpu->pid pointer and on uninit all file + * descriptors are already gone. + */ + put_pid(rcu_dereference_protected(vcpu->pid, 1)); kvm_arch_vcpu_uninit(vcpu); free_page((unsigned long)vcpu->run); } @@ -2551,13 +2556,14 @@ static long kvm_vcpu_ioctl(struct file *filp, if (r) return r; switch (ioctl) { - case KVM_RUN: + case KVM_RUN: { + struct pid *oldpid; r = -EINVAL; if (arg) goto out; - if (unlikely(vcpu->pid != current->pids[PIDTYPE_PID].pid)) { + oldpid = rcu_access_pointer(vcpu->pid); + if (unlikely(oldpid != 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); @@ -2568,6 +2574,7 @@ static long kvm_vcpu_ioctl(struct file *filp, r = kvm_arch_vcpu_ioctl_run(vcpu, vcpu->run); trace_kvm_userspace_exit(vcpu->run->exit_reason, r); break; + } case KVM_GET_REGS: { struct kvm_regs *kvm_regs;