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KVM: mark vcpu->pid pointer as rcu protected

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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 <borntraeger@de.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Christian Borntraeger 2017-07-06 14:44:28 +02:00
parent 1372324b32
commit 0e4524a5d3
2 changed files with 12 additions and 5 deletions
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2
include/linux/kvm_host.h
View File

@ -234,7 +234,7 @@ struct kvm_vcpu {
int guest_fpu_loaded, guest_xcr0_loaded; int guest_fpu_loaded, guest_xcr0_loaded;
struct swait_queue_head wq; struct swait_queue_head wq;
struct pid *pid; struct pid __rcu *pid;
int sigset_active; int sigset_active;
sigset_t sigset; sigset_t sigset;
struct kvm_vcpu_stat stat; struct kvm_vcpu_stat stat;

15
virt/kvm/kvm_main.c
View File

@ -293,7 +293,12 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_init);
void kvm_vcpu_uninit(struct kvm_vcpu *vcpu) 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); kvm_arch_vcpu_uninit(vcpu);
free_page((unsigned long)vcpu->run); free_page((unsigned long)vcpu->run);
} }
@ -2551,13 +2556,14 @@ static long kvm_vcpu_ioctl(struct file *filp,
if (r) if (r)
return r; return r;
switch (ioctl) { switch (ioctl) {
case KVM_RUN: case KVM_RUN: {
struct pid *oldpid;
r = -EINVAL; r = -EINVAL;
if (arg) if (arg)
goto out; 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. */ /* The thread running this VCPU changed. */
struct pid *oldpid = vcpu->pid;
struct pid *newpid = get_task_pid(current, PIDTYPE_PID); struct pid *newpid = get_task_pid(current, PIDTYPE_PID);
rcu_assign_pointer(vcpu->pid, newpid); 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); r = kvm_arch_vcpu_ioctl_run(vcpu, vcpu->run);
trace_kvm_userspace_exit(vcpu->run->exit_reason, r); trace_kvm_userspace_exit(vcpu->run->exit_reason, r);
break; break;
}
case KVM_GET_REGS: { case KVM_GET_REGS: {
struct kvm_regs *kvm_regs; struct kvm_regs *kvm_regs;