Re: [PATCH v2 44/45] KVM: Move putting of vcpu->pid to kvm_vcpu_destroy()

2019-12-20 Thread Cornelia Huck
On Wed, 18 Dec 2019 13:55:29 -0800
Sean Christopherson  wrote:

> Move the putting of vcpu->pid to kvm_vcpu_destroy().  vcpu->pid is
> guaranteed to be NULL when kvm_vcpu_uninit() is called in the error path
> of kvm_vm_ioctl_create_vcpu(), e.g. it is explicitly nullified by
> kvm_vcpu_init() and is only changed by KVM_RUN.
> 
> No functional change intended.
> 
> Acked-by: Christoffer Dall 
> Signed-off-by: Sean Christopherson 
> ---
>  virt/kvm/kvm_main.c | 13 +++--
>  1 file changed, 7 insertions(+), 6 deletions(-)

Reviewed-by: Cornelia Huck 

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[PATCH v2 44/45] KVM: Move putting of vcpu->pid to kvm_vcpu_destroy()

2019-12-18 Thread Sean Christopherson
Move the putting of vcpu->pid to kvm_vcpu_destroy().  vcpu->pid is
guaranteed to be NULL when kvm_vcpu_uninit() is called in the error path
of kvm_vm_ioctl_create_vcpu(), e.g. it is explicitly nullified by
kvm_vcpu_init() and is only changed by KVM_RUN.

No functional change intended.

Acked-by: Christoffer Dall 
Signed-off-by: Sean Christopherson 
---
 virt/kvm/kvm_main.c | 13 +++--
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 21533a472ead..6912d81ca32d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -352,12 +352,6 @@ static int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm 
*kvm, unsigned id)
 
 static void kvm_vcpu_uninit(struct kvm_vcpu *vcpu)
 {
-   /*
-* 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));
free_page((unsigned long)vcpu->run);
 }
 
@@ -365,6 +359,13 @@ void kvm_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
kvm_arch_vcpu_destroy(vcpu);
 
+   /*
+* No need for rcu_read_lock as VCPU_RUN is the only place that changes
+* the vcpu->pid pointer, and at destruction time all file descriptors
+* are already gone.
+*/
+   put_pid(rcu_dereference_protected(vcpu->pid, 1));
+
kvm_vcpu_uninit(vcpu);
kmem_cache_free(kvm_vcpu_cache, vcpu);
 }
-- 
2.24.1

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