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Commit 366baf28 authored by Alexey Kardashevskiy's avatar Alexey Kardashevskiy Committed by Paul Mackerras
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KVM: PPC: Use RCU for arch.spapr_tce_tables 



At the moment only spapr_tce_tables updates are protected against races
but not lookups. This fixes missing protection by using RCU for the list.
As lookups also happen in real mode, this uses
list_for_each_entry_lockless() (which is expected not to access any
vmalloc'd memory).

This converts release_spapr_tce_table() to a RCU scheduled handler.

Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent fcbb2ce6

arch/powerpc/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -183,6 +183,7 @@ struct kvmppc_spapr_tce_table { 
	struct kvm *kvm;

	u64 liobn;

	u32 window_size;

	struct rcu_head rcu;

	struct page *pages[0];

};

arch/powerpc/kvm/book3s.c

+1 −1
Original line number Diff line number Diff line
@@ -807,7 +807,7 @@ int kvmppc_core_init_vm(struct kvm *kvm) 
{



#ifdef CONFIG_PPC64

	INIT_LIST_HEAD(&kvm->arch.spapr_tce_tables);

	INIT_LIST_HEAD_RCU(&kvm->arch.spapr_tce_tables);

	INIT_LIST_HEAD(&kvm->arch.rtas_tokens);

#endif

arch/powerpc/kvm/book3s_64_vio.c

+11 −9
Original line number Diff line number Diff line
@@ -45,19 +45,16 @@ static long kvmppc_stt_npages(unsigned long window_size) 
		     * sizeof(u64), PAGE_SIZE) / PAGE_SIZE;

}



static void release_spapr_tce_table(struct kvmppc_spapr_tce_table *stt)

static void release_spapr_tce_table(struct rcu_head *head)

{

	struct kvm *kvm = stt->kvm;

	struct kvmppc_spapr_tce_table *stt = container_of(head,

			struct kvmppc_spapr_tce_table, rcu);

	int i;



	mutex_lock(&kvm->lock);

	list_del(&stt->list);

	for (i = 0; i < kvmppc_stt_npages(stt->window_size); i++)

		__free_page(stt->pages[i]);

	kfree(stt);

	mutex_unlock(&kvm->lock);



	kvm_put_kvm(kvm);

	kfree(stt);

}



static int kvm_spapr_tce_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
@@ -88,7 +85,12 @@ static int kvm_spapr_tce_release(struct inode *inode, struct file *filp) 
{

	struct kvmppc_spapr_tce_table *stt = filp->private_data;



	release_spapr_tce_table(stt);

	list_del_rcu(&stt->list);



	kvm_put_kvm(stt->kvm);



	call_rcu(&stt->rcu, release_spapr_tce_table);



	return 0;

}
@@ -131,7 +133,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, 
	kvm_get_kvm(kvm);



	mutex_lock(&kvm->lock);

	list_add(&stt->list, &kvm->arch.spapr_tce_tables);

	list_add_rcu(&stt->list, &kvm->arch.spapr_tce_tables);



	mutex_unlock(&kvm->lock);

arch/powerpc/kvm/book3s_64_vio_hv.c

+1 −1
Original line number Diff line number Diff line
@@ -51,7 +51,7 @@ static struct kvmppc_spapr_tce_table *kvmppc_find_table(struct kvm_vcpu *vcpu, 
	struct kvm *kvm = vcpu->kvm;

	struct kvmppc_spapr_tce_table *stt;



	list_for_each_entry(stt, &kvm->arch.spapr_tce_tables, list)

	list_for_each_entry_lockless(stt, &kvm->arch.spapr_tce_tables, list)

		if (stt->liobn == liobn)

			return stt;