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KVM: PPC: Use RCU for arch.spapr_tce_tables

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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: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Alexey Kardashevskiy 2016-02-15 12:55:05 +11:00 committed by Paul Mackerras
parent fcbb2ce672
commit 366baf28ee
4 changed files with 14 additions and 11 deletions
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1
arch/powerpc/include/asm/kvm_host.h
View File

@ -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];
};

2
arch/powerpc/kvm/book3s.c
View File

@ -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

20
arch/powerpc/kvm/book3s_64_vio.c
View File

@ -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);

2
arch/powerpc/kvm/book3s_64_vio_hv.c
View File

@ -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;