diff options
author | Paul Mackerras <paulus@ozlabs.org> | 2019-05-29 11:54:00 +1000 |
---|---|---|
committer | Paul Mackerras <paulus@ozlabs.org> | 2019-05-29 13:44:36 +1000 |
commit | 1659e27d2bc1ef47b6d031abe01b467f18cb72d9 (patch) | |
tree | 9624c611a13ad720ec5593df5cccf04afef21bc1 /arch | |
parent | 0d4ee88d92884c661fcafd5576da243aa943dc24 (diff) |
KVM: PPC: Book3S: Use new mutex to synchronize access to rtas token list
Currently the Book 3S KVM code uses kvm->lock to synchronize access
to the kvm->arch.rtas_tokens list. Because this list is scanned
inside kvmppc_rtas_hcall(), which is called with the vcpu mutex held,
taking kvm->lock cause a lock inversion problem, which could lead to
a deadlock.
To fix this, we add a new mutex, kvm->arch.rtas_token_lock, which nests
inside the vcpu mutexes, and use that instead of kvm->lock when
accessing the rtas token list.
This removes the lockdep_assert_held() in kvmppc_rtas_tokens_free().
At this point we don't hold the new mutex, but that is OK because
kvmppc_rtas_tokens_free() is only called when the whole VM is being
destroyed, and at that point nothing can be looking up a token in
the list.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/powerpc/include/asm/kvm_host.h | 1 | ||||
-rw-r--r-- | arch/powerpc/kvm/book3s.c | 1 | ||||
-rw-r--r-- | arch/powerpc/kvm/book3s_rtas.c | 14 |
3 files changed, 8 insertions, 8 deletions
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 26b3ce487ddc..d10df677c452 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -309,6 +309,7 @@ struct kvm_arch { #ifdef CONFIG_PPC_BOOK3S_64 struct list_head spapr_tce_tables; struct list_head rtas_tokens; + struct mutex rtas_token_lock; DECLARE_BITMAP(enabled_hcalls, MAX_HCALL_OPCODE/4 + 1); #endif #ifdef CONFIG_KVM_MPIC diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c index 61a212d0daf0..ac5664845aca 100644 --- a/arch/powerpc/kvm/book3s.c +++ b/arch/powerpc/kvm/book3s.c @@ -902,6 +902,7 @@ int kvmppc_core_init_vm(struct kvm *kvm) #ifdef CONFIG_PPC64 INIT_LIST_HEAD_RCU(&kvm->arch.spapr_tce_tables); INIT_LIST_HEAD(&kvm->arch.rtas_tokens); + mutex_init(&kvm->arch.rtas_token_lock); #endif return kvm->arch.kvm_ops->init_vm(kvm); diff --git a/arch/powerpc/kvm/book3s_rtas.c b/arch/powerpc/kvm/book3s_rtas.c index 4e178c4c1ea5..b7ae3dfbf00e 100644 --- a/arch/powerpc/kvm/book3s_rtas.c +++ b/arch/powerpc/kvm/book3s_rtas.c @@ -146,7 +146,7 @@ static int rtas_token_undefine(struct kvm *kvm, char *name) { struct rtas_token_definition *d, *tmp; - lockdep_assert_held(&kvm->lock); + lockdep_assert_held(&kvm->arch.rtas_token_lock); list_for_each_entry_safe(d, tmp, &kvm->arch.rtas_tokens, list) { if (rtas_name_matches(d->handler->name, name)) { @@ -167,7 +167,7 @@ static int rtas_token_define(struct kvm *kvm, char *name, u64 token) bool found; int i; - lockdep_assert_held(&kvm->lock); + lockdep_assert_held(&kvm->arch.rtas_token_lock); list_for_each_entry(d, &kvm->arch.rtas_tokens, list) { if (d->token == token) @@ -206,14 +206,14 @@ int kvm_vm_ioctl_rtas_define_token(struct kvm *kvm, void __user *argp) if (copy_from_user(&args, argp, sizeof(args))) return -EFAULT; - mutex_lock(&kvm->lock); + mutex_lock(&kvm->arch.rtas_token_lock); if (args.token) rc = rtas_token_define(kvm, args.name, args.token); else rc = rtas_token_undefine(kvm, args.name); - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->arch.rtas_token_lock); return rc; } @@ -245,7 +245,7 @@ int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu) orig_rets = args.rets; args.rets = &args.args[be32_to_cpu(args.nargs)]; - mutex_lock(&vcpu->kvm->lock); + mutex_lock(&vcpu->kvm->arch.rtas_token_lock); rc = -ENOENT; list_for_each_entry(d, &vcpu->kvm->arch.rtas_tokens, list) { @@ -256,7 +256,7 @@ int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu) } } - mutex_unlock(&vcpu->kvm->lock); + mutex_unlock(&vcpu->kvm->arch.rtas_token_lock); if (rc == 0) { args.rets = orig_rets; @@ -282,8 +282,6 @@ void kvmppc_rtas_tokens_free(struct kvm *kvm) { struct rtas_token_definition *d, *tmp; - lockdep_assert_held(&kvm->lock); - list_for_each_entry_safe(d, tmp, &kvm->arch.rtas_tokens, list) { list_del(&d->list); kfree(d); |