diff options
| author | Paul Mackerras <paulus@ozlabs.org> | 2019-05-29 11:54:00 +1000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-06-22 08:15:19 +0200 |
| commit | b376683f6ab16e1dc57800f69a63978a05ddff1f (patch) | |
| tree | b9f75d380e575b1719d0cfba391d507cbe61f04c /arch/powerpc/kvm/book3s.c | |
| parent | 4acce744284ca813169d85773b21a677457ce416 (diff) | |
KVM: PPC: Book3S: Use new mutex to synchronize access to rtas token list
[ Upstream commit 1659e27d2bc1ef47b6d031abe01b467f18cb72d9 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/powerpc/kvm/book3s.c')
| -rw-r--r-- | arch/powerpc/kvm/book3s.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c index 87348e498c89..281f074581a3 100644 --- a/arch/powerpc/kvm/book3s.c +++ b/arch/powerpc/kvm/book3s.c @@ -840,6 +840,7 @@ 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); |