diff options
author | Tony Krowiak <akrowiak@linux.ibm.com> | 2021-08-23 17:20:47 -0400 |
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committer | Alex Williamson <alex.williamson@redhat.com> | 2021-08-24 12:14:05 -0600 |
commit | 86956e70761b3292156d668e87126844334dd71b (patch) | |
tree | 1b3ab8ab7490afc04134d5d0ab7d4b4b240a820a /arch/s390 | |
parent | 1e753732bda6dcf888ea0b90b2a91ac1c1a0bae9 (diff) | |
download | linux-86956e70761b3292156d668e87126844334dd71b.tar.bz2 |
s390/vfio-ap: replace open coded locks for VFIO_GROUP_NOTIFY_SET_KVM notification
It was pointed out during an unrelated patch review that locks should not
be open coded - i.e., writing the algorithm of a standard lock in a
function instead of using a lock from the standard library. The setting and
testing of a busy flag and sleeping on a wait_event is the same thing
a lock does. The open coded locks are invisible to lockdep, so potential
locking problems are not detected.
This patch removes the open coded locks used during
VFIO_GROUP_NOTIFY_SET_KVM notification. The busy flag
and wait queue were introduced to resolve a possible circular locking
dependency reported by lockdep when starting a secure execution guest
configured with AP adapters and domains. Reversing the order in which
the kvm->lock mutex and matrix_dev->lock mutex are locked resolves the
issue reported by lockdep, thus enabling the removal of the open coded
locks.
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Link: https://lore.kernel.org/r/20210823212047.1476436-3-akrowiak@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'arch/s390')
-rw-r--r-- | arch/s390/kvm/kvm-s390.c | 31 |
1 files changed, 27 insertions, 4 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 5c4f559bcd60..efda0615741f 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -2559,12 +2559,26 @@ static void kvm_s390_set_crycb_format(struct kvm *kvm) kvm->arch.crypto.crycbd |= CRYCB_FORMAT1; } +/* + * kvm_arch_crypto_set_masks + * + * @kvm: pointer to the target guest's KVM struct containing the crypto masks + * to be set. + * @apm: the mask identifying the accessible AP adapters + * @aqm: the mask identifying the accessible AP domains + * @adm: the mask identifying the accessible AP control domains + * + * Set the masks that identify the adapters, domains and control domains to + * which the KVM guest is granted access. + * + * Note: The kvm->lock mutex must be locked by the caller before invoking this + * function. + */ void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm, unsigned long *aqm, unsigned long *adm) { struct kvm_s390_crypto_cb *crycb = kvm->arch.crypto.crycb; - mutex_lock(&kvm->lock); kvm_s390_vcpu_block_all(kvm); switch (kvm->arch.crypto.crycbd & CRYCB_FORMAT_MASK) { @@ -2595,13 +2609,23 @@ void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm, /* recreate the shadow crycb for each vcpu */ kvm_s390_sync_request_broadcast(kvm, KVM_REQ_VSIE_RESTART); kvm_s390_vcpu_unblock_all(kvm); - mutex_unlock(&kvm->lock); } EXPORT_SYMBOL_GPL(kvm_arch_crypto_set_masks); +/* + * kvm_arch_crypto_clear_masks + * + * @kvm: pointer to the target guest's KVM struct containing the crypto masks + * to be cleared. + * + * Clear the masks that identify the adapters, domains and control domains to + * which the KVM guest is granted access. + * + * Note: The kvm->lock mutex must be locked by the caller before invoking this + * function. + */ void kvm_arch_crypto_clear_masks(struct kvm *kvm) { - mutex_lock(&kvm->lock); kvm_s390_vcpu_block_all(kvm); memset(&kvm->arch.crypto.crycb->apcb0, 0, @@ -2613,7 +2637,6 @@ void kvm_arch_crypto_clear_masks(struct kvm *kvm) /* recreate the shadow crycb for each vcpu */ kvm_s390_sync_request_broadcast(kvm, KVM_REQ_VSIE_RESTART); kvm_s390_vcpu_unblock_all(kvm); - mutex_unlock(&kvm->lock); } EXPORT_SYMBOL_GPL(kvm_arch_crypto_clear_masks); |