[GIT PULL 4/4] KVM: s390: pci: register pci hooks without interpretation

Janosch Frank
2022-09-23T12:10:41Z

The kvm registration hooks must be registered even if the facilities
necessary for zPCI interpretation are unavailable, as vfio-pci-zdev will
expect to use the hooks regardless.
This fixes an issue where vfio-pci-zdev will fail its open function
because of a missing kvm_register when running on hardware that does not
support zPCI interpretation.

Fixes: ca922fecda6c ("KVM: s390: pci: Hook to access KVM lowlevel from VFIO")
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Link: https://lore.kernel.org/r/20220920193025.135655-1-mjrosato@linux.ibm.com
Message-Id: <20220920193025.135655-1-mjrosato@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
arch/s390/kvm/kvm-s390.c | 4 ++--
arch/s390/kvm/pci.c | 14 +++++++++++---
2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index edfd4bbd0cba..b7ef0b71014d 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -505,7 +505,7 @@ int kvm_arch_init(void *opaque)
goto out;
}

- if (kvm_s390_pci_interp_allowed()) {
+ if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM)) {
rc = kvm_s390_pci_init();
if (rc) {
pr_err("Unable to allocate AIFT for PCI\n");
@@ -527,7 +527,7 @@ int kvm_arch_init(void *opaque)
void kvm_arch_exit(void)
{
kvm_s390_gib_destroy();
- if (kvm_s390_pci_interp_allowed())
+ if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM))
kvm_s390_pci_exit();
debug_unregister(kvm_s390_dbf);
debug_unregister(kvm_s390_dbf_uv);
diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
index 90aaba80696a..c50c1645c0ae 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -672,23 +672,31 @@ int kvm_s390_pci_zpci_op(struct kvm *kvm, struct kvm_s390_zpci_op *args)

int kvm_s390_pci_init(void)
{
+ zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
+ zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;
+
+ if (!kvm_s390_pci_interp_allowed())
+ return 0;
+
aift = kzalloc(sizeof(struct zpci_aift), GFP_KERNEL);
if (!aift)
return -ENOMEM;

spin_lock_init(&aift->gait_lock);
mutex_init(&aift->aift_lock);
- zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
- zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;

return 0;
}

void kvm_s390_pci_exit(void)
{
- mutex_destroy(&aift->aift_lock);
zpci_kvm_hook.kvm_register = NULL;
zpci_kvm_hook.kvm_unregister = NULL;

+ if (!kvm_s390_pci_interp_allowed())
+ return;
+
+ mutex_destroy(&aift->aift_lock);
+
kfree(aift);
}
--
2.37.3