Messages in this thread | | | Date | Thu, 18 Aug 2022 22:54:56 +0200 | Subject | Re: [PATCH] KVM: s390: pci: Hook to access KVM lowlevel from VFIO | From | Pierre Morel <> |
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On 8/18/22 22:38, Matthew Rosato wrote: > On 8/18/22 12:46 PM, Pierre Morel wrote: >> We have a cross dependency between KVM and VFIO when using >> s390 vfio_pci_zdev extensions for PCI passthrough >> To be able to keep both subsystem modular we add a registering >> hook inside the S390 core code. >> >> This fixes a build problem when VFIO is built-in and KVM is built >> as a module. >> >> Reported-by: Randy Dunlap <rdunlap@infradead.org> >> Reported-by: kernel test robot <lkp@intel.com> >> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com> >> Fixes: 09340b2fca007 ("KVM: s390: pci: add routines to start/stop inter..") >> Cc: <stable@vger.kernel.org> >> --- >> arch/s390/include/asm/kvm_host.h | 17 ++++++----------- >> arch/s390/kvm/pci.c | 10 ++++++---- >> arch/s390/pci/Makefile | 2 ++ >> arch/s390/pci/pci_kvm_hook.c | 11 +++++++++++ >> drivers/vfio/pci/vfio_pci_zdev.c | 8 ++++++-- >> 5 files changed, 31 insertions(+), 17 deletions(-) >> create mode 100644 arch/s390/pci/pci_kvm_hook.c >> >> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h >> index f39092e0ceaa..b1e98a9ed152 100644 >> --- a/arch/s390/include/asm/kvm_host.h >> +++ b/arch/s390/include/asm/kvm_host.h >> @@ -1038,16 +1038,11 @@ static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {} >> #define __KVM_HAVE_ARCH_VM_FREE >> void kvm_arch_free_vm(struct kvm *kvm); >> >> -#ifdef CONFIG_VFIO_PCI_ZDEV_KVM >> -int kvm_s390_pci_register_kvm(struct zpci_dev *zdev, struct kvm *kvm); >> -void kvm_s390_pci_unregister_kvm(struct zpci_dev *zdev); >> -#else >> -static inline int kvm_s390_pci_register_kvm(struct zpci_dev *dev, >> - struct kvm *kvm) >> -{ >> - return -EPERM; >> -} >> -static inline void kvm_s390_pci_unregister_kvm(struct zpci_dev *dev) {} >> -#endif >> +struct zpci_kvm_hook { >> + int (*kvm_register)(void *opaque, struct kvm *kvm); >> + void (*kvm_unregister)(void *opaque); >> +}; >> + >> +extern struct zpci_kvm_hook zpci_kvm_hook; >> >> #endif >> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c >> index 4946fb7757d6..22c025538323 100644 >> --- a/arch/s390/kvm/pci.c >> +++ b/arch/s390/kvm/pci.c >> @@ -431,8 +431,9 @@ static void kvm_s390_pci_dev_release(struct zpci_dev *zdev) >> * available, enable them and let userspace indicate whether or not they will >> * be used (specify SHM bit to disable). >> */ >> -int kvm_s390_pci_register_kvm(struct zpci_dev *zdev, struct kvm *kvm) >> +static int kvm_s390_pci_register_kvm(void *opaque, struct kvm *kvm) >> { >> + struct zpci_dev *zdev = opaque; >> int rc; >> >> if (!zdev) >> @@ -510,10 +511,10 @@ int kvm_s390_pci_register_kvm(struct zpci_dev *zdev, struct kvm *kvm) >> kvm_put_kvm(kvm); >> return rc; >> } >> -EXPORT_SYMBOL_GPL(kvm_s390_pci_register_kvm); >> >> -void kvm_s390_pci_unregister_kvm(struct zpci_dev *zdev) >> +static void kvm_s390_pci_unregister_kvm(void *opaque) >> { >> + struct zpci_dev *zdev = opaque; >> struct kvm *kvm; >> >> if (!zdev) >> @@ -566,7 +567,6 @@ void kvm_s390_pci_unregister_kvm(struct zpci_dev *zdev) >> >> kvm_put_kvm(kvm); >> } >> -EXPORT_SYMBOL_GPL(kvm_s390_pci_unregister_kvm); >> >> void kvm_s390_pci_init_list(struct kvm *kvm) >> { >> @@ -678,6 +678,8 @@ int kvm_s390_pci_init(void) >> >> 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; >> } > > You should also set these to NULL in kvm_s390_pci_exit (which is called from kvm_arch_exit). In practice, the kvm module would need to be loaded again before we have a nonzero vdev->vdev.kvm so it should never be an issue - but we should clean up anyway when the module is removed. > > With that change: > > Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com> >
Yes indeed, will do. Thanks
Pierre
-- Pierre Morel IBM Lab Boeblingen
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