[PATCH v2] KVM: s390: pci: Hook to access KVM lowlevel from VFIO

[PATCH v2] KVM: s390: pci: Hook to access KVM lowlevel from VFIO

[Pierre Morel]

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>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Fixes: 09340b2fca007 ("KVM: s390: pci: add routines to start/stop interpretive execution")
Cc: <stable@vger.kernel.org>
---
 arch/s390/include/asm/kvm_host.h | 17 ++++++-----------
 arch/s390/kvm/pci.c              | 12 ++++++++----
 arch/s390/pci/Makefile           |  2 +-
 arch/s390/pci/pci_kvm_hook.c     | 11 +++++++++++
 drivers/vfio/pci/vfio_pci_zdev.c |  8 ++++++--
 5 files changed, 32 insertions(+), 18 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..bb8c335d17b9 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;
 }
@@ -685,6 +687,8 @@ int kvm_s390_pci_init(void)
 void kvm_s390_pci_exit(void)
 {
 	mutex_destroy(&aift->aift_lock);
+	zpci_kvm_hook.kvm_register = NULL;
+	zpci_kvm_hook.kvm_unregister = NULL;
 
 	kfree(aift);
 }
diff --git a/arch/s390/pci/Makefile b/arch/s390/pci/Makefile
index bf557a1b789c..5ae31ca9dd44 100644
--- a/arch/s390/pci/Makefile
+++ b/arch/s390/pci/Makefile
@@ -5,5 +5,5 @@
 
 obj-$(CONFIG_PCI)	+= pci.o pci_irq.o pci_dma.o pci_clp.o pci_sysfs.o \
 			   pci_event.o pci_debug.o pci_insn.o pci_mmio.o \
-			   pci_bus.o
+			   pci_bus.o pci_kvm_hook.o
 obj-$(CONFIG_PCI_IOV)	+= pci_iov.o
diff --git a/arch/s390/pci/pci_kvm_hook.c b/arch/s390/pci/pci_kvm_hook.c
new file mode 100644
index 000000000000..ff34baf50a3e
--- /dev/null
+++ b/arch/s390/pci/pci_kvm_hook.c
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VFIO ZPCI devices support
+ *
+ * Copyright (C) IBM Corp. 2022.  All rights reserved.
+ *	Author(s): Pierre Morel <pmorel@linux.ibm.com>
+ */
+#include <linux/kvm_host.h>
+
+struct zpci_kvm_hook zpci_kvm_hook;
+EXPORT_SYMBOL_GPL(zpci_kvm_hook);
diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
index e163aa9f6144..0cbdcd14f1c8 100644
--- a/drivers/vfio/pci/vfio_pci_zdev.c
+++ b/drivers/vfio/pci/vfio_pci_zdev.c
@@ -151,7 +151,10 @@ int vfio_pci_zdev_open_device(struct vfio_pci_core_device *vdev)
 	if (!vdev->vdev.kvm)
 		return 0;
 
-	return kvm_s390_pci_register_kvm(zdev, vdev->vdev.kvm);
+	if (zpci_kvm_hook.kvm_register)
+		return zpci_kvm_hook.kvm_register(zdev, vdev->vdev.kvm);
+
+	return -ENOENT;
 }
 
 void vfio_pci_zdev_close_device(struct vfio_pci_core_device *vdev)
@@ -161,5 +164,6 @@ void vfio_pci_zdev_close_device(struct vfio_pci_core_device *vdev)
 	if (!zdev || !vdev->vdev.kvm)
 		return;
 
-	kvm_s390_pci_unregister_kvm(zdev);
+	if (zpci_kvm_hook.kvm_unregister)
+		zpci_kvm_hook.kvm_unregister(zdev);
 }
-- 
2.31.1

Re: [PATCH v2] KVM: s390: pci: Hook to access KVM lowlevel from VFIO

[Randy Dunlap]

On 8/19/22 05:29, 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>
> Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
> Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> Fixes: 09340b2fca007 ("KVM: s390: pci: add routines to start/stop interpretive execution")
> Cc: <stable@vger.kernel.org>

Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested

Thanks.

> ---
>  arch/s390/include/asm/kvm_host.h | 17 ++++++-----------
>  arch/s390/kvm/pci.c              | 12 ++++++++----
>  arch/s390/pci/Makefile           |  2 +-
>  arch/s390/pci/pci_kvm_hook.c     | 11 +++++++++++
>  drivers/vfio/pci/vfio_pci_zdev.c |  8 ++++++--
>  5 files changed, 32 insertions(+), 18 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..bb8c335d17b9 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;
>  }
> @@ -685,6 +687,8 @@ int kvm_s390_pci_init(void)
>  void kvm_s390_pci_exit(void)
>  {
>  	mutex_destroy(&aift->aift_lock);
> +	zpci_kvm_hook.kvm_register = NULL;
> +	zpci_kvm_hook.kvm_unregister = NULL;
>  
>  	kfree(aift);
>  }
> diff --git a/arch/s390/pci/Makefile b/arch/s390/pci/Makefile
> index bf557a1b789c..5ae31ca9dd44 100644
> --- a/arch/s390/pci/Makefile
> +++ b/arch/s390/pci/Makefile
> @@ -5,5 +5,5 @@
>  
>  obj-$(CONFIG_PCI)	+= pci.o pci_irq.o pci_dma.o pci_clp.o pci_sysfs.o \
>  			   pci_event.o pci_debug.o pci_insn.o pci_mmio.o \
> -			   pci_bus.o
> +			   pci_bus.o pci_kvm_hook.o
>  obj-$(CONFIG_PCI_IOV)	+= pci_iov.o
> diff --git a/arch/s390/pci/pci_kvm_hook.c b/arch/s390/pci/pci_kvm_hook.c
> new file mode 100644
> index 000000000000..ff34baf50a3e
> --- /dev/null
> +++ b/arch/s390/pci/pci_kvm_hook.c
> @@ -0,0 +1,11 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * VFIO ZPCI devices support
> + *
> + * Copyright (C) IBM Corp. 2022.  All rights reserved.
> + *	Author(s): Pierre Morel <pmorel@linux.ibm.com>
> + */
> +#include <linux/kvm_host.h>
> +
> +struct zpci_kvm_hook zpci_kvm_hook;
> +EXPORT_SYMBOL_GPL(zpci_kvm_hook);
> diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
> index e163aa9f6144..0cbdcd14f1c8 100644
> --- a/drivers/vfio/pci/vfio_pci_zdev.c
> +++ b/drivers/vfio/pci/vfio_pci_zdev.c
> @@ -151,7 +151,10 @@ int vfio_pci_zdev_open_device(struct vfio_pci_core_device *vdev)
>  	if (!vdev->vdev.kvm)
>  		return 0;
>  
> -	return kvm_s390_pci_register_kvm(zdev, vdev->vdev.kvm);
> +	if (zpci_kvm_hook.kvm_register)
> +		return zpci_kvm_hook.kvm_register(zdev, vdev->vdev.kvm);
> +
> +	return -ENOENT;
>  }
>  
>  void vfio_pci_zdev_close_device(struct vfio_pci_core_device *vdev)
> @@ -161,5 +164,6 @@ void vfio_pci_zdev_close_device(struct vfio_pci_core_device *vdev)
>  	if (!zdev || !vdev->vdev.kvm)
>  		return;
>  
> -	kvm_s390_pci_unregister_kvm(zdev);
> +	if (zpci_kvm_hook.kvm_unregister)
> +		zpci_kvm_hook.kvm_unregister(zdev);
>  }

-- 
~Randy

Re: [PATCH v2] KVM: s390: pci: Hook to access KVM lowlevel from VFIO

[Pierre Morel]

On 8/19/22 23:10, Randy Dunlap wrote:
> 
> 
> On 8/19/22 05:29, 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>
>> Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
>> Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> Fixes: 09340b2fca007 ("KVM: s390: pci: add routines to start/stop interpretive execution")
>> Cc: <stable@vger.kernel.org>
> 
> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
> 
> Thanks.

Thanks Randy,

Regards,
Pierre


> 
>> ---
>>   arch/s390/include/asm/kvm_host.h | 17 ++++++-----------
>>   arch/s390/kvm/pci.c              | 12 ++++++++----
>>   arch/s390/pci/Makefile           |  2 +-
>>   arch/s390/pci/pci_kvm_hook.c     | 11 +++++++++++
>>   drivers/vfio/pci/vfio_pci_zdev.c |  8 ++++++--
>>   5 files changed, 32 insertions(+), 18 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..bb8c335d17b9 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;
>>   }
>> @@ -685,6 +687,8 @@ int kvm_s390_pci_init(void)
>>   void kvm_s390_pci_exit(void)
>>   {
>>   	mutex_destroy(&aift->aift_lock);
>> +	zpci_kvm_hook.kvm_register = NULL;
>> +	zpci_kvm_hook.kvm_unregister = NULL;
>>   
>>   	kfree(aift);
>>   }
>> diff --git a/arch/s390/pci/Makefile b/arch/s390/pci/Makefile
>> index bf557a1b789c..5ae31ca9dd44 100644
>> --- a/arch/s390/pci/Makefile
>> +++ b/arch/s390/pci/Makefile
>> @@ -5,5 +5,5 @@
>>   
>>   obj-$(CONFIG_PCI)	+= pci.o pci_irq.o pci_dma.o pci_clp.o pci_sysfs.o \
>>   			   pci_event.o pci_debug.o pci_insn.o pci_mmio.o \
>> -			   pci_bus.o
>> +			   pci_bus.o pci_kvm_hook.o
>>   obj-$(CONFIG_PCI_IOV)	+= pci_iov.o
>> diff --git a/arch/s390/pci/pci_kvm_hook.c b/arch/s390/pci/pci_kvm_hook.c
>> new file mode 100644
>> index 000000000000..ff34baf50a3e
>> --- /dev/null
>> +++ b/arch/s390/pci/pci_kvm_hook.c
>> @@ -0,0 +1,11 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * VFIO ZPCI devices support
>> + *
>> + * Copyright (C) IBM Corp. 2022.  All rights reserved.
>> + *	Author(s): Pierre Morel <pmorel@linux.ibm.com>
>> + */
>> +#include <linux/kvm_host.h>
>> +
>> +struct zpci_kvm_hook zpci_kvm_hook;
>> +EXPORT_SYMBOL_GPL(zpci_kvm_hook);
>> diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
>> index e163aa9f6144..0cbdcd14f1c8 100644
>> --- a/drivers/vfio/pci/vfio_pci_zdev.c
>> +++ b/drivers/vfio/pci/vfio_pci_zdev.c
>> @@ -151,7 +151,10 @@ int vfio_pci_zdev_open_device(struct vfio_pci_core_device *vdev)
>>   	if (!vdev->vdev.kvm)
>>   		return 0;
>>   
>> -	return kvm_s390_pci_register_kvm(zdev, vdev->vdev.kvm);
>> +	if (zpci_kvm_hook.kvm_register)
>> +		return zpci_kvm_hook.kvm_register(zdev, vdev->vdev.kvm);
>> +
>> +	return -ENOENT;
>>   }
>>   
>>   void vfio_pci_zdev_close_device(struct vfio_pci_core_device *vdev)
>> @@ -161,5 +164,6 @@ void vfio_pci_zdev_close_device(struct vfio_pci_core_device *vdev)
>>   	if (!zdev || !vdev->vdev.kvm)
>>   		return;
>>   
>> -	kvm_s390_pci_unregister_kvm(zdev);
>> +	if (zpci_kvm_hook.kvm_unregister)
>> +		zpci_kvm_hook.kvm_unregister(zdev);
>>   }
> 

-- 
Pierre Morel
IBM Lab Boeblingen

Re: [PATCH v2] KVM: s390: pci: Hook to access KVM lowlevel from VFIO

[Janosch Frank]

On 8/19/22 14:29, 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>
> Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
> Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> Fixes: 09340b2fca007 ("KVM: s390: pci: add routines to start/stop interpretive execution")
> Cc: <stable@vger.kernel.org>

Acked-by: Janosch Frank <frankja@linux.ibm.com>

@Niklas @Matt: Since the patches that introduced the PCI interpretation 
went via the KVM tree I'll also move this patch via the KVM tree.

Re: [PATCH v2] KVM: s390: pci: Hook to access KVM lowlevel from VFIO

[Niklas Schnelle]

On Tue, 2022-08-23 at 09:25 +0200, Janosch Frank wrote:
> On 8/19/22 14:29, 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>
> > Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
> > Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
> > Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> > Fixes: 09340b2fca007 ("KVM: s390: pci: add routines to start/stop interpretive execution")
> > Cc: <stable@vger.kernel.org>
> 
> Acked-by: Janosch Frank <frankja@linux.ibm.com>
> 
> @Niklas @Matt: Since the patches that introduced the PCI interpretation 
> went via the KVM tree I'll also move this patch via the KVM tree.

Sounds good, thanks.