Commit ca922fec authored by Pierre Morel's avatar Pierre Morel Committed by Janosch Frank
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KVM: s390: pci: Hook to access KVM lowlevel from VFIO 



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: default avatarRandy Dunlap <rdunlap@infradead.org>
Reported-by: default avatarkernel test robot <lkp@intel.com>
Reviewed-by: default avatarMatthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: default avatarNiklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: default avatarPierre Morel <pmorel@linux.ibm.com>
Fixes: 09340b2f ("KVM: s390: pci: add routines to start/stop interpretive execution")
Cc: <stable@vger.kernel.org>
Acked-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Link: https://lore.kernel.org/r/20220819122945.9309-1-pmorel@linux.ibm.com


Message-Id: <20220819122945.9309-1-pmorel@linux.ibm.com>
Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
parent b90cb105

arch/s390/include/asm/kvm_host.h

+6 −11
Original line number Diff line number Diff line
@@ -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

arch/s390/kvm/pci.c

+8 −4
Original line number Diff line number Diff line
@@ -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);

}

arch/s390/pci/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/s390/pci/pci_kvm_hook.c

0 → 100644
+11 −0
Original line number Diff line number Diff line 
// 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);

drivers/vfio/pci/vfio_pci_zdev.c

+6 −2
Original line number Diff line number Diff line
@@ -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);

}