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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: 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: 09340b2fca ("KVM: s390: pci: add routines to start/stop interpretive execution")
Cc: <stable@vger.kernel.org>
Acked-by: Janosch 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: Janosch Frank <frankja@linux.ibm.com>
This commit is contained in:
Pierre Morel 2022-08-19 14:29:45 +02:00 committed by Janosch Frank
parent b90cb10531
commit ca922fecda
5 changed files with 32 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
arch/s390/include/asm/kvm_host.h
View File

@ -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

12
arch/s390/kvm/pci.c
View File

@ -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 @@ err:
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 @@ out:
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);
}

2
arch/s390/pci/Makefile
View File

@ -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

11
arch/s390/pci/pci_kvm_hook.c Normal file
View File

@ -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);

8
drivers/vfio/pci/vfio_pci_zdev.c
View File

@ -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);
}