The patch below does not apply to the 5.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ca922fecda6caa5162409406dc3b663062d75089 Mon Sep 17 00:00:00 2001 From: Pierre Morel pmorel@linux.ibm.com Date: Fri, 19 Aug 2022 14:29:45 +0200 Subject: [PATCH] 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: 09340b2fca007 ("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
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); }