Skip to contentSkip to conversation

FAILED: patch "[PATCH] KVM: s390: pci: Hook to access KVM lowlevel from VFIO" failed to apply to 5.19-stable tree

PATCH [email protected] 1 participant 1 message Sep 6, 2022

Subsystems (6)
Stable branch s390 VFIO driver KVM s390 +2 more subsystems
lore
Share & tools
lore

[email protected]

author maintainer
#0 lore raw

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 <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ca922fecda6caa5162409406dc3b663062d75089 Mon Sep 17 00:00:00 2001
From: Pierre Morel <[email protected]>
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 <[email protected]>
Reported-by kernel test robot <[email protected]>
Reviewed-by Matthew Rosato <[email protected]>
Reviewed-by Niklas Schnelle <[email protected]>
Signed-off-by Pierre Morel <[email protected]>
Fixes 09340b2fca007 ("KVM: s390: pci: add routines to start/stop interpretive execution")
Cc <[email protected]>
Acked-by Janosch Frank <[email protected]>
Acked-by Randy Dunlap <[email protected]> # build-tested
Link https://lore.kernel.org/r/[email protected] open here

Message-Id: <[email protected]>

Signed-off-by Janosch Frank <[email protected]>
arch/s390/include/asm/kvm_host.h +6 -11
index f39092e0ceaa..b1e98a9ed152 100644
@@ -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
index 4946fb7757d6..bb8c335d17b9 100644
@@ -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
index bf557a1b789c..5ae31ca9dd44 100644
@@ -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 new file +11 -0
new file mode 100644
index 000000000000..ff34baf50a3e
@@ -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 <[email protected]>
+ */
+#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
index e163aa9f6144..0cbdcd14f1c8 100644
@@ -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);
 }