[PATCH v3 25/30] vfio-pci/zdev: wire up zPCI interpretive execution support

[Matthew Rosato <mjrosato@linux.ibm.com>]

Introduce support for VFIO_DEVICE_FEATURE_ZPCI_INTERP, which is a new
VFIO_DEVICE_FEATURE ioctl.  This interface is used to indicate that an
s390x vfio-pci device wishes to enable/disable zPCI interpretive
execution, which allows zPCI instructions to be executed directly by
underlying firmware without KVM involvement.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
 arch/s390/include/asm/kvm_pci.h  |  1 +
 drivers/vfio/pci/vfio_pci_core.c |  2 +
 drivers/vfio/pci/vfio_pci_zdev.c | 73 ++++++++++++++++++++++++++++++++
 include/linux/vfio_pci_core.h    | 10 +++++
 include/uapi/linux/vfio.h        |  7 +++
 include/uapi/linux/vfio_zdev.h   | 15 +++++++
 6 files changed, 108 insertions(+)

diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
index 16290b4cf2a6..8f7d371e3e59 100644
--- a/arch/s390/include/asm/kvm_pci.h
+++ b/arch/s390/include/asm/kvm_pci.h
@@ -34,6 +34,7 @@ struct kvm_zdev {
 	struct kvm_zdev_ioat ioat;
 	struct zpci_fib fib;
 	struct notifier_block nb;
+	bool interpretation;
 };
 
 int kvm_s390_pci_dev_open(struct zpci_dev *zdev);
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index fc57d4d0abbe..2b2d64a2190c 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -1172,6 +1172,8 @@ long vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
 			mutex_unlock(&vdev->vf_token->lock);
 
 			return 0;
+		case VFIO_DEVICE_FEATURE_ZPCI_INTERP:
+			return vfio_pci_zdev_feat_interp(vdev, feature, arg);
 		default:
 			return -ENOTTY;
 		}
diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
index 9f8284499111..71cc1eb8085f 100644
--- a/drivers/vfio/pci/vfio_pci_zdev.c
+++ b/drivers/vfio/pci/vfio_pci_zdev.c
@@ -54,6 +54,10 @@ static int zpci_group_cap(struct zpci_dev *zdev, struct vfio_info_cap *caps)
 		.version = zdev->version
 	};
 
+	/* Some values are different for interpreted devices */
+	if (zdev->kzdev && zdev->kzdev->interpretation)
+		cap.maxstbl = zdev->maxstbl;
+
 	return vfio_info_add_capability(caps, &cap.header, sizeof(cap));
 }
 
@@ -138,6 +142,67 @@ int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,
 	return ret;
 }
 
+int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
+			      struct vfio_device_feature feature,
+			      unsigned long arg)
+{
+	struct zpci_dev *zdev = to_zpci(vdev->pdev);
+	struct vfio_device_zpci_interp *data;
+	struct vfio_device_feature *feat;
+	unsigned long minsz;
+	int size, rc;
+
+	if (!zdev || !zdev->kzdev)
+		return -EINVAL;
+
+	/* If PROBE specified, return probe results immediately */
+	if (feature.flags & VFIO_DEVICE_FEATURE_PROBE)
+		return kvm_s390_pci_interp_probe(zdev);
+
+	size = sizeof(*feat) + sizeof(*data);
+	feat = kzalloc(size, GFP_KERNEL);
+	if (!feat)
+		return -ENOMEM;
+
+	data = (struct vfio_device_zpci_interp *)&feat->data;
+	minsz = offsetofend(struct vfio_device_feature, flags);
+
+	if (feature.argsz < minsz + sizeof(*data))
+		return -EINVAL;
+
+	/* Get the rest of the payload for GET/SET */
+	rc = copy_from_user(data, (void __user *)(arg + minsz),
+			    sizeof(*data));
+	if (rc)
+		rc = -EINVAL;
+
+	if (feature.flags & VFIO_DEVICE_FEATURE_GET) {
+		if (zdev->gisa != 0)
+			data->flags = VFIO_DEVICE_ZPCI_FLAG_INTERP;
+		else
+			data->flags = 0;
+		data->fh = zdev->fh;
+		/* userspace is using host fh, give interpreted clp values */
+		zdev->kzdev->interpretation = true;
+
+		if (copy_to_user((void __user *)arg, feat, size))
+			rc = -EFAULT;
+	} else if (feature.flags & VFIO_DEVICE_FEATURE_SET) {
+		if (data->flags == VFIO_DEVICE_ZPCI_FLAG_INTERP)
+			rc = kvm_s390_pci_interp_enable(zdev);
+		else if (data->flags == 0)
+			rc = kvm_s390_pci_interp_disable(zdev, false);
+		else
+			rc = -EINVAL;
+	} else {
+		/* Neither GET nor SET were specified */
+		rc = -EINVAL;
+	}
+
+	kfree(feat);
+	return rc;
+}
+
 static int vfio_pci_zdev_group_notifier(struct notifier_block *nb,
 					unsigned long action, void *data)
 {
@@ -164,6 +229,7 @@ void vfio_pci_zdev_open(struct vfio_pci_core_device *vdev)
 		return;
 
 	zdev->kzdev->nb.notifier_call = vfio_pci_zdev_group_notifier;
+	zdev->kzdev->interpretation = false;
 
 	if (vfio_register_notifier(vdev->vdev.dev, VFIO_GROUP_NOTIFY,
 				   &events, &zdev->kzdev->nb))
@@ -180,5 +246,12 @@ void vfio_pci_zdev_release(struct vfio_pci_core_device *vdev)
 	vfio_unregister_notifier(vdev->vdev.dev, VFIO_GROUP_NOTIFY,
 				 &zdev->kzdev->nb);
 
+	/*
+	 * If the device was using interpretation, don't trust that userspace
+	 * did the appropriate cleanup
+	 */
+	if (zdev->gisa != 0)
+		kvm_s390_pci_interp_disable(zdev, true);
+
 	kvm_s390_pci_dev_release(zdev);
 }
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index 05287f8ac855..0db2b1051931 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -198,6 +198,9 @@ static inline int vfio_pci_igd_init(struct vfio_pci_core_device *vdev)
 #ifdef CONFIG_VFIO_PCI_ZDEV
 extern int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,
 				       struct vfio_info_cap *caps);
+int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
+			      struct vfio_device_feature feature,
+			      unsigned long arg);
 void vfio_pci_zdev_open(struct vfio_pci_core_device *vdev);
 void vfio_pci_zdev_release(struct vfio_pci_core_device *vdev);
 #else
@@ -207,6 +210,13 @@ static inline int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,
 	return -ENODEV;
 }
 
+static inline int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
+					    struct vfio_device_feature feature,
+					    unsigned long arg)
+{
+	return -ENOTTY;
+}
+
 static inline void vfio_pci_zdev_open(struct vfio_pci_core_device *vdev)
 {
 }
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index ef33ea002b0b..b9a75485b8e7 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1002,6 +1002,13 @@ struct vfio_device_feature {
  */
 #define VFIO_DEVICE_FEATURE_PCI_VF_TOKEN	(0)
 
+/*
+ * Provide support for enabling interpretation of zPCI instructions.  This
+ * feature is only valid for s390x PCI devices.  Data provided when setting
+ * and getting this feature is futher described in vfio_zdev.h
+ */
+#define VFIO_DEVICE_FEATURE_ZPCI_INTERP		(1)
+
 /* -------- API for Type1 VFIO IOMMU -------- */
 
 /**
diff --git a/include/uapi/linux/vfio_zdev.h b/include/uapi/linux/vfio_zdev.h
index b4309397b6b2..575f0410dc66 100644
--- a/include/uapi/linux/vfio_zdev.h
+++ b/include/uapi/linux/vfio_zdev.h
@@ -75,4 +75,19 @@ struct vfio_device_info_cap_zpci_pfip {
 	__u8 pfip[];
 };
 
+/**
+ * VFIO_DEVICE_FEATURE_ZPCI_INTERP
+ *
+ * This feature is used for enabling zPCI instruction interpretation for a
+ * device.  No data is provided when setting this feature.  When getting
+ * this feature, the following structure is provided which details whether
+ * or not interpretation is active and provides the guest with host device
+ * information necessary to enable interpretation.
+ */
+struct vfio_device_zpci_interp {
+	__u64 flags;
+#define VFIO_DEVICE_ZPCI_FLAG_INTERP 1
+	__u32 fh;		/* Host device function handle */
+};
+
 #endif
-- 
2.27.0