[PATCH v3 26/30] vfio-pci/zdev: wire up zPCI adapter interrupt forwarding support

Matthew Rosato
2022-02-04T21:17:55Z

Introduce support for VFIO_DEVICE_FEATURE_ZPCI_AIF, 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 adapter interrupt
forwarding, which allows underlying firmware to deliver interrupts
directly to the associated kvm guest.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
arch/s390/include/asm/kvm_pci.h | 2 +
drivers/vfio/pci/vfio_pci_core.c | 2 +
drivers/vfio/pci/vfio_pci_zdev.c | 93 +++++++++++++++++++++++++++++++-
include/linux/vfio_pci_core.h | 10 ++++
include/uapi/linux/vfio.h | 7 +++
include/uapi/linux/vfio_zdev.h | 20 +++++++
6 files changed, 133 insertions(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
index 8f7d371e3e59..93b61e61dc7f 100644
--- a/arch/s390/include/asm/kvm_pci.h
+++ b/arch/s390/include/asm/kvm_pci.h
@@ -35,6 +35,8 @@ struct kvm_zdev {
struct zpci_fib fib;
struct notifier_block nb;
bool interpretation;
+ bool aif_float; /* Enabled for floating interrupt assist */
+ bool aif_host; /* Require host delivery */
};

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 2b2d64a2190c..01658de660bd 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -1174,6 +1174,8 @@ long vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
return 0;
case VFIO_DEVICE_FEATURE_ZPCI_INTERP:
return vfio_pci_zdev_feat_interp(vdev, feature, arg);
+ case VFIO_DEVICE_FEATURE_ZPCI_AIF:
+ return vfio_pci_zdev_feat_aif(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 71cc1eb8085f..74508bdc5f88 100644
--- a/drivers/vfio/pci/vfio_pci_zdev.c
+++ b/drivers/vfio/pci/vfio_pci_zdev.c
@@ -13,6 +13,7 @@
#include <linux/vfio_zdev.h>
#include <asm/pci_clp.h>
#include <asm/pci_io.h>
+#include <asm/pci_insn.h>
#include <asm/kvm_pci.h>

#include <linux/vfio_pci_core.h>
@@ -203,6 +204,94 @@ int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
return rc;
}

+int vfio_pci_zdev_feat_aif(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_aif *data;
+ struct vfio_device_feature *feat;
+ unsigned long minsz;
+ int size, rc = 0;
+
+ if (!zdev || !zdev->kzdev)
+ return -EINVAL;
+
+ /* If PROBE specified, return probe results immediately */
+ if (feature.flags & VFIO_DEVICE_FEATURE_PROBE)
+ return kvm_s390_pci_aif_probe(zdev);
+
+ size = sizeof(*feat) + sizeof(*data);
+ feat = kzalloc(size, GFP_KERNEL);
+ if (!feat)
+ return -ENOMEM;
+
+ data = (struct vfio_device_zpci_aif *)&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->kzdev->aif_float)
+ data->flags = VFIO_DEVICE_ZPCI_FLAG_AIF_FLOAT;
+ if (zdev->kzdev->aif_host)
+ data->flags |= VFIO_DEVICE_ZPCI_FLAG_AIF_HOST;
+
+ 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_AIF_FLOAT) {
+ /* create a guest fib */
+ struct zpci_fib fib;
+
+ fib.fmt0.aibv = data->ibv;
+ fib.fmt0.isc = data->isc;
+ fib.fmt0.noi = data->noi;
+ if (data->sb != 0) {
+ fib.fmt0.aisb = data->sb;
+ fib.fmt0.aisbo = data->sbo;
+ fib.fmt0.sum = 1;
+ } else {
+ fib.fmt0.aisb = 0;
+ fib.fmt0.aisbo = 0;
+ fib.fmt0.sum = 0;
+ }
+ if (data->flags & VFIO_DEVICE_ZPCI_FLAG_AIF_HOST) {
+ rc = kvm_s390_pci_aif_enable(zdev, &fib, false);
+ if (!rc) {
+ zdev->kzdev->aif_float = true;
+ zdev->kzdev->aif_host = true;
+ }
+ } else {
+ rc = kvm_s390_pci_aif_enable(zdev, &fib, true);
+ if (!rc)
+ zdev->kzdev->aif_float = true;
+ }
+ } else if (data->flags == 0) {
+ rc = kvm_s390_pci_aif_disable(zdev, false);
+ if (!rc) {
+ zdev->kzdev->aif_float = false;
+ zdev->kzdev->aif_host = 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)
{
@@ -250,8 +339,10 @@ void vfio_pci_zdev_release(struct vfio_pci_core_device *vdev)
* If the device was using interpretation, don't trust that userspace
* did the appropriate cleanup
*/
- if (zdev->gisa != 0)
+ if (zdev->gisa != 0) {
+ kvm_s390_pci_aif_disable(zdev, true);
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 0db2b1051931..7ec5e82e7933 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -201,6 +201,9 @@ extern int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,
int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
struct vfio_device_feature feature,
unsigned long arg);
+int vfio_pci_zdev_feat_aif(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
@@ -217,6 +220,13 @@ static inline int vfio_pci_zdev_feat_interp(struct vfio_pci_core_device *vdev,
return -ENOTTY;
}

+static inline int vfio_pci_zdev_feat_aif(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 b9a75485b8e7..fe3bfd99bf50 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1009,6 +1009,13 @@ struct vfio_device_feature {
*/
#define VFIO_DEVICE_FEATURE_ZPCI_INTERP (1)

+/*
+ * Provide support for enbaling adapter interruption forwarding for zPCI
+ * devices. This feature is only valid for s390x PCI devices. Data provided
+ * when setting and getting this feature is further described in vfio_zdev.h
+ */
+#define VFIO_DEVICE_FEATURE_ZPCI_AIF (2)
+
/* -------- API for Type1 VFIO IOMMU -------- */

/**
diff --git a/include/uapi/linux/vfio_zdev.h b/include/uapi/linux/vfio_zdev.h
index 575f0410dc66..09f413dfb1c3 100644
--- a/include/uapi/linux/vfio_zdev.h
+++ b/include/uapi/linux/vfio_zdev.h
@@ -90,4 +90,24 @@ struct vfio_device_zpci_interp {
__u32 fh; /* Host device function handle */
};

+/**
+ * VFIO_DEVICE_FEATURE_ZPCI_AIF
+ *
+ * This feature is used for enabling forwarding of adapter interrupts directly
+ * from firmware to the guest. When setting this feature, the flags indicate
+ * whether to enable/disable the feature and the structure defined below is
+ * used to setup the forwarding structures. When getting this feature, only
+ * the flags are used to indicate the current state.
+ */
+struct vfio_device_zpci_aif {
+ __u64 flags;
+#define VFIO_DEVICE_ZPCI_FLAG_AIF_FLOAT 1 /* Enable floating interrupts */
+#define VFIO_DEVICE_ZPCI_FLAG_AIF_HOST 2 /* Force host delivery */
+ __u64 ibv; /* Address of guest interrupt bit vector */
+ __u64 sb; /* Address of guest summary bit */
+ __u32 noi; /* Number of interrupts */
+ __u8 isc; /* Guest interrupt subclass */
+ __u8 sbo; /* Offset of guest summary bit vector */
+};
+
#endif
--
2.27.0