[Qemu-devel] [PATCH v5 4/6] s390x/vfio: ap: Introduce VFIO AP device

[Tony Krowiak <akrowiak@linux.vnet.ibm.com>]

Introduces a VFIO based AP device. The device is defined via
the QEMU command line by specifying:

    -device vfio-ap,sysfsdev=<path-to-mediated-matrix-device>

There may be only one vfio-ap device configured for a guest.

The mediated matrix device is created by the VFIO AP device
driver by writing a UUID to a sysfs attribute file (see
docs/vfio-ap.txt). The mediated matrix device will be named
after the UUID. Symbolic links to the $uuid are created in
many places, so the path to the mediated matrix device $uuid
can be specified in any of the following ways:

/sys/devices/vfio_ap/matrix/$uuid
/sys/devices/vfio_ap/matrix/mdev_supported_types/vfio_ap-passthrough/devices/$uuid
/sys/bus/mdev/devices/$uuid
/sys/bus/mdev/drivers/vfio_mdev/$uuid

When the vfio-ap device is realized, it acquires and opens the
VFIO iommu group to which the mediated matrix device is
bound. This causes a VFIO group notification event to be
signaled. The vfio_ap device driver's group notification
handler will get called at which time the device driver
will configure the the AP devices to which the guest will
be granted access.

Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>
---
 default-configs/s390x-softmmu.mak |    1 +
 hw/vfio/Makefile.objs             |    1 +
 hw/vfio/ap.c                      |  182 +++++++++++++++++++++++++++++++++++++
 include/hw/vfio/vfio-common.h     |    1 +
 4 files changed, 185 insertions(+), 0 deletions(-)
 create mode 100644 hw/vfio/ap.c

diff --git a/default-configs/s390x-softmmu.mak b/default-configs/s390x-softmmu.mak
index 2f4bfe7..0b784b6 100644
--- a/default-configs/s390x-softmmu.mak
+++ b/default-configs/s390x-softmmu.mak
@@ -9,3 +9,4 @@ CONFIG_S390_FLIC=y
 CONFIG_S390_FLIC_KVM=$(CONFIG_KVM)
 CONFIG_VFIO_CCW=$(CONFIG_LINUX)
 CONFIG_WDT_DIAG288=y
+CONFIG_VFIO_AP=$(CONFIG_LINUX)
diff --git a/hw/vfio/Makefile.objs b/hw/vfio/Makefile.objs
index a2e7a0a..8b3f664 100644
--- a/hw/vfio/Makefile.objs
+++ b/hw/vfio/Makefile.objs
@@ -6,4 +6,5 @@ obj-$(CONFIG_SOFTMMU) += platform.o
 obj-$(CONFIG_VFIO_XGMAC) += calxeda-xgmac.o
 obj-$(CONFIG_VFIO_AMD_XGBE) += amd-xgbe.o
 obj-$(CONFIG_SOFTMMU) += spapr.o
+obj-$(CONFIG_VFIO_AP) += ap.o
 endif
diff --git a/hw/vfio/ap.c b/hw/vfio/ap.c
new file mode 100644
index 0000000..54a51aa
--- /dev/null
+++ b/hw/vfio/ap.c
@@ -0,0 +1,182 @@
+/*
+ * VFIO based AP matrix device assignment
+ *
+ * Copyright 2018 IBM Corp.
+ * Author(s): Tony Krowiak <akrowiak@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+
+#include <linux/vfio.h>
+#include <sys/ioctl.h>
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "hw/sysbus.h"
+#include "hw/vfio/vfio.h"
+#include "hw/vfio/vfio-common.h"
+#include "hw/s390x/ap-device.h"
+#include "qemu/error-report.h"
+#include "qemu/queue.h"
+#include "qemu/option.h"
+#include "qemu/config-file.h"
+#include "cpu.h"
+#include "kvm_s390x.h"
+#include "sysemu/sysemu.h"
+
+#define VFIO_AP_DEVICE_TYPE      "vfio-ap"
+
+typedef struct VFIOAPDevice {
+    APDevice apdev;
+    VFIODevice vdev;
+    QTAILQ_ENTRY(VFIOAPDevice) sibling;
+} VFIOAPDevice;
+
+VFIOAPDevice *vfio_apdev;
+
+static void vfio_ap_compute_needs_reset(VFIODevice *vdev)
+{
+    vdev->needs_reset = false;
+}
+
+/*
+ * We don't need vfio_hot_reset_multi and vfio_eoi operations for
+ * vfio-ap-matrix device now.
+ */
+struct VFIODeviceOps vfio_ap_ops = {
+    .vfio_compute_needs_reset = vfio_ap_compute_needs_reset,
+};
+
+static void vfio_ap_put_device(VFIOAPDevice *vapdev)
+{
+    g_free(vapdev->vdev.name);
+    vfio_put_base_device(&vapdev->vdev);
+}
+
+static VFIOGroup *vfio_ap_get_group(VFIOAPDevice *vapdev, Error **errp)
+{
+    char *tmp, group_path[PATH_MAX];
+    ssize_t len;
+    int groupid;
+
+    tmp = g_strdup_printf("%s/iommu_group", vapdev->vdev.sysfsdev);
+    len = readlink(tmp, group_path, sizeof(group_path));
+    g_free(tmp);
+
+    if (len <= 0 || len >= sizeof(group_path)) {
+        error_setg(errp, "%s: no iommu_group found for %s",
+                   VFIO_AP_DEVICE_TYPE, vapdev->vdev.sysfsdev);
+        return NULL;
+    }
+
+    group_path[len] = 0;
+
+    if (sscanf(basename(group_path), "%d", &groupid) != 1) {
+        error_setg(errp, "vfio: failed to read %s", group_path);
+        return NULL;
+    }
+
+    return vfio_get_group(groupid, &address_space_memory, errp);
+}
+
+static void vfio_ap_realize(DeviceState *dev, Error **errp)
+{
+    VFIOGroup *vfio_group;
+    APDevice *apdev = DO_UPCAST(APDevice, parent_obj, dev);
+    char *mdevid;
+    Error *local_err = NULL;
+    int ret;
+
+    /*
+     * Since a guest's matrix is configured in its entirety by the mediated
+     * matrix device and hot plug is not currently supported, there is no
+     * need to have more than one vfio-ap device. Check if a vfio-ap device
+     * has already been defined.
+     */
+    if (vfio_apdev) {
+        error_setg(&local_err, "Only one %s device is allowed",
+                   VFIO_AP_DEVICE_TYPE);
+        goto out_err;
+    }
+
+    if (!s390_has_feat(S390_FEAT_AP)) {
+        error_setg(&local_err, "AP support not enabled");
+        goto out_err;
+    }
+
+    vfio_apdev = DO_UPCAST(VFIOAPDevice, apdev, apdev);
+
+    vfio_group = vfio_ap_get_group(vfio_apdev, &local_err);
+    if (!vfio_group) {
+        goto out_err;
+    }
+
+    vfio_apdev->vdev.ops = &vfio_ap_ops;
+    vfio_apdev->vdev.type = VFIO_DEVICE_TYPE_AP;
+    mdevid = basename(vfio_apdev->vdev.sysfsdev);
+    vfio_apdev->vdev.name = g_strdup_printf("%s", mdevid);
+    vfio_apdev->vdev.dev = dev;
+
+    ret = vfio_get_device(vfio_group, mdevid, &vfio_apdev->vdev, &local_err);
+    if (ret) {
+        goto out_get_dev_err;
+    }
+
+    return;
+
+out_get_dev_err:
+    vfio_ap_put_device(vfio_apdev);
+    vfio_put_group(vfio_group);
+out_err:
+    vfio_apdev = NULL;
+    error_propagate(errp, local_err);
+}
+
+static void vfio_ap_unrealize(DeviceState *dev, Error **errp)
+{
+    APDevice *apdev = DO_UPCAST(APDevice, parent_obj, dev);
+    VFIOAPDevice *vapdev = DO_UPCAST(VFIOAPDevice, apdev, apdev);
+    VFIOGroup *group = vapdev->vdev.group;
+
+    vfio_ap_put_device(vapdev);
+    vfio_put_group(group);
+    vfio_apdev = NULL;
+}
+
+static Property vfio_ap_properties[] = {
+    DEFINE_PROP_STRING("sysfsdev", VFIOAPDevice, vdev.sysfsdev),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static const VMStateDescription vfio_ap_vmstate = {
+    .name = VFIO_AP_DEVICE_TYPE,
+    .unmigratable = 1,
+};
+
+static void vfio_ap_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->props = vfio_ap_properties;
+    dc->vmsd = &vfio_ap_vmstate;
+    dc->desc = "VFIO-based AP device assignment";
+    dc->realize = vfio_ap_realize;
+    dc->unrealize = vfio_ap_unrealize;
+    dc->hotpluggable = false;
+}
+
+static const TypeInfo vfio_ap_info = {
+    .name = VFIO_AP_DEVICE_TYPE,
+    .parent = AP_DEVICE_TYPE,
+    .instance_size = sizeof(VFIOAPDevice),
+    .class_init = vfio_ap_class_init,
+};
+
+static void vfio_ap_type_init(void)
+{
+    type_register_static(&vfio_ap_info);
+    vfio_apdev = NULL;
+}
+
+type_init(vfio_ap_type_init)
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index d936014..f29df6e 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -47,6 +47,7 @@ enum {
     VFIO_DEVICE_TYPE_PCI = 0,
     VFIO_DEVICE_TYPE_PLATFORM = 1,
     VFIO_DEVICE_TYPE_CCW = 2,
+    VFIO_DEVICE_TYPE_AP = 3,
 };
 
 typedef struct VFIOMmap {
-- 
1.7.1