[PATCH RFC v2 07/12] vfio/ccw: vfio based subchannel passthrough driver

Dong Jia Shi
2017-01-12T07:25:08Z

From: Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>

We use the IOMMU_TYPE1 of VFIO to realize the subchannels
passthrough, implement a vfio based subchannels passthrough
driver called "vfio-ccw".

Support qemu parameters in the style of:
"-device vfio-ccw,id=xx,hostid=xx(,guestid=xx),mdevid=xx"

Signed-off-by: Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
---
default-configs/s390x-softmmu.mak | 1 +
hw/s390x/s390-ccw.h | 1 +
hw/vfio/Makefile.objs | 1 +
hw/vfio/ccw.c | 209 ++++++++++++++++++++++++++++++++++++++
include/hw/vfio/vfio-common.h | 1 +
5 files changed, 213 insertions(+)
create mode 100644 hw/vfio/ccw.c

diff --git a/default-configs/s390x-softmmu.mak b/default-configs/s390x-softmmu.mak
index 36e15de..5576b0a 100644
--- a/default-configs/s390x-softmmu.mak
+++ b/default-configs/s390x-softmmu.mak
@@ -4,4 +4,5 @@ CONFIG_VIRTIO=y
CONFIG_SCLPCONSOLE=y
CONFIG_S390_FLIC=y
CONFIG_S390_FLIC_KVM=$(CONFIG_KVM)
+CONFIG_VFIO_CCW=$(CONFIG_LINUX)
CONFIG_WDT_DIAG288=y
diff --git a/hw/s390x/s390-ccw.h b/hw/s390x/s390-ccw.h
index 9ced8cb..1fa4a97 100644
--- a/hw/s390x/s390-ccw.h
+++ b/hw/s390x/s390-ccw.h
@@ -26,6 +26,7 @@
typedef struct S390CCWDevice {
CcwDevice parent_obj;
CssDevId hostid;
+ char *mdevid;
} S390CCWDevice;

typedef struct S390CCWDeviceClass {
diff --git a/hw/vfio/Makefile.objs b/hw/vfio/Makefile.objs
index c25e32b..4c3a462 100644
--- a/hw/vfio/Makefile.objs
+++ b/hw/vfio/Makefile.objs
@@ -1,6 +1,7 @@
ifeq ($(CONFIG_LINUX), y)
obj-$(CONFIG_SOFTMMU) += common.o
obj-$(CONFIG_PCI) += pci.o pci-quirks.o
+obj-$(CONFIG_VFIO_CCW) += ccw.o
obj-$(CONFIG_SOFTMMU) += platform.o
obj-$(CONFIG_SOFTMMU) += calxeda-xgmac.o
obj-$(CONFIG_SOFTMMU) += amd-xgbe.o
diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
new file mode 100644
index 0000000..881010b
--- /dev/null
+++ b/hw/vfio/ccw.c
@@ -0,0 +1,209 @@
+/*
+ * vfio based subchannel assignment support
+ *
+ * Copyright 2017 IBM Corp.
+ * Author(s): Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
+ * Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
+ * Pierre Morel <pmorel@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or(at
+ * your option) any 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/s390-ccw.h"
+#include "hw/s390x/ccw-device.h"
+
+#define TYPE_VFIO_CCW "vfio-ccw"
+typedef struct VFIOCCWDevice {
+ S390CCWDevice cdev;
+ VFIODevice vdev;
+} VFIOCCWDevice;
+
+static void vfio_ccw_compute_needs_reset(VFIODevice *vdev)
+{
+ vdev->needs_reset = false;
+}
+
+/*
+ * We don't need vfio_hot_reset_multi and vfio_eoi operationis for
+ * vfio_ccw device now.
+ */
+struct VFIODeviceOps vfio_ccw_ops = {
+ .vfio_compute_needs_reset = vfio_ccw_compute_needs_reset,
+};
+
+static void vfio_ccw_reset(DeviceState *dev)
+{
+ CcwDevice *ccw_dev = DO_UPCAST(CcwDevice, parent_obj, dev);
+ S390CCWDevice *cdev = DO_UPCAST(S390CCWDevice, parent_obj, ccw_dev);
+ VFIOCCWDevice *vcdev = DO_UPCAST(VFIOCCWDevice, cdev, cdev);
+
+ ioctl(vcdev->vdev.fd, VFIO_DEVICE_RESET);
+}
+
+static void vfio_put_device(VFIOCCWDevice *vcdev)
+{
+ g_free(vcdev->vdev.name);
+ vfio_put_base_device(&vcdev->vdev);
+}
+
+static VFIOGroup *vfio_ccw_get_group(S390CCWDevice *cdev, char **path,
+ Error **errp)
+{
+ struct stat st;
+ int groupid;
+ GError *gerror = NULL;
+
+ /* Check that host subchannel exists. */
+ path[0] = g_strdup_printf("/sys/bus/css/devices/%x.%x.%04x",
+ cdev->hostid.cssid,
+ cdev->hostid.ssid,
+ cdev->hostid.devid);
+ if (stat(path[0], &st) < 0) {
+ error_setg(errp, "vfio: no such host subchannel %s", path[0]);
+ return NULL;
+ }
+
+ /* Check that mediated device exists. */
+ path[1] = g_strdup_printf("%s/%s", path[0], cdev->mdevid);
+ if (stat(path[0], &st) < 0) {
+ error_setg(errp, "vfio: no such mediated device %s", path[1]);
+ return NULL;
+ }
+
+ /* Get the iommu_group patch as the interim variable. */
+ path[2] = g_strconcat(path[1], "/iommu_group", NULL);
+
+ /* Get the link file path of the device iommu_group. */
+ path[3] = g_file_read_link(path[2], &gerror);
+ if (!path[3]) {
+ error_setg(errp, "vfio: error no iommu_group for subchannel");
+ return NULL;
+ }
+
+ /* Get the device groupid. */
+ if (sscanf(basename(path[3]), "%d", &groupid) != 1) {
+ error_setg(errp, "vfio: error reading %s:%m", path[3]);
+ return NULL;
+ }
+
+ return vfio_get_group(groupid, &address_space_memory, errp);
+}
+
+static void vfio_ccw_put_group(VFIOGroup *group, char **path)
+{
+ g_free(path);
+ vfio_put_group(group);
+}
+
+static void vfio_ccw_realize(DeviceState *dev, Error **errp)
+{
+ VFIODevice *vbasedev;
+ VFIOGroup *group;
+ CcwDevice *ccw_dev = DO_UPCAST(CcwDevice, parent_obj, dev);
+ S390CCWDevice *cdev = DO_UPCAST(S390CCWDevice, parent_obj, ccw_dev);
+ VFIOCCWDevice *vcdev = DO_UPCAST(VFIOCCWDevice, cdev, cdev);
+ S390CCWDeviceClass *cdc = S390_CCW_DEVICE_GET_CLASS(cdev);
+ char *path[4] = {NULL, NULL, NULL, NULL};
+
+ /* Call the class init function for subchannel. */
+ if (cdc->realize) {
+ cdc->realize(cdev, errp);
+ if (*errp) {
+ return;
+ }
+ }
+
+ group = vfio_ccw_get_group(cdev, path, errp);
+ if (!group) {
+ goto out_group_err;
+ }
+
+ vcdev->vdev.ops = &vfio_ccw_ops;
+ vcdev->vdev.type = VFIO_DEVICE_TYPE_CCW;
+ vcdev->vdev.name = g_strdup_printf("%x.%x.%04x", cdev->hostid.cssid,
+ cdev->hostid.ssid, cdev->hostid.devid);
+ QLIST_FOREACH(vbasedev, &group->device_list, next) {
+ if (strcmp(vbasedev->name, vcdev->vdev.name) == 0) {
+ error_setg(errp, "vfio: subchannel %s has already been attached",
+ basename(path[0]));
+ goto out_device_err;
+ }
+ }
+
+ if (vfio_get_device(group, cdev->mdevid, &vcdev->vdev, errp)) {
+ goto out_device_err;
+ }
+
+ return;
+
+out_device_err:
+ vfio_ccw_put_group(group, path);
+out_group_err:
+ if (cdc->unrealize) {
+ cdc->unrealize(cdev, errp);
+ }
+}
+
+static void vfio_ccw_unrealize(DeviceState *dev, Error **errp)
+{
+ CcwDevice *ccw_dev = DO_UPCAST(CcwDevice, parent_obj, dev);
+ S390CCWDevice *cdev = DO_UPCAST(S390CCWDevice, parent_obj, ccw_dev);
+ VFIOCCWDevice *vcdev = DO_UPCAST(VFIOCCWDevice, cdev, cdev);
+ S390CCWDeviceClass *cdc = S390_CCW_DEVICE_GET_CLASS(cdev);
+ VFIOGroup *group = vcdev->vdev.group;
+
+ if (cdc->unrealize) {
+ cdc->unrealize(cdev, errp);
+ }
+
+ vfio_put_device(vcdev);
+ vfio_put_group(group);
+}
+
+static Property vfio_ccw_properties[] = {
+ DEFINE_PROP_CSS_DEV_ID("hostid", VFIOCCWDevice, cdev.hostid),
+ DEFINE_PROP_CSS_DEV_ID("guestid", VFIOCCWDevice, cdev.parent_obj.bus_id),
+ DEFINE_PROP_STRING("mdevid", VFIOCCWDevice, cdev.mdevid),
+ DEFINE_PROP_END_OF_LIST(),
+};
+
+static const VMStateDescription vfio_ccw_vmstate = {
+ .name = TYPE_VFIO_CCW,
+ .unmigratable = 1,
+};
+
+static void vfio_ccw_class_init(ObjectClass *klass, void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(klass);
+
+ dc->props = vfio_ccw_properties;
+ dc->vmsd = &vfio_ccw_vmstate;
+ dc->desc = "VFIO-based subchannel assignment";
+ dc->realize = vfio_ccw_realize;
+ dc->unrealize = vfio_ccw_unrealize;
+ dc->reset = vfio_ccw_reset;
+}
+
+static const TypeInfo vfio_ccw_info = {
+ .name = TYPE_VFIO_CCW,
+ .parent = TYPE_S390_CCW,
+ .instance_size = sizeof(VFIOCCWDevice),
+ .class_init = vfio_ccw_class_init,
+};
+
+static void register_vfio_ccw_type(void)
+{
+ type_register_static(&vfio_ccw_info);
+}
+
+type_init(register_vfio_ccw_type)
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index c582de1..9521013 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -45,6 +45,7 @@
enum {
VFIO_DEVICE_TYPE_PCI = 0,
VFIO_DEVICE_TYPE_PLATFORM = 1,
+ VFIO_DEVICE_TYPE_CCW = 2,
};

typedef struct VFIOMmap {
--
2.8.4