Re: [Qemu-devel] [PATCH v7 07/13] vfio/ccw: vfio based subchannel passthrough driver

[Alex Williamson <alex.williamson@redhat.com>]

On Fri,  5 May 2017 04:03:46 +0200
Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com> wrote:

> 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,sysfsdev=$mdev_file_path,devno=xx.x.xxxx'
> 
> Signed-off-by: Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
> Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
> ---


Acked-by: Alex Williamson <alex.williamson@redhat.com>


>  default-configs/s390x-softmmu.mak |   1 +
>  hw/vfio/Makefile.objs             |   1 +
>  hw/vfio/ccw.c                     | 187 ++++++++++++++++++++++++++++++++++++++
>  include/hw/vfio/vfio-common.h     |   1 +
>  4 files changed, 190 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/vfio/Makefile.objs b/hw/vfio/Makefile.objs
> index 05e7fbb..c3ab909 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_VFIO_XGMAC) += calxeda-xgmac.o
>  obj-$(CONFIG_VFIO_AMD_XGBE) += amd-xgbe.o
> diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> new file mode 100644
> index 0000000..7d2497c
> --- /dev/null
> +++ b/hw/vfio/ccw.c
> @@ -0,0 +1,187 @@
> +/*
> + * 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 operations 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, Error **errp)
> +{
> +    char *tmp, group_path[PATH_MAX];
> +    ssize_t len;
> +    int groupid;
> +
> +    tmp = g_strdup_printf("/sys/bus/css/devices/%x.%x.%04x/%s/iommu_group",
> +                          cdev->hostid.cssid, cdev->hostid.ssid,
> +                          cdev->hostid.devid, cdev->mdevid);
> +    len = readlink(tmp, group_path, sizeof(group_path));
> +    g_free(tmp);
> +
> +    if (len <= 0 || len >= sizeof(group_path)) {
> +        error_setg(errp, "vfio: no iommu_group found");
> +        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_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);
> +    Error *err = NULL;
> +
> +    /* Call the class init function for subchannel. */
> +    if (cdc->realize) {
> +        cdc->realize(cdev, vcdev->vdev.sysfsdev, &err);
> +        if (err) {
> +            goto out_err_propagate;
> +        }
> +    }
> +
> +    group = vfio_ccw_get_group(cdev, &err);
> +    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(&err, "vfio: subchannel %s has already been attached",
> +                       vcdev->vdev.name);
> +            goto out_device_err;
> +        }
> +    }
> +
> +    if (vfio_get_device(group, cdev->mdevid, &vcdev->vdev, &err)) {
> +        goto out_device_err;
> +    }
> +
> +    return;
> +
> +out_device_err:
> +    vfio_put_group(group);
> +out_group_err:
> +    if (cdc->unrealize) {
> +        cdc->unrealize(cdev, NULL);
> +    }
> +out_err_propagate:
> +    error_propagate(errp, err);
> +}
> +
> +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;
> +
> +    vfio_put_device(vcdev);
> +    vfio_put_group(group);
> +
> +    if (cdc->unrealize) {
> +        cdc->unrealize(cdev, errp);
> +    }
> +}
> +
> +static Property vfio_ccw_properties[] = {
> +    DEFINE_PROP_STRING("sysfsdev", VFIOCCWDevice, vdev.sysfsdev),
> +    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 {