Re: [PATCH 2/3] vhost-scsi: new device supporting the tcm_vhost Linux kernel module

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Mar 27, 2013 at 03:45:42PM -0700, Nicholas A. Bellinger wrote:
> On Thu, 2013-03-28 at 00:28 +0200, Michael S. Tsirkin wrote:
> > On Wed, Mar 27, 2013 at 09:59:45PM +0000, Nicholas A. Bellinger wrote:
> > > From: Paolo Bonzini <pbonzini@redhat.com>
> > > 
> > > The WWPN specified in configfs is passed to "-device vhost-scsi-pci".
> > > The tgpt field of the SET_ENDPOINT ioctl is obsolete now, so it is not
> > > available from the QEMU command-line.  Instead, I hardcode it to zero.
> > > 
> > > Changes in V4:
> > >    - Set event_idx=off by default (nab, thanks asias)
> > 
> > Why? What's going on here?
> > 
> 
> Not disabling event_idx by default, or disabling from the command line
> ends up resulting in ->handle_kick() not getting called for subsequent
> commands..
> 
> I spent some time trying to track this down recently with no luck, and
> AFAICT it's always been required in order for vhost-scsi to function.

Hmm this is a bug in kernel then. A better work-around is
to disable EVENT_IDX in kernel. Let's do it for 3.9?
Then when we fix it, things just work for userspace.

> > >    - Disable hotplug feature bit for v3.9 tcm_vhost kernel code, need to
> > >      re-enable in v3.10 (nab)
> > 
> > Userspace needs to support detecting host features
> > at runtime, based on dev->features.
> > In particular this applies to event_idx, but also hotplug.
> > See vhost_net_get_features.
> 
> <nod>, will get this fixed up.
> 
> > 
> > >    - Update to latest qemu.git/master HEAD
> > > 
> > > Changes in V3:
> > >    - Drop ioeventfd vhost_scsi_properties (asias, thanks stefanha)
> > >    - Add CONFIG_VHOST_SCSI (asias, thanks stefanha)
> > >    - Add hotplug feature bit
> > > 
> > > Changes in V2:
> > >    - Add backend guest masking support (nab)
> > >    - Bump ABI_VERSION to 1 (nab)
> > >    - Set up set_guest_notifiers (asias)
> > >    - Set up vs->dev.vq_index (asias)
> > >    - Drop vs->vs.vdev.{set,clear}_vhost_endpoint (asias)
> > >    - Drop VIRTIO_CONFIG_S_DRIVER check in vhost_scsi_set_status (asias)
> > > 
> > > Howto:
> > >    Use the latest seabios, at least commit b44a7be17b
> > >    git clone git://git.seabios.org/seabios.git
> > >    make
> > >    cp out/bios.bin /usr/share/qemu/bios.bin
> > >    qemu -device vhost-scsi-pci,wwpn=naa.6001405bd4e8476d,event_idx=off
> > > ...
> > > 
> > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> > > Signed-off-by: Asias He <asias@redhat.com>
> > > Cc: Michael S. Tsirkin <mst@redhat.com>
> > > Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
> > > ---
> > >  configure                  |   15 +++-
> > >  hw/Makefile.objs           |    5 +-
> > >  hw/s390x/s390-virtio-bus.c |   35 +++++++
> > >  hw/vhost-scsi.c            |  241 ++++++++++++++++++++++++++++++++++++++++++++
> > >  hw/vhost-scsi.h            |   66 ++++++++++++
> > >  hw/virtio-pci.c            |   62 +++++++++++
> > >  hw/virtio-scsi.h           |    2 +
> > >  7 files changed, 424 insertions(+), 2 deletions(-)
> > >  create mode 100644 hw/vhost-scsi.c
> > >  create mode 100644 hw/vhost-scsi.h
> > > 
> 
> <SNIP>
> 
> > > diff --git a/hw/vhost-scsi.h b/hw/vhost-scsi.h
> > > new file mode 100644
> > > index 0000000..b01f012
> > > --- /dev/null
> > > +++ b/hw/vhost-scsi.h
> > > @@ -0,0 +1,66 @@
> > > +/*
> > > + * vhost_scsi host device
> > > + *
> > > + * Copyright IBM, Corp. 2011
> > > + *
> > > + * Authors:
> > > + *  Stefan Hajnoczi   <stefanha@linux.vnet.ibm.com>
> > > + *
> > > + * This work is licensed under the terms of the GNU LGPL, version 2 or later.
> > > + * See the COPYING.LIB file in the top-level directory.
> > > + *
> > > + */
> > > +
> > > +#ifndef VHOST_SCSI_H
> > > +#define VHOST_SCSI_H
> > > +
> > > +#include "qemu-common.h"
> > > +#include "qdev.h"
> > > +#include "virtio-scsi.h"
> > > +
> > > +/*
> > > + * Used by QEMU userspace to ensure a consistent vhost-scsi ABI.
> > > + *
> > > + * ABI Rev 0: July 2012 version starting point for v3.6-rc merge candidate +
> > > + *            RFC-v2 vhost-scsi userspace.  Add GET_ABI_VERSION ioctl usage
> > > + * ABI Rev 1: January 2013. Ignore vhost_tpgt filed in struct vhost_scsi_target.
> > > + * 	      All the targets under vhost_wwpn can be seen and used by guest.
> > > + */
> > > +
> > > +#define VHOST_SCSI_ABI_VERSION 1
> > > +
> > > +/* TODO #include <linux/vhost.h> properly */
> > > +/* For VHOST_SCSI_SET_ENDPOINT/VHOST_SCSI_CLEAR_ENDPOINT ioctl */
> > > +struct vhost_scsi_target {
> > > +    int abi_version;
> > > +    char vhost_wwpn[224];
> > > +    unsigned short vhost_tpgt;
> > > +    unsigned short reserved;
> > > +};
> > > +
> > > +enum vhost_scsi_vq_list {
> > > +    VHOST_SCSI_VQ_CONTROL = 0,
> > > +    VHOST_SCSI_VQ_EVENT = 1,
> > > +    VHOST_SCSI_VQ_NUM_FIXED = 2,
> > > +};
> > > +
> > > +#define VHOST_VIRTIO 0xAF
> > > +#define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct vhost_scsi_target)
> > > +#define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct vhost_scsi_target)
> > > +#define VHOST_SCSI_GET_ABI_VERSION _IOW(VHOST_VIRTIO, 0x42, int)
> > > +
> > > +#define DEFINE_VHOST_SCSI_PROPERTIES(_state, _features_field, _conf_field) \
> > > +    DEFINE_PROP_BIT("indirect_desc", _state, _features_field, VIRTIO_RING_F_INDIRECT_DESC, true), \
> > > +    DEFINE_PROP_BIT("event_idx", _state, _features_field, VIRTIO_RING_F_EVENT_IDX, false), \
> > 
> > Maybe this works around some bug?
> > Needs a comment with motivation.
> > 
> > Ideally we won't do this, use DEFINE_VIRTIO_COMMON_FEATURES
> > so that adding properties to all devices will be easier
> > in the future.
> 
> AFAICT vhost-scsi has never worked without event_idx=off, so disabling
> it by default here made sense.  ;)
> 
> > 
> > > +    DEFINE_PROP_STRING("vhostfd", _state, _conf_field.vhostfd), \
> > > +    DEFINE_PROP_STRING("wwpn", _state, _conf_field.wwpn), \
> > > +    DEFINE_PROP_UINT32("num_queues", _state, _conf_field.num_queues, 1), \
> > > +    DEFINE_PROP_UINT32("max_sectors", _state, _conf_field.max_sectors, 0xFFFF), \
> > > +    DEFINE_PROP_UINT32("cmd_per_lun", _state, _conf_field.cmd_per_lun, 128), \
> > > +    DEFINE_PROP_BIT("hotplug", _state, _features_field, VIRTIO_SCSI_F_HOTPLUG, true)
> > 
> > Seems unused?
> 
> Looks like left-over debug code from Asias..
> 
> Dropping this now..
> 
> > 
> > > +
> > > +VirtIODevice *vhost_scsi_init(DeviceState *dev, VirtIOSCSIConf *proxyconf);
> > > +void vhost_scsi_exit(VirtIODevice *vdev);
> > > +
> > > +
> > > +#endif
> > > diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
> > > index f3ece78..0d67b84 100644
> > > --- a/hw/virtio-pci.c
> > > +++ b/hw/virtio-pci.c
> > > @@ -22,6 +22,7 @@
> > >  #include "hw/virtio-net.h"
> > >  #include "hw/virtio-serial.h"
> > >  #include "hw/virtio-scsi.h"
> > > +#include "hw/vhost-scsi.h"
> > >  #include "hw/pci/pci.h"
> > >  #include "qemu/error-report.h"
> > >  #include "hw/pci/msi.h"
> > > @@ -1247,6 +1248,64 @@ static const TypeInfo virtio_scsi_info = {
> > >      .class_init    = virtio_scsi_class_init,
> > >  };
> > >  
> > > +#ifdef CONFIG_VHOST_SCSI
> > > +static int vhost_scsi_init_pci(PCIDevice *pci_dev)
> > > +{
> > > +    VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
> > > +    VirtIODevice *vdev;
> > > +
> > > +    vdev = vhost_scsi_init(&pci_dev->qdev, &proxy->scsi);
> > > +    if (!vdev) {
> > > +        return -EINVAL;
> > > +    }
> > > +
> > > +    vdev->nvectors = proxy->nvectors == DEV_NVECTORS_UNSPECIFIED
> > > +                                        ? proxy->scsi.num_queues + 3
> > > +                                        : proxy->nvectors;
> > > +    virtio_init_pci(proxy, vdev);
> > > +
> > > +    /* make the actual value visible */
> > > +    proxy->nvectors = vdev->nvectors;
> > > +    return 0;
> > > +}
> > > +
> > > +static void vhost_scsi_exit_pci(PCIDevice *pci_dev)
> > > +{
> > > +    VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
> > > +
> > > +    vhost_scsi_exit(proxy->vdev);
> > > +    virtio_exit_pci(pci_dev);
> > > +}
> > > +
> > > +static Property vhost_scsi_properties[] = {
> > > +    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, DEV_NVECTORS_UNSPECIFIED),
> > > +    DEFINE_VHOST_SCSI_PROPERTIES(VirtIOPCIProxy, host_features, scsi),
> > > +    DEFINE_PROP_END_OF_LIST(),
> > > +};
> > > +
> > > +static void vhost_scsi_class_init(ObjectClass *klass, void *data)
> > > +{
> > > +    DeviceClass *dc = DEVICE_CLASS(klass);
> > > +    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
> > > +
> > > +    k->init = vhost_scsi_init_pci;
> > > +    k->exit = vhost_scsi_exit_pci;
> > > +    k->vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET;
> > > +    k->device_id = PCI_DEVICE_ID_VIRTIO_SCSI;
> > > +    k->revision = 0x00;
> > > +    k->class_id = PCI_CLASS_STORAGE_SCSI;
> > > +    dc->reset = virtio_pci_reset;
> > > +    dc->props = vhost_scsi_properties;
> > > +}
> > > +
> > > +static const TypeInfo vhost_scsi_info = {
> > > +    .name          = "vhost-scsi-pci",
> > > +    .parent        = TYPE_PCI_DEVICE,
> > > +    .instance_size = sizeof(VirtIOPCIProxy),
> > > +    .class_init    = vhost_scsi_class_init,
> > > +};
> > > +#endif
> > > +
> > >  #ifdef CONFIG_VIRTFS
> > >  static int virtio_9p_init_pci(PCIDevice *pci_dev)
> > >  {
> > > @@ -1495,6 +1554,9 @@ static void virtio_pci_register_types(void)
> > >      type_register_static(&virtio_serial_info);
> > >      type_register_static(&virtio_balloon_info);
> > >      type_register_static(&virtio_scsi_info);
> > > +#ifdef CONFIG_VHOST_SCSI
> > > +    type_register_static(&vhost_scsi_info);
> > > +#endif
> > >      type_register_static(&virtio_rng_info);
> > >      type_register_static(&virtio_pci_bus_info);
> > >      type_register_static(&virtio_pci_info);
> > > diff --git a/hw/virtio-scsi.h b/hw/virtio-scsi.h
> > > index 2bcf606..356bf38 100644
> > > --- a/hw/virtio-scsi.h
> > > +++ b/hw/virtio-scsi.h
> > > @@ -142,6 +142,8 @@ struct VirtIOSCSIConf {
> > >      uint32_t num_queues;
> > >      uint32_t max_sectors;
> > >      uint32_t cmd_per_lun;
> > > +    char *vhostfd;
> > > +    char *wwpn;
> > >  };
> > >  
> > >  typedef struct VirtIOSCSICommon {
> > > -- 
> > > 1.7.2.5
> > --
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