Re: [RFCv2 5/7] vhost/scsi: Enable T10 PI IOV -> SGL memory mapping

["Nicholas A. Bellinger" <nab@linux-iscsi.org>]

On Mon, 2014-03-17 at 12:02 +0100, Paolo Bonzini wrote:
> Il 17/03/2014 06:32, Nicholas A. Bellinger ha scritto:
> > +		if (vq->iov[0].iov_len == sizeof(v_req_pi)) {
> > +			req = (unsigned char *)&v_req_pi;
> > +			target = &v_req_pi.lun[1];
> > +			req_size = sizeof(v_req_pi);
> > +			hdr_pi = true;
> > +		} else if (vq->iov[0].iov_len == sizeof(v_req)) {
> > +			req = (unsigned char *)&v_req;
> > +			target = &v_req.lun[1];
> > +			req_size = sizeof(v_req);
> > +			hdr_pi = false;
> 
> The right check here is on the negotiated features.
> 

Mmmm, so this had been making the assumption that the PI enabled header
would only be used when the CDB itself had an associated PI SGL.

I agree it's cleaner to always use the PI enabled header when the
feature bit has been negotiated.  Fixing this up for -v3.

> You need a matching QEMU patch to enable the protection information
> feature, like this (untested):
> 

<nod>

Thanks Paolo!

--nab

> diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
> index 3983a5b..4c8d5cd 100644
> --- a/hw/scsi/vhost-scsi.c
> +++ b/hw/scsi/vhost-scsi.c
> @@ -154,6 +154,9 @@ static uint32_t vhost_scsi_get_features(VirtIODevice *vdev,
>      if (!(s->dev.features & (1 << VIRTIO_SCSI_F_HOTPLUG))) {
>          features &= ~(1 << VIRTIO_SCSI_F_HOTPLUG);
>      }
> +    if (!(s->dev.features & (1 << VIRTIO_SCSI_F_T10_PI))) {
> +        features &= ~(1 << VIRTIO_SCSI_F_T10_PI);
> +    }
>  
>      return features;
>  }
> diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
> index 6610b3a..4a551e9 100644
> --- a/hw/scsi/virtio-scsi.c
> +++ b/hw/scsi/virtio-scsi.c
> @@ -629,6 +629,9 @@ static void virtio_scsi_device_realize(DeviceState *dev, Error **errp)
>          return;
>      }
>  
> +    /* Protection information is not supported yet.  */
> +    dev->guest_features &= ~VIRTIO_SCSI_F_T10_PI;
> +
>      scsi_bus_new(&s->bus, sizeof(s->bus), dev,
>                   &virtio_scsi_scsi_info, vdev->bus_name);
>  
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 9010246..8621fbf 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -267,6 +267,16 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t);
>              .value    = "no",\
>          },\
>          {\
> +            .driver   = "virtio-scsi-pci",\
> +            .property = "prot_info",\
> +            .value    = "off",\
> +        },\
> +        {\
> +            .driver   = "vhost-scsi-pci",\
> +            .property = "prot_info",\
> +            .value    = "off",\
> +        },\
> +        {\
>              .driver   = "PIIX4_PM",\
>              .property = "acpi-pci-hotplug-with-bridge-support",\
>              .value    = "off",\
> diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
> index 42b1024..a555f49 100644
> --- a/include/hw/virtio/virtio-scsi.h
> +++ b/include/hw/virtio/virtio-scsi.h
> @@ -34,6 +34,7 @@
>  #define VIRTIO_SCSI_F_INOUT                    0
>  #define VIRTIO_SCSI_F_HOTPLUG                  1
>  #define VIRTIO_SCSI_F_CHANGE                   2
> +#define VIRTIO_SCSI_F_T10_PI                   3
>  
>  #define VIRTIO_SCSI_VQ_SIZE     128
>  #define VIRTIO_SCSI_CDB_SIZE    32
> @@ -184,7 +185,9 @@ typedef struct {
>      DEFINE_PROP_BIT("hotplug", _state, _feature_field, VIRTIO_SCSI_F_HOTPLUG,  \
>                                                         true),                  \
>      DEFINE_PROP_BIT("param_change", _state, _feature_field,                    \
> -                                            VIRTIO_SCSI_F_CHANGE, true)
> +                                            VIRTIO_SCSI_F_CHANGE, true)        \
> +    DEFINE_PROP_BIT("prot_info", _state, _feature_field,                       \
> +                                            VIRTIO_SCSI_F_T10_PI, true)
>  
>  void virtio_scsi_common_realize(DeviceState *dev, Error **errp);
>  void virtio_scsi_common_unrealize(DeviceState *dev, Error **errp);
>