Re: [Qemu-devel] [PATCH RFC v5 10/19] s390x/virtio-ccw: add virtio set-revision call

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

On Tue, Dec 02, 2014 at 02:00:18PM +0100, Cornelia Huck wrote:
> From: Thomas Huth <thuth@linux.vnet.ibm.com>
> 
> Handle the virtio-ccw revision according to what the guest sets.
> When revision 1 is selected, we have a virtio-1 standard device
> with byteswapping for the virtio rings.
> 
> When a channel gets disabled, we have to revert to the legacy behavior
> in case the next user of the device does not negotiate the revision 1
> anymore (e.g. the boot firmware uses revision 1, but the operating
> system only uses the legacy mode).
> 
> Note that revisions > 0 are still disabled.
> 
> Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> ---
>  hw/s390x/virtio-ccw.c |   52 +++++++++++++++++++++++++++++++++++++++++++++++++
>  hw/s390x/virtio-ccw.h |    5 +++++
>  2 files changed, 57 insertions(+)
> 
> diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
> index e434718..5311d9f 100644
> --- a/hw/s390x/virtio-ccw.c
> +++ b/hw/s390x/virtio-ccw.c
> @@ -20,9 +20,11 @@
>  #include "hw/virtio/virtio-net.h"
>  #include "hw/sysbus.h"
>  #include "qemu/bitops.h"
> +#include "hw/virtio/virtio-access.h"
>  #include "hw/virtio/virtio-bus.h"
>  #include "hw/s390x/adapter.h"
>  #include "hw/s390x/s390_flic.h"
> +#include "linux/virtio_config.h"
>  
>  #include "ioinst.h"
>  #include "css.h"
> @@ -260,6 +262,12 @@ typedef struct VirtioThinintInfo {
>      uint8_t isc;
>  } QEMU_PACKED VirtioThinintInfo;
>  
> +typedef struct VirtioRevInfo {
> +    uint16_t revision;
> +    uint16_t length;
> +    uint8_t data[0];
> +} QEMU_PACKED VirtioRevInfo;
> +
>  /* Specify where the virtqueues for the subchannel are in guest memory. */
>  static int virtio_ccw_set_vqs(SubchDev *sch, uint64_t addr, uint32_t align,
>                                uint16_t index, uint16_t num)
> @@ -299,6 +307,7 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
>  {
>      int ret;
>      VqInfoBlock info;
> +    VirtioRevInfo revinfo;
>      uint8_t status;
>      VirtioFeatDesc features;
>      void *config;
> @@ -375,6 +384,13 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
>                  features.features = (uint32_t)dev->host_features;
>              } else if (features.index == 1) {
>                  features.features = (uint32_t)(dev->host_features >> 32);
> +                /*
> +                 * Don't offer version 1 to the guest if it did not
> +                 * negotiate at least revision 1.
> +                 */
> +                if (dev->revision <= 0) {
> +                    features.features &= ~(1 << (VIRTIO_F_VERSION_1 - 32));
> +                }
>              } else {
>                  /* Return zeroes if the guest supports more feature bits. */
>                  features.features = 0;
> @@ -406,6 +422,13 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
>                                      (vdev->guest_features & 0xffffffff00000000) |
>                                      features.features);
>              } else if (features.index == 1) {
> +                /*
> +                 * The guest should not set version 1 if it didn't
> +                 * negotiate a revision >= 1.
> +                 */
> +                if (dev->revision <= 0) {
> +                    features.features &= ~(1 << (VIRTIO_F_VERSION_1 - 32));
> +                }
>                  virtio_set_features(vdev,
>                                      (vdev->guest_features & 0x00000000ffffffff) |
>                                      ((uint64_t)features.features << 32));
> @@ -608,6 +631,25 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
>              }
>          }
>          break;
> +    case CCW_CMD_SET_VIRTIO_REV:
> +        len = sizeof(revinfo);
> +        if (ccw.count < len || (check_len && ccw.count > len)) {
> +            ret = -EINVAL;
> +            break;
> +        }
> +        if (!ccw.cda) {
> +            ret = -EFAULT;
> +            break;
> +        }
> +        cpu_physical_memory_read(ccw.cda, &revinfo, len);
> +        if (dev->revision >= 0 ||
> +            revinfo.revision > VIRTIO_CCW_REV_MAX) {
> +            ret = -ENOSYS;
> +            break;
> +        }
> +        ret = 0;
> +        dev->revision = revinfo.revision;
> +        break;
>      default:
>          ret = -ENOSYS;
>          break;
> @@ -615,6 +657,13 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
>      return ret;
>  }
>  
> +static void virtio_sch_disable_cb(SubchDev *sch)
> +{
> +    VirtioCcwDevice *dev = sch->driver_data;
> +
> +    dev->revision = -1;
> +}
> +
>  static int virtio_ccw_device_init(VirtioCcwDevice *dev, VirtIODevice *vdev)
>  {
>      unsigned int cssid = 0;
> @@ -740,6 +789,7 @@ static int virtio_ccw_device_init(VirtioCcwDevice *dev, VirtIODevice *vdev)
>      css_sch_build_virtual_schib(sch, 0, VIRTIO_CCW_CHPID_TYPE);
>  
>      sch->ccw_cb = virtio_ccw_cb;
> +    sch->disable_cb = virtio_sch_disable_cb;
>  
>      /* Build senseid data. */
>      memset(&sch->id, 0, sizeof(SenseId));
> @@ -747,6 +797,8 @@ static int virtio_ccw_device_init(VirtioCcwDevice *dev, VirtIODevice *vdev)
>      sch->id.cu_type = VIRTIO_CCW_CU_TYPE;
>      sch->id.cu_model = vdev->device_id;
>  
> +    dev->revision = -1;
> +
>      /* Set default feature bits that are offered by the host. */
>      dev->host_features = 0;
>      virtio_add_feature(&dev->host_features, VIRTIO_F_NOTIFY_ON_EMPTY);

You should also clear it on device reset.


> diff --git a/hw/s390x/virtio-ccw.h b/hw/s390x/virtio-ccw.h
> index 9087f7a..fe5c782 100644
> --- a/hw/s390x/virtio-ccw.h
> +++ b/hw/s390x/virtio-ccw.h
> @@ -40,6 +40,7 @@
>  #define CCW_CMD_SET_CONF_IND 0x53
>  #define CCW_CMD_READ_VQ_CONF 0x32
>  #define CCW_CMD_SET_IND_ADAPTER 0x73
> +#define CCW_CMD_SET_VIRTIO_REV 0x83
>  
>  #define TYPE_VIRTIO_CCW_DEVICE "virtio-ccw-device"
>  #define VIRTIO_CCW_DEVICE(obj) \
> @@ -68,6 +69,9 @@ typedef struct VirtIOCCWDeviceClass {
>      int (*exit)(VirtioCcwDevice *dev);
>  } VirtIOCCWDeviceClass;
>  
> +/* The maximum virtio revision we support. */
> +#define VIRTIO_CCW_REV_MAX 0
> +
>  /* Performance improves when virtqueue kick processing is decoupled from the
>   * vcpu thread using ioeventfd for some devices. */
>  #define VIRTIO_CCW_FLAG_USE_IOEVENTFD_BIT 1
> @@ -86,6 +90,7 @@ struct VirtioCcwDevice {
>      SubchDev *sch;
>      char *bus_id;
>      uint64_t host_features;
> +    int revision;
>      VirtioBusState bus;
>      bool ioeventfd_started;
>      bool ioeventfd_disabled;
> -- 
> 1.7.9.5